1

EstablishingaGreenlandIceSheetOceanObservingSystem(GriOOS)

Report from an

International Workshop

December 12-13, 2015

Fort Mason, San Francisco, CA, USA

Editors: Fiammetta Straneo (Scripps, UCSD) Twila Moon (NSIDC) Dave Sutherland (U. Oregon) Patrick Heimbach (U. Texas) Ginny Catania (U. Texas).

2

3

TableofContents

ExecutiveSummary.............................................................................................................................4

Introduction...........................................................................................................................................6

GrIOOSDesignandRequirements..................................................................................................61.WhyestablishGrIOOS?.............................................................................................................................82.Whataretheessentialvariablestobemeasured?..........................................................................83.Whatmeasurementsexistalready?.....................................................................................................8A.Atmospheric..................................................................................................................................................................8B.SeismicandGeodesy.................................................................................................................................................9C.Ocean................................................................................................................................................................................9D.RemoteSensing........................................................................................................................................................12

4.Howmanyandwhichsitesshouldwestudy?.................................................................................125.WhatistheoptimalinstrumentationandGrIOOSdesign?.........................................................14Instrumentation............................................................................................................................................................14Design.................................................................................................................................................................................15

6.Howwillmeasurementsanddatabequalitycontrolledanddistributed?...........................157.HowwillGrIOOSbefunded?.................................................................................................................15

Summary..............................................................................................................................................16

References...........................................................................................................................................17

AppendixI:ListofAttendees.........................................................................................................19

AppendixII:MeetingAgenda.........................................................................................................21

AppendixIII:Notesfromeachsession.......................................................................................24

4

GreenlandIceSheetOceanObservingSystem(GrIOOS)

ExecutiveSummaryRapid mass loss from the Greenland Ice Sheet has raised interest in glacier/ocean

interactions for two main reasons. First, increased submarine melting of marine terminatingglaciers, in part associated with changes in the ocean, has emerged as a likely trigger of theobserveddynamiciceloss.Second,increasedfreshwaterandnutrientdischargefromGreenlandisimpacting air-sea exchanges, the regional ocean circulation andmarine ecosystems.Progresshasbeenmadeoverthelastdecadeinunderstandingglacier/oceanexchangesofheatandfreshwaterin Greenland’s glacial fjords. Yet challenges remain to understand the climatic controls onsubmarinemelting, icebergcalving,andthedeliveryofmeltwaterandnutrientstothelarge-scaleocean.Theseknowledgegapstranslateintoaninabilitytoappropriatelyrepresenttheseprocessesinmodels(eveninparameterizedform)aimedatfutureprediction.Progresshasbeenhinderedbythelackofconcurrentandlong-termrecordsofglaciological,oceanic,andatmosphericparametersat the ice sheet/ocean margins – where the exchanges of heat, nutrients and freshwater areoccurring.

TheneedtoestablishaGreenlandIceSheetOceanObservingSystem,asameansofprovidinglong-term data at a number of key sites around Greenland that can inform understanding andprovide boundary conditions and validation for models, was discussed at an Internationalworkshop held in San Francisco, on December 12-13, 2015. The workshop was attended by 47participants from the USA, Canada, Greenland, Denmark, Norway, United Kingdom and Japancovering a wide range of expertise (oceanography, glaciology, climate and ice sheet modeling,marineecosystems,paleoclimatology).Specificgoalsoftheworkshopwereto:

1. Re-evaluatetheneedforGrIOOS

2. Identifytheessentialvariablestobemeasured

3. Establishwhatmeasurementsexistalready.

4. Determinehowmanyandwhichsitesshouldbecovered

5. Identifyappropriateinstrumentation

6. IdentifytherelevanttimescalesthatGrIOOSshouldaddress

7. Discussmeansofuniformlyqualitycontrollingthemeasurementsanddistributingthedata

8. Identifypotentialfundingsources

Overarchingconclusionsfromtheworkshoparesummarizedhere.ThelimitedabilityofbothoceanandicesheetmodelstocapturetheongoingchangesinGreenland,theirdriversandtheirimpactontheoceanunderlinestheneedforobtaininglong-termmeasurementsatsitesaroundGreenlandto

5

provideconstraintsonourunderstandingandabilitytomodelthesesystems.Theestablishmentofa Greenland Ice/Ocean observing system thus continues to be a key priority for understandingGreenland Ice Sheet variability. Numerous long-term projects/activities have already laid thefoundation for anobserving systemby collectingocean/atmosphere/glaciologymeasurements atspecific sites around Greenland. At present, however, these observing efforts are largelyuncoordinatedandhavefailedtoidentifyaminimum,commonsetofmeasurements,dataprotocolsanddatasharingpolicieswhichwouldbenefitthebroadercommunity.Inaddition,thecontinuationoftheseobservingeffortsistypicallyatstakesincetheyarelargelyseenasisolated,oftenprojectbasedsites.

GrIOOSshouldbuildon theseexisting sitesbydefininga commonsetof essentialmeasurementsand providing a data management model to be employed by all. Essential measurements to becollected at these sites include oceanic (temperature, salinity, pressure in the fjord and nearbyshelf), glaciological (ice velocity, thickness, meltwater runoff, mélange characteristics, terminusvariations,calvingbehavior)andatmospheric(localwindsandairtemperatureontheglacierandnearbyfjord).BathymetryandbedrockareneededinputsforanyGrIOOSsite.Paleomeasurementstoprovidetemporalcontextarestronglydesired.Aseriesof~10siteswereidentifiedbasedonanumber of criteria including existing and ongoing programs, proximity to network nodes andrelevancetothemotivationdescribedabove.

ThedevelopmentandmaintenanceofGrIOOSwillrequirecloseinternationalcollaboration.GrIOOSimplementationwillneedtobecoordinatedamongstdifferentcountries,payingcloseattentiontominimizing costs and optimizing shared logistics. It is unlikely that GrIOOS will be funded by asingle country or union. Instead, GrIOOS should identify a minimum set of measurements for aGrIOOS site and provide key data collection, quality control and processing protocols for suchmeasurements.Sharingpracticesandexperiencewillbekeytothesuccessof theprogram.Quickand centralized access to data is key, though there shouldbe flexibility so that countries arenotexcludedfromtheGrIOOSprocessforembargoreasons.

6

IntroductionMass loss fromtheGreenland icesheetquadrupled from1992-2001 to2001-2011, resulting inanetcontributiontosea-levelriseofapproximately7.5mmoverthe1992-2011period[Shepherdetal. 2012].A third to ahalf of this loss [vandenBroekeet al. 2009;Enderlinet al. 2014; vandenBroeke et al. 2016] resulted from the speed up and retreat of marine-terminating glaciers thatbegan in the late1990s [RignotandKanagaratnam2006]andcontinues to thisdate [Moonetal.2012;JoughinandSmith2013].Theglacieraccelerationandretreatisnotwellunderstoodandnotfullycapturedbymodels[e.g.,VieliandNick2011].Itisthoughttohavebeentriggeredinpartbyocean forcing [Vieli andNick 2011; Joughin et al. 2012], but the lack ofmeasurements from theoceanicmarginsofGreenlandhasmadeitchallengingtoreconstructthechainofeventsthatledtoglacierretreat[Straneoetal.2013;StraneoandHeimbach2013].

Inadditiontothe impactof theoceanontheGreenlandicesheet, increasedfreshwaterdischargefromthelandicehasthepotentialtoaffecttheoceananditsecosysteminanumberofimportantways.FresheningoftheoceanaroundGreenlandcanaffectNorthAtlanticdensewaterformation,with a potential impact on the meridional overturning circulation of the North Atlantic, itsassociatedheattransport,andhencetheregionalclimateovertheNorthAtlanticsectorandbeyond[Marsh et al. 2010; Weijer et al. 2012; Bamber et al. 2012; Lenaerts et al. 2015]. Furthermore,meltwater fromglaciersand theassociatedchemical fluxes, including theexportof labileorganiccarbon, ironandothernutrients,canimpactArcticandsub-Arcticecosystems[Arrigoetal.2017;O’Neeletal.2015].

Amulti-disciplinaryInternationalWorkshopon“UnderstandingtheResponseofGreenland’sMarine-TerminatingGlacierstoOceanicandAtmosphericForcing”washeldinBeverly,MA,inJune2013,tobringtogetherthescientificcommunityandidentifystrategiestomoveforwardonunderstandingthe Greenland ice-ocean system. One of four key recommendations that emerged from the 2013workshop, and the ensuing report which was widely circulated to include community feedback[Heimbachetal.2014],istheestablishmentofaGreenlandIce-OceanObservingSystem(GrIOOS).GrIOOS would collect long-term in situ time series of critical glaciological, oceanographic, andatmospheric variables at key locations in and around Greenland. The research communityrecognized that such measurements are needed to provide information on the time-evolvingrelationships between the different climate forcings and the glacier flow. In particular, thesemeasurements will provide an assessment of the ocean variability within the fjords, theatmospheric conditions at the terminus, and the variability of glacier dynamics. The lack of suchdata has hindered our ability to explain and model the recent glacier acceleration, creatingweaknesses in our ability to project future changes. These data are critical not only to validatehypothesesbutalsotoprovideboundaryconditions, forcings,andapointofcomparisonforbothoceanandicemodelsimulations.

GrIOOSDesignandRequirementsFollowing the recommendations made in the 2014 report, the Study of Environmental ArcticChange (SEARCH) Land Ice Action Team in collaboration with the Greenland Ice Sheet OceanInteraction (GRISO) ScienceNetwork organized aworkshop tomakeprogress on thedesign andimplementationofGrIOOS.

The workshop took place in San Francisco on December 12-13, 2015, and was attended by 47participants from the USA, Canada, Greenland, Denmark, Norway, United Kingdom and Japan(Figure 1). A steering committee selected participants on the basis of expressions of interest

7

submittedinresponsetoaworkshopannouncementwidelycirculatedonrelevant listservesandwebsites. Selections weremade to ensure the appropriate disciplinary expertise (oceanography,glaciology,climateandicesheetmodeling,marineecosystems,paleoclimatology),genderbalance,and representation from early-career scientists. Other attendees included agency programmanagers(NSF,NASA)andarepresentativeoftheGreenlandgovernment.Theworkshopwasco-located with the ISMIP-6 (Ice Sheet Model Intercomparison Project) meeting, which allowed icesheetmodelerstoattendthefirsthalf-dayandenabledcross-disciplinarydiscussionsatbreaks.

Figure1.GrIOOSWorkshopparticipants,SanFrancisco,December2015.

Presentations during short plenary sessions set the stage for detailed brainstorming amongparticipants in a mixture of breakout clusters and whole group discussions. These discussionsfocused on defining the essential measurements to be collected by GrIOOS, which glacier-fjordsystemsshouldbestudied,andmechanismsforimplementingandmaintainingthenetwork.Amongthe recommendations were support for ongoing remote sensing of glacier variability, thedeployment of a suite of relatively low-cost, yet rugged and proven, instruments to collect theessential measurements, and consideration for co-locating the network sites close to otherobservingplatformswherepossible.

Keyquestionsaddressedattheworkshopincluded:

9. WhyestablishGrIOOS?

10. Whataretheessentialvariablestobemeasured?

11. Whatmeasurementsexistalready?

12. Howmanyandwhichsitesshouldwestudy?

13. WhatistheoptimalinstrumentationandGrIOOSdesign?

14. Howwillmeasurementsanddatabequalitycontrolledanddistributed?

15. HowwillGrIOOSbefunded?

A synthesis from the workshop discussions is presented below. Discussion was focused onquestions1 through5,witha fewnotes frommore limiteddiscussionsonquestions6and7alsoincluded.

8

1.WhyestablishGrIOOS?Notwithstanding the advances in understanding ice/ocean interactions in Greenland, manychallengesremaininmodelingtheicedynamics,theice/oceanboundaryandtheoceanicshelfandfjords that connect the large-scale ocean to Greenland. In particular, modeled exchanges at theice/oceaninterfacearestillstronglydependentonparametersthathavenotbeenvalidatedbyfieldmeasurements including drag coefficients and turbulent exchange parameters for heat andfreshwater.Couplingof icesheetandocean/atmospheremodels is limitedand,where inplace, itrelies on oceanmodelswhich do not resolve the shelf and fjord processes. Parameterizations ofthese processes are needed to link ice sheet models (ISMs) with atmosphere-ocean generalcirculationmodels(AOGCMS).

The impact of meltwater discharge on the ocean and the marine ecosystems is still largelyunknown.TheexportofGreenlandmeltwaterintotheoceanoccursintheformofglaciallymodifiedwaters that are a mixture of meltwater and ambient waters. The characteristics of glaciallymodified waters depend on the details of processes at the ice/ocean boundary, which includeturbulentupwellingplumesdrivenbythereleaseofsurfacemeltatdepth,submarinemelting,andthe shape of the ice/ocean interface. These waters are subsequently further modified by fjordprocesses before being exported onto the shelves. None of these processes are currentlyrepresentedintheoceanmodels.EcosystemsaroundGreenlandarealsosensitivetovariationsinthe local water mass composition; changes lower down in the food chain can lead to dramaticchangeshigherup.

2.Whataretheessentialvariablestobemeasured?Ocean: Essential variables are temperature, salinity, and pressure in the fjord and nearby shelf.Bathymetryisalsoaneededinput.

Ice:Essentialvariablesaremeltwaterdischarge(surfaceandsubglacial),icevelocity,icethicknessand surface elevation, surface mass balance, mélange characteristics, calving behavior, andterminusposition.

Atmosphere: Essential variables are local winds and air temperature in the fjord and regionalatmosphericforcingoftheoceanandice.

A discussion of the extent to which these observations can be derived from existing networksand/orremotesensingispresentedbelow.

