ICEBellIce Mass Balance in the Bellingshausen Sea

James Clark Ross, Nov 2010

Participants

BAS (Maksym), SAMS (Wilkinson)

WHOI, DTU, U Manitoba,UTSA

Partners

UCL, DAMTP, UCSC

ICEBellSnow and ice processes, mass balance, and air-ice-ocean interactions in

the Bellingshausen Sea

ICEBell

Rothera

Primary Objectives

•Snow and sea ice thickness distribution•Cryosat/ICESat algorithms•Snow and ice melt processes•Satellite snow depth

ICEBell Programme

•AUV-based 3D ice draft measurements•Airborne topographic mapping (ex Rothera)•In situ snow and ice thickness and properties

Nominal cruise track (ice condition dependent)Red boxes show primary areas of interest

Ice Concentration Trends

September Snow Depth

Why the Bellingshausen Sea?

• Ice extent has seen the largest declines in the Bellingshausen – declines in ice season length rival those for the Beaufort/Chukchi

• Subject to frequent extreme deformational events that impact ice thickness distribution

• Has some of the deepest snow cover in the Antarctic – important impacts on flooding and snow ice formation, summer melt processes, and interpretation of satellite altimetry data

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Ice Thickness Distribution

• No large-scale detailed measurements of snow and ice thickness distribution in Antarctic

• Currently, large discrepancy between in-situ and satellite altimeter estimates

• Ice thickness determined primarily from ship-based visual observations

– Biased to thin ice areas

– Does not adequately account for ridging

• Satellite estimates complicated by deep snow cover

– large uncertainty in satellite snow depths

• Relationship between snow distribution and ice thickness distribution not well known

ICEBell

Rothera

Primary Objectives

•Snow and sea ice thickness distribution•Cryosat/ICESat algorithms•Snow and ice melt processes•Satellite snow depth•Ice-upper ocean interactions

ICEBell Programme

•AUV-based 3D ice draft measurements•Airborne topographic mapping (ex Rothera)•In situ snow and ice thickness and properties

Nominal cruise track (ice condition dependent)Red boxes show primary areas of interest

2002 2003 2004 2005

2006 2007 2008 2009

Nov 5 Ice Conditions

Large interannual variability so exact cruise track will be contingentConditions as of 23/09/10 are similar to 2007 conditions

WHOI SEABed AUV(Hanu Singh)

• Floe scale survey (500 x 500 m) ~ 4 hours

• 230 kHz multibeam sonar• CTD + ADCP• Microstructure probe• 7-band optical radiometer

Open Water

Complex ridge system

Example of ice bottom topography from an AUV multibeam survey

Courtesy J. Wilkinson

BAS MASIN twin-otter will overfly sampling sites providing detailed surface topography of ice floesThis may occur prior, during or after occupation

Riegl Q140/240 scanning lidarHoneywell GPS/INSGPS rcvrs (Javad, Trimble, Ashtech)

Provides sea-ice freeboard swaths => Thickness + detailed mapping of ridges and leads

Images Courtesy of Rene Forsberg

DTU-space Airborne Lidar (BAS/DTU)

Surface Characterisation(U of M, BAS, SAMS, UTSA, DRI)

• Terrestrial 3D laser mapping of snow surface

• EM-31 surveys and conventional drilling

• Snow depth distribution, properties and flooding extent (GPR)

• Ice structure, properties, biology (coring)

SAMS Ice Mass Balance Buoys• Monitor surface and basal

melt• Several spar freeze-in buoys

• Provide beacons for Twin over-flights

• Some will form arrays for deformation information

Air-ice-ocean interactions

• Airborne boundary layer flux measurements from Twin-Otter. (BAS)

• Oceanographic observations (CTD) (SAMS/BAS)

• Microstructure under melting sea ice (SAMS)

Locations of CTD stations occupied in 2007Blue line is a possible cruise track for JR240

NASA IceBridge flight in support of ICEBellLikely date ~22 Oct

Flight above is for a “light” ice year. 2010 is likely to be light to moderate. In this case, we will operate more to the west of Alexander Island than to the North

Cruise area of interest

Precise cruise track will depend on ice conditions and success of Twin overflights. The primary criteria are 1) successful completion of surveys and overflights over a range of ice types2) Penetration into the main ice pack (past the broken ice of the marginal ice zone)

Polarview• Near daily imagery for aiding navigation

in ice and cruise track planning • High resolution radar imagery from

Envisat and Radarsat-2 (25-100 m resolution)

Example subscene of western edge of Charcot Island

~30km x 60 km