3.Whatmeasurementsexistalready?This section describes existing networks and projects that are collecting long-term data aroundGreenland. GrIOOS will build on these networks by incorporating relevant available data andpotentiallyleveragingsharedlogistics.ThenetworksaredescribedbelowandshowninFigure2.

A.AtmosphericAsiaqGreenlandSurvey isatwo-thirdsgovernmentfundedenterprisethatconductsmonitoringof hydrology, meteorology, ice surveys, and topographic mapping around Greenland, with anemphasisonthesouthwestcoastalregion.Theymaintainanetworkofautomaticweatherstations,

9

mostly locatedatairports,butalsoinsomemininglocationsandafewresearchsites.Locationofthe sites is dictated by hydropower needs, monitoring of drinking water for communities, andecological research (www.g-e-m.dk). It was noted that there is opportunity to leverage Asiaq’sannualsummermaintenancetripsforsharinglogistics.

PROMICE is a Danish government-funded monitoring network with the goal of providingconsistentlong-termobservationstocalculatemasslossbytheenergybudgetmethod.Itconsistsof>23automatedweatherstations(AWS)distributedintheablationzonearoundtheGreenlandIceSheet since 2007. The network has large spatial coverage and it is expected that it will bemaintainedlong-termformonitoringmasslossoftheicesheet.ThemaincomponentofPROMICEisthe free online database (www.promice.org) that includes historical mass balance data,documentation of recent change, and outreach efforts. In addition to the AWS, PROMICE hasconducted repeat airborneLIDAR/radar surveys around the icemargin in2007, 2011, and2015thathaveprovidedvelocitymappingandanauthoritativeicemask.

TheDanishMeteorologicalInstitute (DMI)maintainsanetworkofmeteorologicalstationswithassistance of aviation companies around themargins of Greenland (and at Summit Station). Thedataisavailableatwww.research.dmi.dk/dataandincludeshistoricalarchivesbackto1784.

B.SeismicandGeodesyTheGreenlandGPSNetwork,G-NET(polenet.org),systemmonitorstheearth’selasticadjustmentto ice loading and vertical accelerations. GNET began in 2007 and provides data on continentalupliftratesthatcanleverageothermoreexpensiveicemassbalancemethods(GRACEgravimetricinversions, repeat altimetry, and ‘Input-Output’ methods). The network consists of >50 nodesthroughoutGreenlandandanyonewithaGPSinstalledatafieldsiteisinvitedtojointhenetwork.

TheGreenlandIceSheetMonitoringNetwork(GLISN;www.glisn.info)iscomprisedofanetworkof33seismometers that canbeused todetectglacialearthquakesandcalvingevents, andseicheevents resulting from iceberg calving. Most stations are located in settlements near power andcommunicationresourcesandthusaregenerally>50kmfromglacierterminiandcanonlydetectthe largest events. The data are available in near real-time and work is ongoing to improveunderstandingoficebergcalvingmechanismsandmagnitudefromseismicrecords.

C.OceanMonitoringof oceanproperties around the continental shelvesofGreenland, and in the fjords, islimited.TheGreenlandicfisheriesindustryhasrecordsfrom1990ofbottomtemperaturecollectedduringbottomtrawlershrimpdensitysurveysoffthesouthwestcoast.Approximately50percentofthestationsarereoccupiedfromyeartoyear.TheIcelandicmackerelsurveyontheeastcoasthashydrographic measurements starting from 2013 that extends from Greenland to Iceland andNorway.

Monthly hydrographic transects have been conducted in Godthabsfjord since 2007 by GINR(Greenland Institute of Natural Resources) and include measurement of physical and biologicalvariables. Ice-free conditions in the fjord mean this survey is conducted year-round from smallvessels.Atonestation(GF3)nearNuukthereisasuiteofecosystemsamplingconductedinconcertwiththehydrographicobservations.EcosystemmonitoringisbeingcarriedoutonlyatafewothersitesaroundGreenland,butresourcesarelimitedandmarineecosystemobservationsonlybeginin2002.

The mooring array in Fram Strait to measure Arctic Outflow was deployed in 1997 as agovernmentfundedmonitoringsystemcollaborationbetweenNorwegianPolarInstitute(Norway)

10

and theAlfredWegner Institute (Germany).Thearrayrecords temperature, salinity, currents, icethicknessandicedrift,andiscomplementedbyannualCTD/LADCPandtracertransectsinAugustandSeptember.Itisexpectedthatitwillbemaintainedforatleastanother10years.ThemooringarrayisconcentratedindeeperwaterandlacksmooringsontheGreenlandiccontinentalshelf(duetoicehazards),howeverrepeatCTDtransectsareconductedontotheshelfwheneverpossible.Themooringarraypositionwasshiftedin2002causingajumpintheoceantemperaturetimeseries.

A mooring array across Davis Strait was deployed in 2004, as a USA-Canada collaborativeproject, to measure Arctic outflow west of Greenland. The mooring array spans across thecontinental shelves and measures velocity, temperature, salinity, sea ice thickness, and marinemammalacousticsandissupplementedbyyear-roundgliderobservationsandannualorbiennialhydrographicsections.Thefutureofthenetworkisuncertainanddependentonfunding.

Overturning in the SubPolar North Atlantic Program (OSNAP; www.o-snap.org) is aninternational trans-basin observing system to measure the Atlantic Meridional OverturningCirculation (AMOC) through mooring arrays, repeat hydrographic transects, and gliderdeployments. The observing network, which includes twomooring arrays on the southeast andsouthwestGreenlandshelvesandslopes,wasinstalledin2014andcurrentlyfundedthrough2018.Itisexpectedthatitwillbemaintainedfor10years.

Large scale ocean properties can be obtained from the ARGO float program that, since 2002,maintainsaglobalarrayofmorethan3000free-driftingprofilingfloatsthatmeasurehydrographicproperties in the upper 2000 m of the ocean. These floats are not useful on the Greenlandcontinental shelf but do provide boundary conditions tomonitor long-term average ocean basinpropertychangesaroundGreenland.

TheOceansMeltingGreenland(OMG)projectisa5-yearprogramthatbeganin2015toobservewatertemperaturesaroundthecoastofGreenlandandmeasurehowmarineterminatingglaciersreact to the presence of Atlantic Water. The project consists of annual aerial ice topographymeasurementsandgravimetryofglaciermarginsandthedeploymentof250AirborneeXpendableConductivity Temperature- Depth probes (AXCTDs) to measure the properties and extent ofAtlanticWater around the coast. As bathymetry is critical to understanding pathways to glaciertermini, the fjordsandcontinentalshelfwillbemappedwithairbornegravimetryandmultibeamsonar from surface vessels. This campaign will only provide a summer snapshot of waterproperties,butwillgreatlyimprovethespatialextentofmeasurementsaroundGreenland.

11

Figure2:ExistingnetworksonandaroundGreenland.

12

D.RemoteSensingGreenland Ice Mapping Project (GIMP) provides annual DEM and ice velocity datasets of theGreenlandIceSheetthroughtheuseofradaracquisition(e.g.,RADARSAT1,TerraSAR-X).Completecoverage of all major outlet glaciers exists from 2010-2012, and ice sheet velocity maps areavailablethrough2009/10and2012/13.DataareavailableonlinefromtheNationalSnowandIceDataCenter(NSIDC).

Landsat8datacanbeusedtoderiveicesurfacevelocitiesoveralargespatialareawitha16-dayrepeat period, however the optical satellite is dependent on atmospheric conditions (unlike theGIMP radarproducts).Acquisition is expected to rampup in2014and theproject isworkingonproducingnearreal-timedatastreams,butfuturefundingisuncertainatpresent.

Mass balance estimates of the Greenland Ice Sheet can be obtained from various sources,including gravimetry, geodetic, input-output and hybrid models. There are approximately 2.5decadesofdatawitheachmethodhavingdifferentstrengthsandweaknesses.Observationsbeginin1930sfromaerialsurveysandcontinue,withsignificantgaps,topresentfromsatelliteimageryand high-resolution laser and radar altimetry surveys, which can isolate glacier change fromsurfacemassbalanceversusoutletglacierdynamics.

Remote sensing products can be used to assess ice sheet accumulation and albedo. AirbornesurveyswithOperation IceBridge are useful butwith low spatial coverage and a relatively shorttime series (began in 2010 in Arctic). Changes in albedo are provided byMODIS satellite datacollectedalmostdaily(250mresolution).TheMODISdata is limitedbycloudyconditionsandbyimage geometry at high-latitudes, however it is a useful tool for understanding surface massbalanceprocesses.

OperationIceBridgeisthelargestairbornepolarsurveyandwasdesignedtofillthegapbetweenthe IceSat and IceSat-2 satellites. A variety of datasets are collected including LIDAR altimetry,radar,physicalmapping,surfacetemperature,gravimetryandmagnetism(forbedinversions),andatmospheric conditions. There is a largepre-melt (April-May) campaign, and a smallerpost-melt(October)campaign,andtheseareexpectedtocontinueuntil2019.AlldataareavailableonlineatNSIDC.

TheEuropeanSpaceAgency(ESA)hasastrongfocusoncreatingandmaintainingdataproducts.Keyparameters that aremonitored include surface elevation change, ice velocity, grounding linelocations,calving frontposition,andgravitymassbalance.Earlyproducts includehigh-resolutionvelocity maps from Jan-Mar 2015, complemented by repeat 12-day acquisitions of the marginssinceJune2015.

Remote sensing data products for oceanographic purposes include surface salinity at 60 kmresolution (Aquarius), and sea surface temperature (MODIS Aqua/Terra, AVHRR, Landsat 8, andblendedproducts likeOSTIA). Itwasnoted that someof theseproductsareuseful for fjord-scaleprocesses,suchassubglacialoutletplumes,sea-icecover,icebergdriftandbiologicalproductivity.Sea surface height can be measured via JASON-1/2/3, TOPEX-POSEIDON, ENVISAT/ERS, withlimitedcoverageathigh latitudes.SedimentplumescanbemonitoredbyMODISAqua/TerraandLandsat8,andoceancolorbySeaWIFS,MERIS,andVIRS.

4.Howmanyandwhichsitesshouldwestudy?Itisenvisionedthat5to10GrIOOSsiteswillbechosenandthatmeasurementswillcontinueforat

13

leastadecade.ChoiceofthesitesshouldtakeintoaccountexistingmeasurementsandsitesthatarealreadybeingmonitoredthatcouldbecomeGrIOOSsiteswithminimumadditionalmeasurements.Therewasgeneralconsensusthatthechosensitesshouldspanarangeofgeometriesthattakeintoaccount the glacier/fjorddepths, fjordswith andwithout sills, glacierswith andwithout floatingtermini, and different oceanic basins. Preferred sites are in close proximity to other observingnetworks(PROMICE,GNET,etc.),closetoinhabitedorregularlyservicedcentersforaccessibilityatreduced costs, and are of interest tomultiple disciplines. There should be a focus on the largestcontributorstoGreenlandIceSheetmassloss.Additionally,severalofthesitesshouldbeselectedtobuildonsitescurrentlytargetedforprocessstudiessothattheyaresimplyupgradedtosatisfystandardGrIOOSrequirements.Theproximityofpaleorecordsshouldalsobetakenintoaccount.

Avotingconductedduringtheworkshopidentifiedthefollowingsites.ThetopthreesitesselectedwereHelheim/Sermilik,79N/NEGIS,and Jakobshavn,withadditionalpriority sites listedhere inorderofvoting(Figure3):

1. Helheim/Sermilik – SEGreenland. Pros: representative of southeastGreenland, easy access,stabilizinggeometry,experienceatsiteandrelativelyextensiveexistingrecord,closetoOSNAPmooredarraysandOOIIrmingerSeanode.Cons:complexgeometryonshelfandinfjord,largemélange.

2. 79NandNEGIS(NortheastGreenlandIceStream)–NWGreenland.Pros:sciencecommunityexpectslargechanges,majoricestream,existingandplannedobservations,closetoFramStraitarray, floating tonguewhich can be used as a platform, an upstream ice core. Cons: remote,complexgeometry,difficultlogistics,accessibilityandlackofcommunityengagement,unusualgeology.

3. Jakobshavn–WGreenland.Pros:mostpotentialforretreatandcontributiontosealevelrise,easy access to ice, simple geometry, good long-term history. Cons: no high topography thatprovides an elevated view of the terminus, sill that limits Atlantic water, large and atypicalmélange,inaccessiblebyboat.

4. Petermann–NWGreenland.Pros:existingdataandongoingwork,easiertoaccessthan79N(debated), simple geometry, long-term record from paleo studies, ice shelf as platform, goodcliff viewing geometry for cameras. Cons: similar to 79N (debated), hard to access, small sealevelrisecontributor,NaresStraitmooringsaregone,atypicalofGreenland.

5. Rink–WGreenland.Comment:extensiveexistingmeasurements, currentlystablebutpoisedforretreat.

6. Kangerdlugssuaq–EGreenland.Comment:relativelyclosetoIceland,closetoDenmarkStrait,nolocalcommunity,existingmeasurements.

7. Upernavik–WGreenland.Comment:ongoingmeasurementsareoccurring.

8. Qanaaq–NWGreenland.Comment:ongoingJapaneseprogram,localcommunityinvolved.

9. GodthabsFjord–SWGreenland.Comment:hasongoingprogrambyGINR.

14

Figure3–SiteselectionbyvotingatGrIOOSWorkshop.

5.WhatistheoptimalinstrumentationandGrIOOSdesign?InstrumentationOcean:Oceanic instrumentationwill vary fromsite to sitedependingon the configurationof thefjordandtheglacier.Moorings($100-200k)willneedtobedeployedeitheranchoredtothebottomor suspended from a floating ice tongue, if appropriate. Pressure-inverted echosounders (PIES,$35k) provide an integral measure of heat content. Tagged seals carrying CTD sensors(conductivity,temperature,salinity)maybeagoodoptionforsomesites,althoughtheylastatmostoneyearduetomolting.

Ice:(“F”indicatesneededforfloatingtermini,“G”indicatesneededforgroundedornear-groundedtermini,$arepriceperunit)cameras(15minrepeatinterval)withinfraredcapability(G,$2-10k),seismic (1-3) for calving and subglacial discharge (F/G, $40k), Terrestrial Laser Scanner (TLS,G,$450k),GPS(F,$5k),phase-sensitiveradioechosounding(pRES)(F,$10k).

Atmosphere: AutomatedWeather Station (AWS, $20k) – 3 potentially,with one each on the ice(~1000m),attheterminus,andatthefjordmouth.

15

High temporal resolutionmeasurementsare required since it isunclearwhich timescalesgovernboththeoceanic forcingandtheglacierresponse.Theproposed instrumentation is inadditiontodataalreadyprovidedbyexistingnetworksandremotesensing.

DesignThegroupheardaboutanddiscussedlessonslearnedfrompreviousobservationprograms,suchasPROMICE.OneresourcedocumentreferencedistheNASAFrameworkforOceanObserving.Withinthediscussion,severalpotentialkeycharacteristicswereidentified:

• Light is sustainable: Logistically or instrumentally expensive observing systems are verydifficult tomaintain over time. Simple logistics, and ones thatwouldmake use of interestedcommunities,arebest.However,previousefforts(e.g.,USGSmonitoringformountainglaciers)haveshownthatitisbesttoaimforoversamplingduringthefirstseveralyearsoftheobservingsystem, with the objective to identify key sites for sustained observations, accommodatingpotentialneedstoscaledowntheobservingsystemovertime.

• Monitoring requires proven technology: Although testing new technology is an interestingprospectifitcanreducelatercosts,anobservingsystemisnotthebestplacetoimplementnewtechnologies.

• Buildonavailable logisticsandprograms:Althoughprogramsthatarealreadyrunningwouldnot easily scale up, they can provide logistical support for additional instrumentationdeployment,ifnecessary.

6.Howwillmeasurementsanddatabequalitycontrolledanddistributed?Therewasadiscussionofgovernanceanddatasharing.Minimumrequirements foranobservingnetwork includea framework for:1.keyvariables tobemeasured,2.dataqualitypoliciesand3.datasharingpolicies.Severaldifferentpossibleframeworkswerediscussed.AONrequiresdatatobe immediately available. PROMICE demonstrates that this is important, valued and successful.Quickandcentralizedaccesstodataiskey,thoughthereshouldbeflexibilitysothatcountriesarenotexcludedfromtheGrIOOSprocessforembargoreasons.Itwasalsopointedoutthatitmightnotbeworthwhiletoberigidaboutrulesbeforethereisevenanyfunding.

Discussionrecognizedthatanobservingsystemneedstohavestrongdataservercapabilitieswhereobservations can be exchanged, as well as means of defining the success and impact of theobserving system itself. Cloud solutionswerementioned as a potentially useful tool. Apart fromtypicalacademicmeasuressuchaspublicationsandcitations, itwasproposed to introduceothermeasures of success, for example by recording the uptake of data from the data server, andrecordingwhoisusingtheobservations(e.g.,academia,industry,otherstakeholders).

7.HowwillGrIOOSbefunded?Workshop attendees heard from Eric Lindstrom (NASA) and William Ambrose (NSF ArcticObserving Network) about recommendations for funding strategies, but did not lay out specificplansforGrIOOSfunding.EricLindstromemphasizedtheimportanceofinterdisciplinaryresearchanddevelopmentofdatamanagementandanalysisplansthatalsoincorporatepreviouslycollecteddata and data collected by other funded projects.WilliamAmbrose discussed the AON Program,which ismeant tocomplimentandprovidecontext forprocess studies.AON isaproposaldriven

16

programand,atthistime,roughlyaquarteroftheprojects(bynumber)arephysicaloceanography,aquarteratmosphericsciences,andaverysmall fractionlandice.Healsodiscussedthepotentialvalue of partitioning GrIOOS efforts into standalone projects, the value of involving younginvestigators,andtheopportunitiesandchallengesintransatlanticcoordination.

SummaryRapid ice loss from theGreenland Ice Sheet is, in part, attributed to ocean forcing at themarinemargins of Greenland’s outlet glaciers. Yet our understanding of the mechanisms leading to theobserved glacier retreat (and hence the ice loss) are poorly understood. On the ocean side,increasediceandfreshwaterdischargefromtheGreenlandicesheetiscontributingtosealevelriseandafresheningoftheNorthAtlantic,withimportantconsequencesforoceancirculationandthemarineecosystem.Understandingandpredictingtheimpactofoceanandatmospherechangesonthe ice sheet and, vice versa, of ice sheet changes on the ocean is hindered by our limitedunderstandingandabilitytomodelprocessesattheglacier/oceanboundaryandtheirconnectionto the larger scale ocean, ice and atmospheric. One important gap identified by the communityworking in and around Greenland is the lack of the long-term data from glacier/fjord systemsaroundGreenland.Thus,ithasbeenproposedthataGreenlandIceSheet/OceanObservingSystem(GrIOOS)beestablishedwiththegoalofcollectinglong-termdataatanumberofkeysitesaroundGreenland. The goal of GrIOOS is to informunderstanding and provide boundary conditions andvalidationformodels.

Here, the preliminary conclusions on how to design and establish such a network, following aninternational workshop held in December 2015, are presented. GrIOOSwill consist of ~10 siteswhosecharacteristicswillcoverarangeofglacier/fjordconfigurations,differentoceanicbasinsandclimatic regimes. Essential measurements to be collected at these sites include oceanic(temperature,salinity,pressureinthefjordandnearbyshelf),glaciological(icevelocity,thickness,meltwaterrunoff,mélangecharacteristics,terminusvariations,calvingbehavior)andatmospheric(local winds and air temperature on the glacier and nearby fjord). Bathymetry and bedrock areneeded inputs foranyGrIOOSsite.Paleomeasurements toprovide temporalcontextarestronglydesired.A series of~10 sites are proposedbasedon a number of criteria including existing andongoingprograms,proximitytonetworknodesandrelevancetothemotivationdescribedabove.

ThedevelopmentandmaintenanceofGrIOOSwillrequirecloseinternationalcollaboration.GrIOOSimplementationwillneedtobecoordinatedamongstdifferentcountries,payingcloseattentiontominimizing costs and optimizing shared logistics. Data processing protocols and data sharingpractices will be identified. Quick and centralized access to data is key, though there should beflexibilitysothatcountriesarenotexcludedfromtheGrIOOSprocessforembargoreasons.

17

ReferencesArrigo,K.R.,Dijken,G.L.,Castelao,R.M.,Luo,H.,Rennermalm,Å.K.,Tedesco,M.,...&Yager,P.L.(2017).MeltingglaciersstimulatelargesummerphytoplanktonbloomsinsouthwestGreenlandwaters.Geophys.Res.Lett.,44,doi:10.1002/2017GL073583. Bamber,J.,M.vandenBroeke,J.Ettema,J.Lenaerts,andE.Rignot,2012:RecentlargeincreasesinfreshwaterfluxesfromGreenlandintotheNorthAtlantic.Geophys.Res.Lett.,39(19),L19501.doi:10.1029/2012GL052552

Enderlin,E.M.,I.M.Howat,S.Jeong,M.J.Noh,J.H.Angelen,andM.R.Broeke(2014),AnImprovedMassBudgetfortheGreenlandIceSheet,GeophysResLett,doi:10.1002/(ISSN)1944-8007.

Heimbach, P., F. Straneo, O. Sergienko, and G. Hamilton, 2014: International workshop onunderstanding the response of Greenlands marine-terminating glaciers to oceanic andatmospheric forcing: Challenges to improving observations, process understanding andmodeling.June4-7,2013,Beverly,MA,USA.USCLIVARReport2014-1,USCLIVARProjectOffice,WashingtonDC,20006.

Joughin, I. and B.E. Smith, 2013: Further summer speedup of Jakobshavn Isbræ. The CryosphereDiscuss.,7,5461-5473.doi:10.5194/tcd-7-5461-2013

Joughin, I., R.B. Alley, and D.M. Holland, 2012: Ice-sheet response to oceanic forcing. Science,338(6111),1172–1176.doi:10.1126/science.1226481

Lenaerts,JTM,D.LeBars,L.vanKampenhout,M.Vizcaino,E.Enderlin,M.R.vandenBroeke,2015:Representing Greenland ice sheet freshwater fluxes in climate models. Geophys. Res. Lett., 42,doi:10.1002/2015GL064738.

Marsh,R.,D.Desbruyères, J.L.Bamber,B.A.deCuevas,A.C.Coward,andY.Aksenov,2010:Short-term impacts of enhanced Greenland freshwater fluxes in an eddy-permitting ocean model.OceanSci.,6(3),749–760.doi:10.5194/os-6-749-2010

Moon,T.,I.Joughin,B.Smith,andI.Howat,2012:21st-CenturyevolutionofGreenlandoutletglaciervelocities.Science,336(6081),576–578.doi:10.1126/science.1219985

Moon,T., and I. Joughin, 2008: Changes in ice frontpositiononGreenland’s outlet glaciers from1992to2007.J.ofGeophys.Res.,113(F2),F02022.doi:10.1029/2007JF000927

Price, S. F., H. Conway, E.D. Waddington, and R.A. Bindschadler, 2008: Model investigations ofinland migration of fast-flowing outlet glaciers and ice streams. J. Glaciol., 54(184), 49–60.doi:10.3189/002214308784409143

Rignot,E.,andP.Kanagaratnam,2006:ChangesinthevelocitystructureoftheGreenlandIceSheet.Science,311(5763),986–990.doi:10.1126/science.1121381

Shepherd,A.,E.R.Ivins,A.Geruo,V.R.Barletta,M.J.Bentley,S.Bettadpur,etal.,2012:Areconciledestimate of ice-sheet mass balance. Science, 338(6111), 1183–1189.doi:10.1126/science.1228102

Straneo,F.,P.Heimbach,O.Sergienko,G.Hamilton,G.Catania,S.Griffies,etal.,2013:ChallengestounderstandingthedynamicresponseofGreenland’smarineterminatingglacierstooceanicandatmospheric forcing. Bull. Amer. Meteor. Soc.,94(8), 1131–1144. doi:10.1175/BAMS-D-12-

18

00100.

Straneo, F., et al., 2012: Understanding the dynamic response of Greenland’smarine terminatingglacierstooceanicandatmosphericforcing.AwhitepaperbytheUSCLIVARWorkingGrouponGreenland Ice Sheet Ocean Interactions (GRISO), Report 2012-2, US CLIVAR Project Office,Washington, DC, 22pp, available at http://www.usclivar.org/sites/default/files/GreenlandIceOcean_WhitePaper.pdf.

van den Broeke, M., J. Bamber, J. Ettema, E. Rignot, E. Schrama, W.J. van de Berg, et al., 2009:Partitioning recent Greenland mass loss. Science, 326(5955), 984–986.doi:10.1126/science.1178176

vandenBroeke,M.R.,E.M.Enderlin, I.M.Howat,P.KuipersMunneke,B.P.Y.Noël,W. J.vandeBerg,E.vanMeijgaard,andB.Wouters(2016),OntherecentcontributionoftheGreenlandicesheettosealevelchange,TheCryosphere,10(5),1933–1946,doi:10.5194/tc-10-1933-2016.

Vieli, A., and F.M. Nick, 2011: Understanding andmodelling rapid dynamic changes of tidewateroutletglaciers:Issuesandimplications.Surv.Geophys.,32(4-5),437–458.doi:10.1007/s10712-011-9132-4

Weijer, W., M.E. Maltrud, M.W. Hecht, H.A. Dijkstra, and M.A. Kliphuis, 2012: Response of theAtlantic Ocean circulation to Greenland Ice Sheetmelting in a strongly-eddying oceanmodel.Geophys.Res.Lett.,39(9).doi:10.1029/2012GL05161

19

AppendixI:ListofAttendees

SteeringCommitteeMembers

1. Abermann(Asiaq,Greenland)

2. Ahlstrom(GEUS,DK;glaciologist)

3. Hamilton(UMaine,USA;glaciologist)

4. Heimbach(MIT/UTexasUSA;oceanmodeler)

5. Nowicki(GISS,NASA,USA;icesheetmodeler,ISMIP)

6. Scambos(NSIDC,USA;SEARCH;remotesensing,Antarctica)

7. Straneo(WHOI,USA;SEARCH,oceanographer,Greenlandice/ocean)

8. Sutherland(U.Oregon,USA;oceanographer,Greenlandice/ocean)

Facilitator

9. BobBindschadler(SEARCH,glaciology,NASA,USA)

Others

10. MikeBevis(OhioSU,USA;GNet)

11. LauradeSteur(NPI,NO;ocean,FramStrait,Greenlandice/ocean)

12. AqqaluRosing-Asvid(GINR,Greenland;marinebiologist)

13. HollandD(NYU,USA;ice/ocean)

14. MortensenJ.(GINR,Greenland;oceanographer)

15. IanJoughin(APL-UW,USA;iceremotesensing)

16. BeathaCsatho(U.Buffalo,USA;remotesensing)

17. MarcoTedesco(CUNY,USA;surfacemassbalance)

18. AsaRennermalm(Rutgers,USA;hydrology)

19. AlunHubbard(Aberystwth,UK;glaciologist)

20. MarkInall(SAMS,UK;oceanographer)

21. AdrianJenkins(BAS,UK;ice/ocean)

22. LeighStearns(KansasU,USA;glaciologist)

23. GinnyCatania(U.Texas,USA;glaciologist)

24. ShinSugiyama(Hokkaido,Japan;glaciologist)

25. ErinPettit(UAF,USA;acousticsforice)

26. DaveFinnegan(CRREL,USA;engineering;LIDAR)

20

27. SridharAnandakrishan(PSU,USA;glaciology)

28. AlanMix(OregonSU,USA;paleo)

29. ChristianRodehacke(DMI,DK;icesheetmodeling)

30. LoraKoenig(NSIDC,USA;hydrology,Icebridge)

31. IrinaOvereem(NSTAAR,USA;sedimentplumes)

EarlyCareer(Sindicatestudents,Ppostdoc)

32. DavePorter(LDEO,USA;ice/ocean)

33. PierreDutrieux(APL-UW,USA;ocean/ice,DavisStrait)

34. IanFenty(JPL,NASA;USA,OMGNASA)

35. TwilaMoon(U.Oregon,USA;glaciology/remotesensing)(P)

36. AndrewHamilton(UBC,CA;glacier/ocean,AUVs,Canadianglaciers)(S)

37. TimBartholomaus(UTIG,USA;seismic,radars,glaciology)

38. AlistairEverett(Swansea,UK;glaciology)(S)

39. KristinSchild(Dartmouth,USA;,remotesensing,sediment)(S)

40. RebeccaJackson(WHOI/MIT,USA;oceanography)(S)

41. EllynEnderlin(U.Maine,USA;glaciers,icebergs,remotesensing)

42. TomCowton(U.Edinburgh,UK;oceanmodeler)(P)

43. MaureenWalczak(OregonSU,paleo)(P)

Programmanagers

44. EricLindstrom(NASA)

45. WilliamAmbrose(NSF)

GreenlandicGovernmentRepresentative

46. InuuteqHolmOlsen(MinisterPlenipotentiaryforGreenlandtotheUSA)

Arcusonsitecoordinator

47. LisaSheffieldGuy

21

AppendixII:MeetingAgenda

SaturdayDecember12th

ISMIP6participantswilljoinusinthemorningsessions.

8:30-9:00breakfast

9:00-10:40Session1:WhyanObservingSystem

Reviewofbasicunderstandingoficeforcingoceanandviceversa;identifythelong-termneeds.

Chairs:PatrickHeimbach;IanJoughin

Notetakers:AlistairEverett,IanFenty

1.IntroductionandGoals(Straneo,20min)

2.Glacierretreat/advance–(G.Hamilton/T.Moon–10min)

3.Oceanforcingglaciers

i)Theory/Modeling/Observationsofsubmarinemelting(A.Jenkins;10min)

ii)IcesheetModeling:Impactofoceanvariability(T.Payne,20min)

4.Glaciersforcingocean(Sutherland/Heimbach,10min)

5.Atmosphericforcingofglaciersetting–(A.Ahlstrom,10min)

6.Impactofglacierchangesonthemarineecosystem–(A.Rosing-Asvid,10min)

10:40-11:00CoffeeBreak

11:00-12:30Session2:Whathavewelearned-glacier/fjordprojects?

Chairs:FiammaStraneo;GordonHamilton

Notetakers:TomCowton,KristinSchild

Briefreviews(3slidesmax)ofglacier/fjordexperiments

• Ummanaq(Catania)

• NuukFjord/Glacier(Mortensen)

• StoreGlacier(Hubbard)

• Upernavik(Ahlstrom)

• Bowdoin(Sugiyama)

• Alison/Hayes(Porter)

• Qanaaq–(RodehackeDMI)

• Helheim/SermilikF.(Straneo/Hamilton)

• 79North–(Straneo)

• Kangerlugssuaq(Inall)

22

• Jakobshavn(Holland)

• Petermann–(Mix)

Lunch12:30-1:30

1:30to3:00Session3:ExistingMeasurements

Summaryofexistingnetworks,monitoringsites,airborneandremotesensing(2slidesperprogram)

Chairs–DaveSutherlandandTwilaMoon

Notetakers:MaureenWalczakandAndrewHamilton

Insitu:

• Asiaq(Abermann)

• PROMICE/GCNET(Ahlstrom)w.airbornework

• GNet(Bevis)

• DMIMetStations(Rodehacke),

• Fisheriesdata(Rosing-Asvid),

• FramStrait(deSteur),

• DavisStrait(Dutrieux)

• OSNAP(Straneo)

• ARGO(Straneo)

• GLISN(Bartholomaus)

• Nuuk/Zackenbergmonitoringsites(Mortensen)

• BaffinBayObservatory(FutureCanadian/EU/Greenland)–(Mortensen)

• DenmarkStrait(?)–Inallfutureplans

Remotesensing/airborneassets

• Landsat/SAR(Moon/Joughin)

• Massbalance/elevationchanges(Csatho)

• SurfaceMassBalance/SurfaceMelt(Tedesco)

• Oceanicremotesensing(Sutherland/Heimbach)

• Icebridge(Koenig)

• ESA’sClimateChangeInitiative(Alhstrom)

23

Mixed

• OMG–NASA(Fenty)

CoffeeBreak3:00-3:30

3:30-5:00Session4:BreakoutI

ThreegroupbrainstormingforGrIOOS.

Whatmeasurementsareneeded?Where,howmanyandhowdotheytietoexistingnetworks.

5:00-8:00–ReceptionJointwithISMIP(IceSheetModelingIntercomparisonProject)

SundayDecember13th

8:30-9:00breakfast

9:00-10:00Session5SummaryfrompreviousdayincludingBreakoutI

ChairsJakobAbermann;DavidSutherland

Notetakers:EllynEnderlin,PierreDutrieux

10:00-11:00Session6ProgrammanagersInput(TBA)

ChairP.Heimbach

Notetakers:RebeccaJackson,KristinSchild

10:30-11:00Coffee

11:00-12:30Session7MeasurementTechniques

Reviewinstrumentation/measurementtechniquesincludingfeasibility/costs.

Chairs:GordonHamilton,TedScambos,AndreasAhlstrom

Notetakers:AndrewHamilton;DavePorter

12:30-13:30Lunch

13:30–15:00Session8BreakoutSessionII

BreakoutagainintothreegroupsandcontinuebrainstormingGrIOOS.

Whatisfeasible,whatinstrumentation,whatwillitcost?

Contrastwhatiseasytomeasure/whatisimportant

Producetableofeasyversusimportant(includecosts)

Discusswhattechnologyismissing

15:00-15:30Coffee

15:30–17:00Session9SummaryDiscussion/presentationofthe3groups

DiscussionleadBobBindschadler

Notetakers:RebeccaJacksonandTimBartholomaus

24

AppendixIII:NotesfromeachsessionSession1-AlistairEverettandIanFenty

1.IntroductionandGoals(Straneo,20min)

FShighlightedtheaimsofGrIOOS.GrIOOSfollowsonfromthepreviousGRISOworkshop,andrepresentsoneofthefourprioritiesoutlinedinthecurrentGRISOreport.Importantly,GrIOOSshouldimproveunderstandingofthelinksbetweentheice,oceanandatmosphere;helptoimproveboundaryconditionsformodels;andleaveausefullegacyofdataforfuturegenerations.

WiththisinmindFSposedanumberofquestions:

• Whatmeasurementsareessential?• Whatisalreadythere?• Howmanyandwhichsitesshouldwestudy?• Howwilldatabequalitycontrolled?• Whatoptionsarethereforfunding?• WhattimescalesshouldGrIOOSbeinterestedin?• Howwillmeasurementsanddatadistributionbecoordinated?

2.Glacierretreat/advance–(G.Hamilton/T.Moon–10min)

GHhighlightedremotesensingasakeytoolinunderstandingspatialandtemporalpatternsofadvanceandretreatinGreenland’sglaciers.Wenowhavearecordspanningafewdecades,withspatialresolutionsrangingbetween~15-250metres/pixel.Manytechniqueshavebeendevelopedforextractingicefrontpositionsandvelocitiesfromtheseimages.

MoonandJoughin(2008)showarecordofterminuspositionsseparatedintotwoepochs1992-2000and2000-2006.Moreglacierswereinretreatduringthelaterperiod.TheoverallretreatiscontemporaneousintheSEandNWsectors.Arelativelylargeseasonalcycleisalsofoundinmanyglaciers.Longertermrecords(eg.Bjorketal.,2012)alsoshowaperiodofretreatinthe1930sand‘40s,followedbysomeadvancethroughthe‘70sand‘80s.

TM highlighted existing research on forcings such as climatic (eg. ocean/atmosphere) andenvironmental(eg.fjordbathymetry,melange).TMshowedaninverserelationbetweenspeedandterminusposition.

East Greenlandic behaviour is divided around the 69N latitude (Seale et al.,2011),with differentbehaviourtotheNandS,likelyrelatedtodivergenceoftheIrmingerCurrentattheDenmarkStrait.TMsummarisedrecentbehaviourof floatingtongues:ZachariaeIsstromrecently lost its iceshelf,TMsuggestedthat79Nmightbethenexttogo,Petermanischaracterisedbylargecrevassesandmaysoonseeanadditionalshelfbreakup.

3Oceanforcingglaciers

25

i)Theory/Modeling/Observationsofsubmarinemelting(A.Jenkins;10min)

AJpresentedareviewofcurrentunderstandingoftheocean-iceinterface.Physicsoftheturbulentice-oceanboundarylayerbeneathseaiceisfairlywellobservedandunderstood.Verticalandhorizontalicefacesworkonbroadlysimilarprinciplesandtheoryshouldbegenerallyapplicable.Meltratescanbecalculatedfromthethreeequationparameterisationwhichincludesthebalanceofheatandsaltacrosstheice-oceanboundarylayerandconstrainstheicesurfacetobeatthepressuremeltingpoint.Thethreeequationmodelcanbeincorporatedintoplumetheorytomodelmeltratesdrivenbytheconvectionofsubglacialdischarge.

AJhighlightedthreecharacteristicregimeswhichoccurataverticaliceface,wherewewouldgenerallyexpectmeltonthescaleofGreenlandicglacierstobeinthehighestregion–ontheorderofz>~100m.Inthisregimemeltratesincreasewithheight.AJhighlightedthedifficultyofcarryingoutlabscaleexperimentswithinthisregime,andthereforeonvalidatingcurrentmodels.

AJoutlinedanumberofunknownswhicharecurrentlyassumedforapplicationofplumetheory.Theseincludetheentrainmentoftheplume,thedragcoefficient,andtheturbulentexchangeparametersfortemperatureandsalinity.Duetothedifficultyoflabscaleexperimentsandlimitedobservationstheseparametersareeffectivelyuntested.

Observationsofbasalmeltratesexistonfloatingicetonguesusinghighprecisionradar,butverticalfacesaremuchmoredifficult.Acousticsoundingseemsliketheonlyoption,buttherearequestionsaboutwhetheritissufficientlyaccuratetocapturemeltrates,andhigh-temporalresolutionwillbenecessarytoresolvechanges.Otherquestionsremainaboutthecouplingofplumetheorytothemeltrateparameterisation,currentlythisreliesonthebulktemperatureandsalinityoftheplume,butthismaynotaccuratelyrepresent‘far-field’conditionsfortheice-oceanboundarylayer

Recentstudies(Xuetal,2012;Sciasciaetal,2013;Kimuraetal,2014)haveappliedhighresolution,non-hydrostaticoceanmodelstotheverticalicefaceproblem,butintheabsenceofobservation,resultsaretunedtomatchplumetheory.

ii)IcesheetModeling:Impactofoceanvariability(TonyPayne,20min)

TPsummarisedcurrenteffortstobringicesheetmodellingtotheCMIP[coupled-modelintercomparisonproject]process,currentlyISMIP6.Atpresent,CMIPmodelshaveaverypoorrepresentationoficesheets.ImportantfeedbacksbetweentheicesheetsandtheoceanarenotcapturedwhichlimitstheutilityofCMIPmodelprojectionsofsealevelrise.

Twomethodsarecurrentlyused:icesheetforcedbyatmosphericandoceanicboundaryconditionsandicesheetcoupledwithinanatmosphere/oceanmodelwithfeedbacksbetweenthetwo.Boundaryconditionsareparticularlydifficulttoparameteriseinicesheetmodels(ISMs),AOGCMsdonotresolveshelfandfjordprocesses,thereforeaparameterisationisnecessarytolinkICMstoAOGCMs.

TPdiscussedissueswithresolvingoutletglaciersandtheeffectsofgridresolutiononmodel

26

predictions.ISMsarenowbeginningtoincludeimprovedmodelsofcalvingandfrontalmelt.TPhighlightedthestronglinksbetweenGrIOOSandISMIP6efforts,andhowGrIOOSmaybeimportantininformingtheparameterisationsusedtolinkISMstoAOGCMs.

4.Glaciersforcingocean(Sutherland/Heimbach,10min)

DSsummarizedglacier-oceaninteractionsfromthefjordscale(~1km)tothebasinscale(~1000km).

Onthefjordscale,liquidfreshwater(eg.Subglacialdischarge,surfacerunoff,submarinemelt)andsolidfreshwater(eg.icebergs)dischargesaffectfjordcirculationpatterns,withfeedbacksbetweenfjordconditions(eg.buoyancydrivenflows,T/Smodification)andicefrontprocesses(eg.Calving,submarinemelt).Otherglacialimpactsonfjordcirculationincludeforexampleaseasonalorpermanenticemelange,andmixingdrivenbydeep-keeledicebergsmovingwithinfjords.

OnbasinscalesfreshwateraffectslargescaleprocessessuchastheAMOC.WhilethevolumeoffreshwaterreleasedintothearcticoceanfromGreenlandissmallcomparedtoriverdischarge,thedepthandpropertiesofwaterintroducedattheboundariesofAOGCMshasastrongimpactontheresults,andiscurrentlypoorlyunderstoodleadingtomajoruncertaintyinmodelresults.Forexample,someAOGCMShavesuggestedthatfreshwaterinputfromGreenlandcanreducetheAMOCbyaround50%(10Sv),whileothermodelswiththesameforcingshowdifferentresults.

5.Atmosphericforcingofglaciersetting–(A.Ahlstrom,10min)

AAoutlinedanumberoffeedbackmechanismsbetweentheicesheetandtheatmosphere.Atmosphericdriversofincreasedsurfacemeltingincludewind,whichcanalsoaffectthestabilityofproglacialicemelange,increasedrainfallandsolarradiation.Otherfactors,suchascrevasseextent,canhavefeedbacksonsurfacemeltingthroughincreasesinsurfacearea.Increasedsurfacemeltandrainfallcanencouragehydrofractureandinputsofmeltwatertothebed.Thetransferofwatertothebedincreasesbasalwaterpressuresleadingtosliding,andalsodrivesfeedbacksattheterminus,whereincreasedsubglacialdischargeleadstomorerapidsubmarinemeltwithpotentialimpactsoncalvingandterminusstability.

6.Impactofglacierchangesonthemarineecosystem–(A.Rosing-Asvid,10min)

AR-AdiscussedimpactsofchangesinoceancurrentsandincreasedfreshwaterinputsfromtheGrISonlocalecosystemsaroundthecoastlineofGreenland.Benthicorganisms,atthebaseofthefoodchain,varywithdistanceup-fjordandalsobetweenadjacentfjords.Manyaresensitivetolocalwaterproperties,krillforexampledonotsurviveinpolarwater.Thechangingboundariesoflocaloceancurrentsthereforehasastrongimpactonlocalecosystems.Changeslowerdownthefoodchaincanleadtodramaticchangeshigherup.Inthe1930stheexpansionofhigharcticconditionsledtoCapelinmovingnorthwhichinturnledtoincreasednumbersofHarpSeals.Morerecently,anincreasingnumberofmackerelhavebeenfoundoffthesoutheastcoastofGreenland,inadditiontoincreasednumbersofcapelinandherring,makingthesewatersmoreviableforcommercialfishing.

27

ItisthoughtthattheserecentchangesmaybedrivenbythemigrationofatlanticwatersclosertothecoastlineofGreenland.

AR-Aalsohighlightedtheusefulnessofsealtaggingforgatheringoceanographicmeasurements,successfulcampaignshavealreadybeencarriedoutaroundthecoastlineofGreenlandcollectingprofilesoftemperatureandsalinityoneachdive.Thistechniqueintegratesbiologicalandoceanographicobservationsandthereforemaybedesirableforattractingawiderrangeofstakeholderstoanobservingsystem.Testinghasalsobeencarriedoutonherringtagging,whichmayproveaviabletechniqueinfuture.

28

Session 2: What have we learned- Glacier/Fjord Projects?

TomCowton&KristinSchild

Ginny Catania – Central West Greenland (Rink/UMI/KS)

Projectgoals-determinetheoceancontributiontotheobservedheterogeneityinglacierdynamics

Projectlocation-15glaciersoverthepast3yearsonthecentralwestcoastofGreenland

Structure:

1. Remotesensingprogramforentireregion(Landsat,WorldviewDEMs)2. FieldprogramonRink/UMI/KSglaciersystems(3glaciers)3. Modelingtheinterfacebetweentheiceandoceansystems

Results-highlycontrolledbygeometry

Variabilityinsystems:

• Someinretreat,someshowlittlechange• Somelosingmass,somegainingmass• Someshowstablevelocity,whileothersshowfluctuations• KShasalargesubmarinemoraine–mightneedtoresurveybathymetry• Multi-beamterminusprofilesshowthatmeltratesarelargerthanmodelssuggest• FjordcirculationfrommooringsatRinkandKS

o Rinkhasenergetic,seasonallyfluctuatingsubsurfaceoutflowo KSisshallower,andsohassurfaceoutflowo Monitoringnearsurfacewatersdifficultduetoicebergs

Lessonslearnt:

1. Spatio-temporalvariabilityinthesesystemsisthenorm–itmaybebettertostudymoresystemsthanoneinparticulardetail

2. Itiscriticaltohavebathy/beddata–tounderstandgeometryanditsimportanceandformodeling,andhowtheselocalconditionsmodulateglacierbehavior.

3. Improvedin-situobservationsareneededtodeterminethespatio-temporalvariabilityin:1)subglacialdischarge;2)fjordtemperature/salinity;3)submarineterminusgeometry(morethanonceperyear!)

Alun Hubbard – Store Glacier

Context,glacierbackground

29

• Calvingfront~5kmwide&upto500mdeep,freeboardat120m• AnnualELA-gatemassfluxof~16-18GT/a• Calvingfrontfluxof~14GT/a&peakterminusvelocityto30m/d• Stableicefrontpositionsinceearly1900sthoughmodulatedbyseasonalfrontal

advance/retreatcycleof~500m• Dynamicthinningrateof~1.5m/asince1990s.• Modelled,measured&inferredsubmarinemelting~2to8m/d,somebigupwellingareas• Silldepthof450mabout80kmfromterminus,fjorddepth~800m• AWis2.4-2.8Cyearround

Methods

• Boreholedrilled30kmupglacierfromterminus(SAFIREproject)• LIDARsurveyingoficefront(hasn’tworkedwellduetolaserproperties)• CTDmeasurementsinsummerandwinter• Side-scansonarofcalvingfront(revealspresenceofplumesanddeeplyundercutareas)• Seismics,radar,andGPSsurveysalsoconducted

Results:Highlyheterogeneousacrosstheterminus-lotsofvariability.

John Mortensen- Godthabsfjord

Background:PermanentstationnearNuuk,andmultipleCTD(andADCP?)stationsalongfjord.Lookingatthecirculationandtidalmixinginthefjordmouth.

Results:

• Clearsignalofbuoyancy-drivencirculation–fjordoutflowisstrongerandshallowerduringsummer

• Tidalexchangewithshelf(5mtidalrange),andmixingoversill,areimportant• Windsblowup-fjordduringsummermonths,whichresultsinextensivemelangecoverin

upperfjordsincetherearenokatabaticwindshere.

Andreas Ahlstrom- Upernakik Isstrom (4 glacier system)

Background:4glaciersdrainingintoheadofsamefjord-experiencingacommonatmosphericforcingandsimilarfjordwaterproperties,butshowdifferentindividualresponseduetolocalbathymetryandgeometry(e.g.eachoutletisatadifferentdepth)

Methods:

• Bathymetricmapping(includingfromhelicopterinmelange)

30

• High-frequencysatellitevelocitymapping• 2PROMICEAWS• TimelapsecameralookingatUP-1• On-glacierGPS-trackers(down-glacier)• GNETGPS• Differentialon-glacierGPS(up-glacier)• CTDandsedimentcores• ISSMmodelling(basalfriction)

Suggestions:

• GreatersharingofCTDdatawouldbevaluable• Createacollectionofsedimentcoresfromthefjordtoreconstructcalvingratesandwater

temperatureovera100yeartimeperiod(ledbyCamilllaAndresen).• Alsowouldliketohavebathymetrydatabeforecorecollection.

Shin Sugiyama – Bowdoin Glacier (also Qaanaaq region, NW Greenland, ~20 glaciers)

Background:QaanaaqvillageisaccessiblebyAirGreenlandflight(1perweek).Studyhasbeenongoingfor5years,andhasbeenextendedforafurther5years

Results/Futurework:

• 20glaciersinregions,allshowretreatfrom~2000.BowdoinGlacierhasbeenstablesinceatleast1949,butbegantoretreatin~1999.Therateofretreatacceleratedin2008.

• TheterminusofBowdoinGlacierisaccessibleinasmallboat.Bathymetrysurveyedalongfjordcentrelineandsomecross-fjordtransects.Aimingtoestablishamooring&CTDmeasurements.

• Glaciersurfacealsoaccessibletowithin~1kmofcalvingfront.Hotwaterdrilling2kmfromicefront.

David Porter – Alison Glacier

Background:PilotstudyconductedinJuly2014,toworkwiththecommunity(villageofKullorsuaq)totakeoceanographymeasurements.Relativelyaccessible(inrangeofAirGreenlandhelicopter).Fjordistypicallymelange-filled.Bigretreatin2003.

Methods/Results:

• Localknowledgeusedtomapfjorddepth(latercorroboratedbyOMGmulti-beamsoundings).Gravityinversionindicatessill~15kmfromcalvingfront.Thelocalfishermenestimatedthefjorddepthtobe~1000m,whichisveryclosetogravityresults.

• 17CTDstationstakenfromasmallfishingboatover2days.Onlyobtainedtodepthof450mduetolengthofrope,butfjord1000mdeepinplaces.

31

• Suggestsnon-specialists(e.g.fishermen)canmeasurenearbyfjordwaterproperties.Inwinter,thiscouldbedonethroughsealholes.Thecommunitymembersareinterestedincontinuingthemeasurements.

Christian Rodehacke – Tracy Glacier (North Greenland/Qaanaaq region fjords)

Background:SampledLatewinter(April/March)hydrographysince2011throughcollaborationwithDanishmilitary

Sciencequestion:Whataretheconditionsattheendofwinter/beginningofsummernearTracyGlacier?

Plan(August/September2015-17):

• SimpleCTDprogram,limitedwatersampling.• RelyonsupportfromtheDanishArcticCommand(notyetapproved2016-17)• Focusonthelatesummerheatcontentandstratification(pre-conditioning)• PossibilitytocoverfurtherglaciersystemsintheNaresStrait:HumboldtandPetermann

glacier• Willuseturbidityasameasurementofglacialwater

Exampleresults–canidentifyturbidmeltwaterjetat~50mdepthatBowdoinGlacier.Shallowwarmsurfacewaterisflowingdownfjord.Sedimentplumesexistatthesurfaceinfrontoftheglacier-subglacialdischargeisbuoyantenoughtoreachthesurface.

Mark Inall – Kangerdlugssuaq Fjord

Summaryofstudies(lotsofmeasurementsinthefjord):

• 1993:CTD• 2004:CTD,AUVabsvel,LADCP(v.limited),bathymapping,O18(unpublished)• 2008:CTD+75kHzVMADCP,troughsectiononly• 2009/10:CTD/XBT,MooringT150-300m• 2010:CTD,microstructure–shelfonly(unpublished)• 2011:CTD,microstructure,0-30mabs.vel.• 2015:Seaglider,outershelfonly• NSIDCseaice1992–present• VariousSSTproducts• Glacierfront/speed(Luckman,unpublished)1985-present• Morerecentinsituobs?Straneogroup?• Hydrodynamicmodels:

Ø BOM,3D(2012,CryosphereDiscussions)Ø MITgcm2D(2013,JGR2013)–idealised,notspecificallyKangerd.

32

Ø MITcgm3D(2015,unpublished)

Summaryoffindings

• SGDcanvarymeltbyfactor10(seasonal,model)• 4cellcirculationschemecan/doesexist(obs+model)• EstimatesofAW-inducedmeltratesvarybyfactorof~10(obs+model)• PSWisveryimportantinanumberofways• Shelfflowsarehighly3D(model)• Fjordentranceflowsare3D(obs+model)• Trough:importanttopographicsteering(obs),andlargetroughexistsatKGL.• Windresponseiscomplexand3D–pulsingofAWandPSWwbywind(obs+models)–a

fewCTDcastsmaynotberepresentativeofconditions

• ThecomplexityofoceanwatertravelingtothefjordisstillTBD.

David Holland – Jakobshavn Isfjord

StateofKnowledge:

• Deepwaterinsidefjordisreplacedbylessdensewaterfromoutsidefjord.Thiswouldn’thappeninanon-glacialfjord,andislikelyduetoentrainmentintoplumesatice-oceaninterface.

• Fjordwaterpropertiesaredeterminedbywaterpropertiesatsilldepth.Insummer,AWisthickerbutcoolerthanwinter.Itisthiswaterthatflowsoversillintofjord.Theamountofwarmwaterinthefjordvarieseveryseason.

• Alighterwatermasscancomeintothefjordandreplacethedenserwater.Thisflushingoccursbecausethesubglacialdischargeresultsinbuoyantplumes.

Methods:HavehadsuccesswithCTDfromboatandhelicopter,butnotmoorings(issueswithicebergsandfishery).Gliderfromboatandtaggedmammalscouldhavepotential.

Ian Joughin – Jakobshavn Isbrae

StateofKnowledge:

• Glacierthickens10-15minwinterandthins~30minsummer,net-15m/yr.• ThefastestJakobshavnvelocities(2010-2015,peak2012)occurredduetoungroundingof

theglacierterminusandsubsequentretreatacrossatopographiclow.

Differentmodesofretreatareimportant:

33

1. Transienttriggering–forcingdrivesretreatofterminusfromstableposition,beyondwhichretreatisself-sustainingandmaynotreflectongoingforcing.Lateralresistanceisresponsibleforaslowdown.

2. Sustainedforcing–ongoingforcingrequiredtodriveretreatofglacier

Alan Mix – Peterman Glacier

ProjectGoal:tostudynotjusttriggersofpastretreat(usingPaleomethodsandSedimentcores)butalsodynamicsduringthisretreat.

Overviewofstudylocation/newdatasets:

• Petermanhaswell-constrained,simplegeometry:Floatingiceshelf50-kmx15-km,high-resolutionbathymetry(NEW),deepCanyon750-kmintointerior.

• Icetopography&drainage:Basalchannels1-2kmx40kmlong,surfaceponds,streams,crevasses,similartoWestAntarcticsystems

• Documentedviabilityofpaleorecords:Paleogroundinglines(NEW),Paleosea-levelrapidretreat(NEW),~60Sedimentcores(NEW),documentdecadalvariability.

• ManageableLogistics:ThuleAirForceBaseassciencehub,NewDanishinvestments,AccessviaAirNationalGuard,WithinRange;Helicopter,TwinOtter

Results:

• IceBridgealtimeter&radarrevealsiceshelfthinning<5m/year2003-2010,>5m/year2007-2010.Calvingin2010,2012removed28kmiceshelf(36+4Gt)

• Warmingbottomwaters,fresheningofsurfacewaters(pop-upmoorings,~20units,poppingupovernextfewyearsthenturnintodrifters):Regionalscale-Warmingalongisopycnals2003-12,Localscale-warmerandsaltierAtlanticinflow2012-15.Waterhaswarmed~0.1Csince2003.Theglacierresponse:coolerfresheroutflow2012-15

• Canidentifyoldgroundinglineandsedimentwedgewithbathymetrydata-thereboundismuchfasterthaninexistingmodels.AlsofoundclamshellswheretheicewassupposedtobeduringtheLGMaccordingtoreconstructions,soLGMreconstructionsarealsoinaccurate.

On-goingdatacollection:

• Observationsonandbelowiceshelf(AWS):3through-icestationswithoceanmoorings,On-goingreal-timeoceanproperties(>100days,hourlymeasurements),Bi-monthlyvariabilityinice-oceanboundarylayer

• AlsodatingofraisedbeachesusedtoreconstructisostaticreboundFiamma Straneo – 79N Glacier, draining NE Greenland Ice Stream

Background:LargestfloatingicetongueinGreenland-groundedin600m,withoceancavity80km

34

long.Glacierishardtoaccessduetolandfastseaice.CTDcastsundertakenin1992and2009,withsomebyhelicopter.

Futurework:Measurementsareplannedfortrough,cavityandlandicein2016/17withAWI,NPI,WHOI…

Fiamma Straneo – Sermilik Fjord

Methods:X-CTDcastsandmooringswithinfjord(Marchsurveyandsummersurvey)

Results/Suggestions:

• Thereisagreaterspatialvariabilityinsummer.Needtobecarefulwithwheremeasurementsaretaken.Formeasurementstakendistantfromthecalvingfront,needatransferfunctiontoconvertfornearglacierproperties.Measurementstakennearglacieralreadyincludetheeffectsofice-oceaninteraction,soneedtobecarefulthatthesepropertiesaren’tduplicated.Weneedtobeknowwhatwearesamplingandwhatwearenotsampling.

• Alsomuchtemporalvariability–can’tjustrelyonsummermeasurements,astheytendtobesnapshotssensitivetoexternalforcingandglacierdischargeandarenotadequateorrepresentativeofthesystem.

• Arguesthatwedon’tyetknowwhatweneedtomonitoraswedon’tfullyunderstandprocessesofice-oceaninteraction–muchdatamaybecomemoreusefulasweimprovethisunderstanding.

• Presently,unbiasedmeasurementsoftheglacier-oceanlinkandrealisticsubmarinemeltingmeasurementsarenottrivial.

35

SummaryofSession3:ExistingMeasurements

Rapporteurs:MaureenWalczakandAndrewHamilton

SpecialpresentationpriortocommencingSession3

EricLindstrom(NASA,USA)

EricistheProjectManagerfortheGlobalOceanObservingSystem(GOOS).Hestressedtheneedforanindependentlyinitiatedobservingsystemtogetorganizedinordertomakethebestcasepossibletoobtainfunding,andherecommendedthatGrIOOSutilizetheFrameworkforOceanObserving(FOO;http://www.ioccp.org/foo)asaguideforbestpractices,essentialoceanvariablestomonitor,andasatemplateforcommonlanguageutilizedinobservingsystems.Hestressedtheneedtotranslatethequalitysciencecurrentlybeingconductedintoacomprehensiveobservingsystemthatprovidessustainedinterdisciplinary(physical/biological/chemical)observationstoaddresssocietalneeds.Itisimportantthatallstagesoftheprojectareincludedinthedevelopmentoftheobservingsystem,especiallythecriticalneedfordatamanagementanddevelopmentofendproductsthatclosetheloopbacktoansweringtheoriginalquestionsthatmotivatedthecreationoftheobservingsystem.

Session3:ExistingMeasurements

Summary:EighteenspeakersgaveabriefintroductiontomeasurementthatarecurrentlybeingcollectedaroundGreenlandthatcouldbeleveragedand/orincludedinGrIOOS.Thepresentationsweredividedinto4groups:1)Atmospheric,2)SeismicandGeodesy,3)Oceanographic,and4)RemoteSensing.

1. AtmosphericJakobAbermann(Asiaq,Greenland):Asiaq/GEM

AsiaqGreenlandSurveyisatwo-thirdsgovernmentfundedenterprisethatconductsmonitoringofhydrology,meteorology,icesurveys,andtopographicmappingaroundGreenland,withanemphasisontheregionfocusedonthesouthwestcoast.Theymaintainanetworkofautomaticweatherstations,mostlylocatedatairports,butalsoinsomemininglocationsandafewresearchsites.Thesitesaredictatedbyhydropowerneeds,monitoringofdrinkingwaterforcommunitiesandecologicalresearch(www.g-e-m.dk).ItwasnotedthatthereisopportunitytoleverageAsiaq’sannualsummermaintenancetripsforsharinglogistics.

AndreasAhlstrom(GEUS,DK):PROMICE

PROMICEisDanishgovernmentfundedmonitoringnetworkwiththegoalofprovidingconsistentlong-termobservationstocalculatemasslossbytheenergybudgetmethod.Itconsistsof>23automatedweatherstations(AWS)distributedintheablationzonearoundtheGreenlandIceSheetsince2007.Thenetworkshavelargespatialcoverageandareexpectedtobemaintainedlong-termformonitoringmasslossoftheicesheet.ThemaincomponentofPROMICEisthefreeonline

36

database(www.promice.org)thatincludeshistoricalmassbalancedata,documentationofrecentchange,andoutreachefforts.Theyconductedrepeatairbornelidar/radarsurveysaroundtheicemarginin2007,2011,and2015,aswellasprovidevelocitymappingandanauthoritativeicemask.

ChristianRodehacke(DMI,DK):MeteorologicalandRemoteSensingfromDMI

TheDenmarkMeteorologicalInstitute(DMI)maintainsanetworkofmetstationswithassistanceofaviationcompaniesaroundthemarginsofGreenland(butalsoatSummitStation).Thedataisavailableatwww.research.dmi.dk/dataandincludeshistoricalarchivesbackto1784.Itwasnotedthatitisespeciallyimportantforuserstonotifythenetworksiftheyusethedataasthisimproveschancesforcontinuedfunding,particularlyforthestationsintheNEGreenlandthataredifficultandexpensivetoaccess.

2. SeismicandGeodesy

MikeBevis(OhioStateU,USA):GNET

TheGNETGPSsystemwaspresentedanddiscussedhowitisutilizedforglacier-oceaninteractionmonitoringbysensingearth’selasticadjustmenttoiceloadingandverticalaccelerations.GNETbeganin2007andprovidesdataoncontinentalupliftratesthatcanleverageothermoreexpensiveicemassbalancemethods(GRACEgravimetricinversions,repeataltimetry,and‘IN-OUT’methods).Thenetworkconsistsof>50nodesthroughoutGreenlandandanyonewithaGPSinstalledatafieldsiteisinvitedtojointhenetwork.TheutilityoftheGNETnetworkasmeteorologicalsensorswasalsopresented.

TimBartholomaus(UTIG,USA):GLISN

TheGreenlandIceSheetMonitoringNetwork(GLISN)iscomprisedofanetworkof33seismometersthatcanbeusedtodetectglacialearthquakesandcalvingevents,andseicheeventsresultingfromicebergcalving.Itwasnotedhoweverthatmoststationsarelocatedinsettlementsnearpowerandcommunicationresourcesandthusaregenerally>50kmfromglacierterminiandcanonlydetectthelargestevents.Thedataisavailableinnearreal-timeandworkisongoingtoimproveunderstandingoficebergcalvingmechanismsandmagnitudefromseismicrecords.

Discussion:EricLindstromcommentedthattherewassignificantoverlapbetweentheGLISNandGrIOOSnames,whichcouldcauseconfusionamongthefundingagencies,andapotentialnamechangeforGLISNtoincludetheterm‘seismic’wouldbeworthconsidering.

3. Oceanography

AqqaluRosing-Asvid(GINR,Greenland):FisheriesandMarineBiology

TheGreenlandicfisheriesindustryhasrecordsfrom1990ofbottomtemperaturecollectedduring

37

bottomtrawlershrimpdensitysurveysoffthesouthwestcoast.Approximately50percentofthestationsarereoccupiedfromyeartoyear.ItwasnotedthattheIcelandicmackerelsurveyontheeastcoasthashydrographicmeasurementsstartingfrom2013thatextendsfromGreenlandtoIcelandandNorway.OverallthereisnotalotofoceanicmonitoringoccurringaroundGreenland.

JohnMortensen(GINR,Greenland):GINROceanographyandGreenlandEcosystemMonitoring

MonthlyhydrographictransectshavebeenconductedinGodthabsfjordsince2007andincludemeasurementofphysicalandbiologicalvariables.Ice-freeconditionsinthefjordmeanthissurveyisconductedyear-roundfromsmallvessels.Atonestation(GF3)nearNuukthereisasuiteofecosystemsamplingconductedinconcertwiththehydrographicobservations.EcosystemmonitoringatafewothersitesaroundGreenland,butresourcesarelimitedandmarineecosystemobservationsonlybeginin2002.

LauradeSteur(NPI,Norway):FramStraitMooringArray

ThemooringarrayinFramStraittomeasureArcticOutflowwasdeployedin1997asagovernmentfundedmonitoringsystemcollaborationbetweenNorwegianPolarInstitute(Norway)andtheAlfredWegnerInstitute(Germany).Thearrayrecordstemperature,salinity,currents,icethicknessandicedrift,andiscomplementedbyannualCTD/LADCPandtracertransectsinAugustandSeptember.Itisexpectedtobemaintainedforatleastanother10years.ThemooringarrayisconcentratedindeeperwaterandlacksmooringsontheGreenlandiccontinentalshelf(duetoicehazards),howeverrepeatCTDtransectsareconductedontotheshelfwheneverpossible.Itwasnotedthatthemooringarraypositionwasshiftedin2002causingajumpintheoceantemperaturetimeseries.

PierreDutrieux(APL,USA):DavisStraitMooringArray

AmooringarrayacrossDavisStraitledbyCraigLee(APL,USA)wasdeployedin2004tomeasureArcticoutflowwestofGreenland.Themooringarrayspansacrossthecontinentalshelvesandmeasuresvelocity,temperature,salinity,icethicknessandmarinemammalacousticsandissupplementedbyyear-roundgliderobservationsandannualorbiennialhydrographicsections.Thefutureofthenetworkisuncertainanddependentonfunding.

FiammaStraneo(WHOI,USA;SEARCH):OSNAP,ARGO

OverturningintheSubPolarNorthAtlanticProgram(OSNAP;www.o-snap.org)isamultinationaltransbasinobservingsystemtomeasuretheAtlanticMeridionalOverturningCirculation(AMOC)

38

throughanextensivemooringarray,repeathydrographictransectsandgliderdeployments.Theobservingnetwork,consistingoftwomooringarraysextendingwestandeastfromthesoutherncoastofGreenland,wasinstalledin2014andisexpectedtobemaintainedfor10years.

TheARGOfloatprograminitiatedin2002isaglobalarrayofmorethan3000free-driftingprofilingfloatsthatmeasurehydrographicpropertiesintheupper2000moftheocean.ThesefloatsarenotusefulontheGreenlandcontinentalshelfbutdoprovideboundaryconditionstomonitorlong-termaverageoceanbasinpropertychangesaroundGreenland.

IanFenty(JPL,NASA,USA):OceanMeltingGreenland(OMG)

TheOMGprojectisa5-yearprogramtoobservewatertemperaturesaroundthecoastofGreenlandandmeasurehowmarineterminatingglaciersreacttothepresenceofAtlanticWater.Theprojectconsistsofannualaerialicetopographymeasurementsandgravimetryofglaciermarginsandthedeploymentof250AirborneeXpendableConductivityTemperature-Depthprobes(AXCTDs)tomeasurethepropertiesandextentofAtlanticWateraroundthecoast.Asbathymetryiscriticaltounderstandingpathwaystoglaciertermini,thefjordsandcontinentalshelfwillbemappedwithairbornegravimetryandmultibeamsonarfromsurfacevessels.Adesiretocoordinatewithotherprojectstostrategizedeploymentlocationswasexpressed.Itwasnotedthatthecampaignwillonlyprovideasummersnapshotofwaterproperties,butwillgreatlyimprovethespatialextentofmeasurementsaroundGreenland.

JohnMortensen(Greenland):BaffinBayObservatory

TheBaffinBayObservatoryisaproposedcollaborationbetweenCanada,theEU,andGreenlandthatwouldconsistofamooringarrayandcabledobservingsystem.Itisanobservationalsystemdesignedtocomplimentsatellitedatawithafocusonbiogeochemicalcycling.Littleinformationonthefundingandtimeframewasavailable.

MarkInall(SAMS,UK):OSNAP

ThisisaproposaltoextendtheElletLine(E3L;NorthAtlanticCirculationandClimate)transectfrom2018usingsurfacevesseleverytwoyearsandgliderseachyearinthewinter.ThesectionwouldbeanextensionoftheO-SNAPprojectacrosstheDenmarkStraitbetweenIcelandandGreenland.Anoverviewofexistingobservationswasgiven,includinganotethatobservationsbeganin1975.

4. RemoteSensing

IanJoughin(APL-UW,USA):GreenlandIceMappingProject(GIMP)

Throughtheuseofradaracquisition(RADARSAT1,TeraSAR)theprojectprovidesannualDEMandicevelocitydatasetsoftheGreenlandIceSheet.Thereexistscompletecoverageofallmajoroutletglaciersfrom2010-2012,andicesheetvelocitymapsareavailablethrough2009/10and2012/13.

39

DataareavailableonlinefromNSIDC.

TwilaMoon(U.Oregon,USA):LandSat8SurfaceVelocities

Provideicesheetsurfacevelocitiesoveralargespatialareawitha16-dayrepeatperiod,howevertheopticalsatelliteisdependentonatmosphericconditions(unliketheGIMPradarproducts).Acquisitionisexpectedtorampupin2014andtheprojectisworkingonproducingnearreal-timedatastreams,butfuturefundingisuncertainatpresent.

BeathaCsatho(U.Buffalo,USA):GreenlandMassBalance

AnoverviewofmassbalanceestimatesoftheGreenlandIceSheetweregivenfromvarioussources,includinggravimetry,geodetic,input-outputandhybridmodels.Thereareapproximately2.5decadesofdatawitheachmethodhavingdifferentstrengthsandweaknesses.Observationsbeginin1930sfromaerialsurveysandcontinuetopresentfromsatelliteimageryandhigh-resolutionlaserandradaraltimetrysurveys,whichcanisolateglacier,changefromsurfacemassbalanceandoutletglacierdynamics.

MarcTedesco(CUNY,USA):SurfaceMassBalanceandMelt

Asummaryofremotesensingofproductstoassessicesheetaccumulationandalbedoweregiven,witharelationofthestrengthsandlimitationsofthemethods.AirbornesurveyswithOperationIceBridgeareusefulbutwithlowspatialcoverageandarelativelyshorttimeseries(beganin2010inArctic).Thepointwasraisedthatsurfacemassbalancemodelsrequiresnowdensitywhichisnotacquirewiththesedatasets.AlsopresentedwerechangesinalbedoprovidedbyMODISsatellitedatacollectedalmostdaily.TheMODISdataislimitedtocloud-freeconditionsandbygeometryofimagesathigh-latitudes,howeveritisusefulpartofunderstandingsurfacemassbalanceprocesses.

LoraKoenig(NSIDC,USA):OperationIceBridge

AsummaryofIceBridgewithafocusonradarproductswaspresented.IceBridgeisthelargestairbornepolarsurveyandwasdesignedtofillthegapbetweenIceSatandIceSat-2.AvarietyofdatasetsarecollectedincludingLIDARaltimetry,radar,physicalmapping,surfacetemperature,gravimetryandmagnetism(forbedinversions),andatmosphericconditions.Itwasrelatedthatthereisalargepre-melt(April-May)campaign,andasmallerpost-melt(Oct)campaign,andtheseareexpectedtocontinueuntil2019.AlldataareavailableonlineatNSIDC.

40

AndreasAhlstrom(DEUS,DK):EuropeanSpaceAgency

ThepresentationprovidedasummaryofEuropeanSpaceAgency(ESA)remotesensingproductsandclimatechangeinitiative.Itwasemphasizedthatthereisastrongfocusoncreatingandmaintainingdataproducts(notjustdatarepository).Keyparametersthataremonitoredincludesurfaceelevationchange,icevelocity,groundinglinelocations,calvingfrontposition,andgravitymassbalance.Earlyproductsincludehigh-resolutionvelocitymapsfromJan-Mar2015,complimentedbyrepeat12-dayacquisitionsofthemarginssinceJune2015.

DaveSutherland(U.Oregon,USA):RemoteSensingforOceanography

Abriefsummaryofvariousremotesensingdataproductsforoceanographicpurposeswasgiven,includingsurfacesalinityat60kmresolution(Aquarius),andseasurfacetemperature(MODISAqua/Terra,AVHRR,LandSat8,andblendedproductslikeOSTIA).Itwasnotedthatsomeoftheseproductsareusefulforfjord-scaleprocesses,suchassubglacialoutletplumes,sea-icecover,icebergdriftandbiologicalproductivity.SeasurfaceheightcanbemeasuredviaJASON-1/2/3,TOPEX-POSEIDON,ENVISAT/ERS,withlimitedcoverageathighlatitudes.SedimentplumescanbemonitoredbyMODISAqua/TerraandLandSat8,andoceancolourbySeaWIFS,MERIS,andVIRS.

Discussion:

BobBindschadler(SEARCH,USA)

Thegroupwasencouragedtokeepinmindotherstakeholdersthatwouldbeinterestedinthedataproducts(beyondtheglacierandoceanscientificcommunity)andalternativefundingsourcesforGrIOOStoleverage.Therewasarecommendationtoconsiderothervalueaddedproductsthemonitoringsystemcouldproduce,withaparticularnoteforpredictiveproducts–whichcouldbeinformedbywhattheocean-ice/climatemodelersneedtoimprovetheirmodels.

41

NotesfromSession5–Summaryfrompreviousdayincludingbreakouts

PierreDutrieux

Theassemblywasfirstremindedthatadocumentsummarizesbestpractices/policyforproposingobservingsystemandnetworks:theFrameworkforOceanObserving(NASAdocument).

Adiscussiononlessonslearnedfrompreviousprograms(e.g.PROMICE)followed.Alistofkeycharacteristicsforasuccessfulprogramis:

• 'Lightissustainable':logisticallyorinstrumentallyexpensiveobservingsystemsareverydifficulttomaintainovertime.Thatbeingsaid,itmightbewisetostartthefirstfewyearsoftheobservingsystemwithoversampling(ashasbeendonebyUSGSformonitoringmountainglaciers,forexample)withtheobjectivetoidentifykeysitesforsustainedobservationsandtoscaledowntheobservingsystemafterafewyears.

• 'Monitoringrequiresproventechnology':althoughtestingnewtechnologyisaninterestingprospectifitcanreducecostsfurtherdowntheline,anobservingsystemisnotthebestplacetoimplementnewtechnologies.

• 'Buildonavailablelogisticsandprograms':althoughprogramsthatarealreadyrunningwouldnoteasilyscaleup,theyprovidelogisticalsupportforadditionalinstrumentationdeployment,ifnecessary.

• Simplelogistics,andonesthatwouldmakeuseofinterestedcommunities,isbest.

Tomotivateprogressinunderstandingandprovideanswersrelevanttosociety,theissueoftheobservingsystemintegrationwithmodellingactivitieswasraised.So:whatwouldthemodellerswant?

• Whatwouldbeneededtopredict/forecast/increaseourunderstandingofthesystemoverdecadaltimescales?Impactofoceanforcingontheice?Impactoficemeltingontheocean?Theproblemisthattheanswertothisquestionstronglydependsonourstilllimitedunderstandingoftheprocessesthemselves.

• Whatwouldbiologicalmodellersneed?Theassemblyfellshortofdefininganswerstothosequestions.

Finally,itwasrecognisedthatanobservingsystemneedstohavestrongdataservercapabilities(Cloudsolutions?)whereobservationscanbeexchanged,aswellasmeansofdefiningthesuccessandimpactoftheobservingsystemitself.Apartfromtypicalacademicmeasures(publicationsandcitations),itwasproposedtointroduceothermeasuresofsuccess,forexamplebyrecordingtheuptakeofdatafromthedataserver,andrecordingwhoisusingtheobservations(academia,otherstakeholders?).

42

GrIOOS Session 6: Program Managers input

Notes from Becca Jackson & Kristin Schild

Eric Lindstrom – NASA (presented Sat 12 December 2015)

Tipsforgettingproposalsfunded(specificallymonitoringproposals):

• Show/tellwhatyou’vedoneandwhyyouneedtocontinuemonitoring• Theproposalneedstobeinterdisciplinary• Goodwordstoinclude/whattheyliketoseeistimedevotedto“datamanagementand

analysis”.Theywouldfundaproposaljusttodothis.ThereisalotofcollectedNASAimagery/datathatisjustsittingthere-collectedbytheirmissionsandfundedprojects.

• Thesciencetraceabilitymatrix(FOO[addwebsite])outlineswhattoincludeinaNASAproposal.

William Ambrose – director of Arctic Observing Network (AON) at NSF.

AON’smission:detectandquantifyArcticchange,withabroadrangeofprogramsincludingindigenouscommunity,physicalandbiologicaloceanography,permafrost,etc.

AONProgram&whattheyfund:

• Itisaproposaldrivenprogram,sovisioniselusive.Theprogramisnotreallyanetwork,andthereismissionflexibility.

• PIsneedtohavequestionsinmindastheydeveloptheirproposals,butitisnotforhypothesis-drivenresearchordataanalysis.Itdoesfundsupportforobservinginfrastructure,addingobservinginfrastructure,innovativeobservingtechnology,etc.

• AONismeanttocomplimentandprovidecontextforprocessstudies.CurrentlythereareAONsitesallaroundtheArcticandGreenland,andthereisadatabaseonline[addwebsite]–allthedataisopenlyavailableimmediatelyaftercollection.

Fundingstatistics:

• CurrentlyAON’sportfoliois,bynumberofproposals:aboutaquarterphysicaloceanography,aquarteratmosphericsciences,andaverysmallfractionlandice.Thesmallnumberoflandiceprojectsislikelyduetofewproposalssubmitted.

• TherewasalargejumpinAONfundingin2009fromARRA.Manyoftheproposalsfundedduringthisperiodandcomingupforrenewalnow.AlotofAON’scurrentbudgetistiedupin“mortgage”forongoingprojects,buthopefullythiswillbereducedinfuture.Incurrentfundinground,AONhasreceived$75millioninfundingrequests,withon$5-6milliontospend.

Suggestionsforgettingproposalsfunded:

43

• GrIOOShastobepartitionedandpitchedtovariousfundingagencies.NSFlikesgrassrootseffortsandworkshops.Proposalsshouldbeabletostandalone,whilealsobeingpartofacoordinatedGrIOOSeffort.NSFrecognizesthevalueoflong-termmeasurements,buttheyneedtohavegoodquestions.

• Younginvestigatorsareencouragedtobeinvolved,makeconnectionsandwritejointproposalswithotheryounginvestigators,intheUSandabroad(UKmentioned)

• Issuesraisedabouttransatlanticcoordinationandjointprograms,especiallythetimingandoutcomesforproposals.ThereisaNERCagreementthatallowsthemtoletNSFdothereviewanddecideonfundingdecisionforjointproposal(USandUK).

Questionaboutroadmapforbigprojectsandproposals:howtocobbletogetherpieces?Thereisnoformalmechanismforjointreview,evenbetweenUSagencies.Itissuggestedtotalktoprogrammanagers.Leveragingco-fundingisgood(e.g.betweenNSFandNASA)andeverybodywins,butproposalsalsoneedtobeabletostandalone.

Question:whyislandicesuchasmallpieceofAONfunding?Likelynotmanyproposalsfunded,othersourcesoffundingforthesethings.

44

SummaryofSession7:MeasurementTechniques

Rapporteurs:AndrewHamiltonandDavePorter

Summary:

Inthissession12speakerspresentedanoverviewofmeasurementtechniquesusedtostudyglacier-oceaninteractionsinGreenland.Theadvantagesanddisadvantagesofeachinstrumentwerediscussed,andlogisticalandbudgetaryconsiderationsrelated.Therewasanemphasisonrelativelyinexpensivebutessentialinstrumentsandmeasurementtechniquesthatcouldbeincludedatexistingfieldsitestorecordkeyvariablesfortheobservingsystem.Whenavailablecostshavebeenincludedintheinstrumentationsummary.Thepresentationsweredividedintotwogroupsdependingonthefocusofobservation:1)Iceand2)Ocean.

1.IceMeasurementTechniques

TedScambos(NSIDC,USA):AMIGOS-II

Aprototypeglacier-oceanobservingnode,AMIGOS-2,waspresented.ThenodeconsistsofanIridiumsatellitetelemeteredsurfacestationwithmet/GPS/cameralinkedtoathrough-iceDistributedTemperatureSensor(DTSfiberopticcable),andoceanographicsensorsbelowtheice,including2CT-cellsand2currentmetersandahydrophone.ThesystemispoweredbyLi-ionbatteriesandsolarpanelsandisdeployedwithanadjacentADIOSGPSpolethatlinkstothesurfacestation.Theunitisintendedtobedeployedthroughaniceshelfwithahotwaterdrillandtherearecurrently15ofitspredecessor(AMIGO-I)deployedacrossAntarcticaandhavefunctionedfor3-4years.

Cost:$160k(additionalCT/currentmetersensorclusters$30keach)

SridarAnandakrisnan(PSU,USA):Activeseismometers

Smallself-containedactiveseismicsystemswerepresented,usefulformappingiceshelfcavities,bathymetry,andsedimentstructure(requiredforgravimetryinversions).Thesystemsareeasilydeployablefromhelicopters,appropriateforcrevassedglacierterrain,andusefulforobtainingsedimentthickness,soundvelocities(thatcaninformdensityestimates),groundtruthgravityinversions,andidentifygroundedorfloatingice.Over150systemshavebeendeployedworldwide.

Cost:unknown

TimBartholomaus(UTIG,USA):PassiveSeismicStations

Theutilityofpassiveseismometersatglacierterminifordetectingsubglacialdrainagesignalsand

45

calvingeventswaspresented.Thesystemsarerelativelylowcostandrobust,requiringatmostannualservicing,yethavetheabilitytoimproveunderstandingofverypoorlyobservedsubglacialdrainageprocessesandcandetectevensmallcalvingeventswhendeployedclosetotheterminus.Workisongoingtocalibratetremorswithdrainagevolumeorintensity.Whencombinedwithhydrophones,timelapsecamerasandtidegaugestheseismometerswouldgiveacompletepictureofepisodiceventsinglacialfjords.Theseismicstationsarebatteryandsolarpoweredandonlyrequire3-4hoursforinstallationwithonehourofannualservicing.

Cost:<$40k/yrperstation

ErinPettit(UAF,USA):AcousticObservationsofGlacialFjords

Passivehydrophoneshavebeenutilizedforapplicationsrelatedtosubmarinemeltrates,calvingevents,subglacialdischarge,seicheevents,andmarinemammals.Thehydrophonesarerelativelylowcostbutdorequireannualservicingdueinlargeparttomemorycapacitylimitationsduetothelargedatasetproduced(e.g.marinemammalfrequenciesrequiresamplingat>5kHz).

Cost:$6-10k($20kforbroaderspectrumsystems)

DaveFinnegan(CRREL,USA):AutomatedTerrestrialLaserScanner(ATLAS)

Astand-aloneautomatedLiDARsystemwith6-11kmrangeusedtocreatehighresolutionDEMSwaspresented.TheATLASsystemprovidesa60ofieldofview(withenvironmentalenclosure),15mmaccuracyand10mmprecision(spotsdensityfallsto1minfar-field).Thesystemrequires24VDCand600WattHrsperscanbutwillbepoweredsolelybymethanolfuelcellssufficientfor1-yearoperation.Thesystemprovidesamassivedataset(~30millionpoints)usefulforanalyzingterminusadvance,tidalmotion,icemélange,andcalvingevents.AsystemwasinstalledinJuly2015atHelheimGlacier,setat30minscanevery6hoursresultingincompressed200Mbfile.Datastorageoverayeardeploymentwouldbeanmajorissue

Cost:$450k

GordonHamilton(U.Maine,USA):TimelapseCamerasandThermalImaging

Abriefpresentationoftimelapsecameraswaspresented,notingthelow-costsystemsareusefultomeasurecalvingevents,terminusposition,presenceofsubglacialplumes,andconditionoficemélange.ThesystemsaStarDot5MPwebcamand/orFLIRandareIridiumtelemeteredforreal-timeviewingandpoweredby12DCsolar.Forinfraredotherinformationisrequired,includinghumidity,calibrationtemperatures,andopticaldepths.

Cost:$2-10k(visiblevsinfrared)

46

AlistairEverett(Swansea,UK):RemoteSensingofSubglacialPlumes

Aphotogrammetricmethodofusingseasurfaceheightanomaliestoestimatedischargeandvolumefluxofsubglacialplumesthatrisetothesurfacewaspresented.ThemethodrequiressomeCTDwatercolumndatabututilizesexistingremotesensingproductsandassuchrequiresnoadditionalinvestmentorinfrastructure.Themethodislimitedinthatitrequiresavisiblesurfaceexpressionoftheplume,andisthereforeimpactedbyicemélangeandfjordstratification,andresultsinaprobabilityofdischargemaximumthatmustbeconstrainedwithotherdata.

Cost:none

2.OceanMeasurementTechniques

DaveSutherland(U.Oregon,USA):OceanographicMooringsandIcebergTracking

Deepsubsurfaceoceanmooringsweredescribedwithmodificationsforthechallengingenvironmentofglacialfjordswithiceberghazardsandhighsedimentationrates.Mooringsincludevarioussensorssuchascurrentprofilers(ADCPs),temperaturesensors,conductivity-temperaturesensors,pressuresensors,andIridiumbeacons,butarefullyadaptableforinclusionsofothersensors.Someadaptationsincludeddualacousticreleasemechanismsforredundancy,weaklinksintheupperpartofthemooringincaseoficebergencounters,andmid-waterflotationtoreducelikelihoodofdragbyicebergkeels.Thesignificantchallengesofmaintainingmooringsinglacialfjordswereemphasized,andicebergsgenerallyprohibitmeasurementsintheupper50-100mofthewatercolumn.Mooringsareusualdeployedfor2yearsandsamplingintervalsdependonsensorsbutareusually<1hr.Deepwatermooringsrequirelargevesselstodeploywithassociatedship-timecosts.

Cost:$100k-$300k

Shallowpop-upmooringsweredescribedwhichconsistoftemperaturesensors,conductivity-temperaturesensors,andpressuresensors.Theseinstrumentsaredeployedinshallow,low-sedimentation,protectedwatersnearthefjordwallsandenableawaytorecordsurfacewaterpropertiesinicebergfjords.

Cost:<$10kestimated

AlsopresentedwastheutilityofsmallGPSdevicesforicebergtracking,whichcanbeusedtoconstraincirculationintheupperwatercolumn.Theseareinexpensiveinstrumentsbutexpensivetodeployandlimitedtofjord-scalespeedsduetotheirlowprecision,socannotbeusedforverticalmotion.

Cost:$200

FiammaStraneo(WHOI,USA;SEARCH):PIESandITPs

Aninstrumentthatusesacousticstoderiveadepth-integratedtemperatureofthewatercolumn

47

wasdescribed.ThePressureInvertedEchoSounder(PIES)instrumentsarebottomanchored,easytodeployandlast4-5years,butmustberetrievedfordatarecovery.Itwasnotedthatthereremainissueswithsedimentaccumulationinglacialfjordswithregardstoasolidsubstratefordeployment.

Cost:$35k(+$7ktoaddaCT)

AlsopresentedwereIce-TetheredProfilers(ITPs),satellitetelemeteredmooredCTDprofilersthataredeployedthroughice.ITPsarearobustandtestedtechnologyintheArcticandareproposedasinstrumentsthatcouldbedeployedthroughglaciertonguesorfasticetoprovidetemperature,salinity,velocityandopticalpropertiesfrom10-700mdepthintheicecavity.Theyhaveanominal2-yearlifetimeandthedataistelemetereddaily,eliminatingthelossofdataineventofinstrumentloss.

Cost:$150k

JohnMortensen(GINR,Greenland):HydrographicTransectsinGodthabsfjord

MonthlyhydrographicsectionsfromsmallsurfacevesselsweredescribedforthewatersaroundNuuk,Greenland.Themethodrequirespersonnelonsiteyear-round.OpenwaterconditionsandfewicebergsproviderelativelyeasyaccesstoGodthabsfjordandallowstreamlinedmooringthatcanextendtothesurface.

Cost:$10k/day

ChristianRodehacke(DMI,Denmark):OceanographicExpeditionsinNWGreenland

AseriesofhydrographicprofilescollectednearQaanaaqFjord,NWGreenland,inlatewinter(March/April)since2011weredescribed,aswellassectionsacrossNaresStraitin2015.FutureplansforCTDprofilinginAugust/September2016-17wererelatedbutaredependentonsupportfromDanishArcticCommand,whichhasnotyetbeenapproved.InstallationofmooringsthroughseaicewithanautomatedweatherstationnearQaanaaqwasdescribed.

Costs:unknown

AqqaluRosing-Asvid(GINR,Greenland):Satellite-linkedDataLoggersonSeals

Amethodforobtainingoceantemperatureandsalinityprofilesfromsealstaggedwithsmallexpendabledataloggerswaspresented.Theinstrumentsaresatellitetelemeteredandsenddatadailyovertheaverage10-monthspanofthetag(July-May,betweensealmoltingeachspring).Sealsgenerallydive4-12timesperdaytodepthsofseveralhundredmeters(upto600m),withrangesvaryingfromasinglefjordtohundredsofkilometers,speciesdependent.Theloggerssampleat1Hzduringdeepdives,andalthoughtheaccuracyandresolutionofthesensorsissomewhatpoorerthantraditionaloceanographicinstrumentstheyprovideameanstocollectqualitywatercolumnprofilesfromotherwiseinaccessibleregions.Thefeasibilityofcapturingandtaggingsealswas

48

discussedandarecommendationwasgiventostartwithsmallpilotprograminanewfjordtodeterminebehaviorofseals.PlanswerediscussedtotagGreenlandichalibutthatsamplethedeepbenthicwaters,althoughthe5-10%recaptureratereducesdatareturn.Someconcernswereraisedaboutbiasedsamplingusingtaggedmarinecreaturesandtheinherentlyunpredictablenatureofnature.

Cost:$8k/tag+sealtaggingcosts(minimum$8k-16ktotag3sealseachyear)

49

Summary discussion, led by Bob Bindschadler

Note takers: Timothy Bartholomaus & Rebecca Jackson

What are the key variables to be measured at GrIOOS sites?

1. Ocean, presented by Dave Sutherland.

• Essential measurements: temperature, salinity, pressure in fjord; winds in fjord; moorings on shelf (maybe desirable?); bathymetry.

• Desirable measurements: water properties on shelf (maybe essential); Pressure Inverted Echo Sounder (PIES) for heat content; velocity; turbidity; biological measurements.

• Essential instruments: moorings (through ice for floating tongues), Automatic Weather Station (AWS) near the fjord surface and within fjord walls, PRES for floating tongues.

• Desirable instruments: seals. • Open questions that were discussed but not resolved: How much structure in depth should the

moorings have? What sort of redundancy? Are seals biased samplers? How important is it to have moorings on the shelf? This might be especially important for shallow-silled fjords.

2. Glaciology, presented by Twila Moon.

• Essential measurements: discharge runoff, ice velocity, ice elevation, surface mass balance, melange, calving, terminus position

• Essential instruments (“F” indicates needed for floating termini, “G” indicates needed for grounded or near-grounded termini, $ are price per unit) : cameras (15 min repeat interval) with infrared capability (G, $2-10k), Automatic Weather Stations (Potentially three: on the ice ~1000 m, at the terminus, and at the fjord mouth) F/G ($20k), seismic (1-3) for calving and subglacial discharge F/G ($40k), Terrestrial Laser Scanner (TLS, G $450k), GPS (Floating $5k), Phase-sensitive radio echo sounding (pRES) (Floating, $10k).

• Essential to support: satellite observations of ice surface elevation and ice speeds.

3. Discussion points.

What are the timescales at which we need these observations? The ocean and glacier observations should be synced for optimal monitoring.

What should be the spatial focus of these observations? How much of the glacier and fjord should be monitored? For example, do cameras need to cover the whole melange and fjord, or just focus on the terminus?

There was debate over how important it is to instrument the shelf. Mark Inall argued that monitoring the Atlantic waters on the shelf is a crucial component for this overall effort.

This led into a discussion of various larger-scale oceanic monitoring efforts at Denmark Strait, Davis Strait and Fram Strait. It was agreed that GrIOOS should attempt to leverage the ongoing work surveying the fluxes through these straights.

50

Choosing GrIOOS sites

The discussion of site selection was guided by a vote, where all workshop participants cast three votes for their preferred sites around Greenland. The top three winners were Helheim, Jakobshavn and 79N. The runners up were, in order, Petermann, Rink, Kangerdlugssuaq Glacier, Upernavik, Qanaaq, KNS. The pros and cons of each site were discussed and summarized here.

• Helheim. Pros: representative of southeast Greenland, easy access, stabilizing geometry, experience at site and relatively extensive existing record. Cons: complex geometry on shelf and in fjord, large melange.

• Jakobshavn. Pros: most potential for retreat and contribution to SLR, easy access to ice, simple geometry, good long-term history. Cons: no high topography that provides an elevated view of the terminus, sill that limits Atlantic water, large and atypical melange, inaccessible by boat.

• 79N. Pros: science community expects large changes, an ice stream, existing observations (though limited), close to Fram St array, floating tongue which can be used as a platform, an upstream ice core. Cons: remote, complex geometry, difficult logistics, accessibility and lack of community engagement, unusual geology.

• Petermann: existing data and ongoing work, easier to access than 79N (debated), simple geometry, long-term record from paleo studies, ice shelf as platform, good cliff viewing geometry for cameras. Cons: similar to 79N (debated), hard to access, small SLR contributor, Naires St. moorings are gone, atypical of Greenland.

• Other sites. KNS has good ocean measurements but needs ice. Qanaaq also has ongoing measurements from Japanese and a well connected local community. Rink has extensive existing measurements and is currently stable, but is poised for retreat.

There was some confusion and debate about whether it is a pro or con for a site to already have ongoing funding when considering GrIOOS site selection.

Discussion of how to proceed

How much is GrIOOS steering people towards certain sites versus just a framework for getting measurements at sites? Should there be a menu of sites that countries can choose from? Is GrIOOS an umbrella that groups can work under, or is it really trying to emphasize key sites? This point is unclear.

There is a tradeoff between number of sites and the extent of observations at each site. Ute suggests that it is better to have a larger list of candidate glaciers and include smaller glaciers.

How will this be funded? No one country is going to fund the whole thing. Being part of GrIOOS should increase one’s chances of getting funded. The NSF Arctic Observing Network provides an opportunity to begin funding in the USA.

What are the key components of an observing system? There was a discussion of governance and data sharing. Minimum requirements for an observing network include a framework for: 1. key variables to be measured, 2. data quality policies and 3. data sharing policies. Several different possible frameworks were discussed. AON requires data to be immediately available. PROMICE demonstrates that this is important, valued and successful. Quick and centralized access to data is key, though there should be flexibility so

51

that countries are not excluded from the GrIOOS process for embargo reasons. It was also pointed out that it might not be worthwhile to be rigid about rules before there is even any funding.

Bob suggests that the group should read the Framework for Ocean Observing (FOO) as a guide. A workshop report will be written, though it is not yet clear where it should be published. Presentations from workshop will be available on the GRISO website.