North Atlantic Climatological heat/freshwater fluxes 3-day average NCEP winds

John [email protected]

US East Coast ROMS/TOMS ProjectsUS East Coast ROMS/TOMS Projects

North Atlantic Basin (NATL) North Atlantic Basin (NATL) Northeast North American shelf (NENA)Northeast North American shelf (NENA)

NSF CoOP Buoyancy driven flow (LaTTE)NSF CoOP Buoyancy driven flow (LaTTE)CBLAST-LowCBLAST-Low

Northeast Observing System (NEOS)Northeast Observing System (NEOS)

John WilkinJohn Wilkin H. Arango, K. Fennel, L. Lanerolle, J. LevinH. Arango, K. Fennel, L. Lanerolle, J. Levin

Institute of Marine and Coastal SciencesInstitute of Marine and Coastal SciencesRutgers University Rutgers University


North AtlanticNorth Atlantic

Climatological Climatological heat/freshwater fluxesheat/freshwater fluxes

3-day average NCEP 3-day average NCEP windswinds


Northeast North Atlantic (NENA) embedded within NATLNortheast North Atlantic (NENA) embedded within NATL

3-day average open boundary values from NATL3-day average open boundary values from NATL7-component NPZD ecosystem7-component NPZD ecosystem

TemperaturTemperaturee

ChlorophyllChlorophyll


Lagrangian Transport and Lagrangian Transport and Transformation Experiment (LaTTE)Transformation Experiment (LaTTE)

• Dye release in Hudson River plumeDye release in Hudson River plume

• 4D-var assimilation with ROMS4D-var assimilation with ROMS

• Coupled bio-optical modeling with EcoSimCoupled bio-optical modeling with EcoSim


• Precise observations of air-sea fluxes and turbulent mixing from Precise observations of air-sea fluxes and turbulent mixing from CBLAST are ideal for evaluating the suite of ocean model vertical CBLAST are ideal for evaluating the suite of ocean model vertical turbulence closure schemes implemented in ROMS.turbulence closure schemes implemented in ROMS.

• This comparison will be possible provided the model captures the This comparison will be possible provided the model captures the essential features of the ocean heat budget on diurnal to several essential features of the ocean heat budget on diurnal to several day time-scales, and spatial scales of order 1 km.day time-scales, and spatial scales of order 1 km.

• Modeling complements the interpretation of the field observations Modeling complements the interpretation of the field observations by quantifying unobserved lateral transport and mixing of heat.by quantifying unobserved lateral transport and mixing of heat.

CBLAST: CBLAST: Coupled Boundary Layers and Air-Sea TransferCoupled Boundary Layers and Air-Sea Transfer

The ONR CBLAST-Low program focuses on air-sea interaction and The ONR CBLAST-Low program focuses on air-sea interaction and coupled atmosphere/ocean boundary layer dynamics at low wind coupled atmosphere/ocean boundary layer dynamics at low wind

speeds where processes are strongly modulated by thermal forcing.speeds where processes are strongly modulated by thermal forcing.


MVCOMVCO

Nantucket SODARNantucket SODARK

ASITASIT

ASIMET moorings with ASIMET moorings with ocean T(z) and ADCPocean T(z) and ADCP

RemoteRemoteSensingSensing

AircraftAircraft

3-D3-DMoorinMoorin

gg

CBLAST-Low Observing System:CBLAST-Low Observing System:


Irradiance

Irradiance

23m

15m

U, T, QU, T, Q Heat, mass & Heat, mass &

mom. flux, mom. flux, εεWavesWaves

WavesWaves T, ST, S

Heat, mass Heat, mass mom. flux, mom. flux, εε

Solar, IR, rain, Solar, IR, rain, U, T, QU, T, Q Heat, mass & Heat, mass & momentum flux, momentum flux, εε


1 km horizontal resolution1 km horizontal resolution20 s-levels (stretched toward surface)20 s-levels (stretched toward surface)

ROMS CBLAST configurationROMS CBLAST configuration

Open boundary conditions:Open boundary conditions:

Inflow climatology [7] + outflow Inflow climatology [7] + outflow radiation [8] on T,S, u, vradiation [8] on T,S, u, vClimatology, tides [9], radiation (Climatology, tides [9], radiation (gh) gh) on on and depth average u,v and depth average u,v

160 x 380 x 20 grid requires approximately 160 x 380 x 20 grid requires approximately 2 CPU mins per model day on 16-2 CPU mins per model day on 16-processor HP/Compaqprocessor HP/Compaq

M2 displacement ellipses from ADCIRC

COAMPS CBLAST, 3km, 91x91

9 km

27 km, 151x121x30

Surface forcing:Surface forcing:

Heat and momentum fluxes from bulk Heat and momentum fluxes from bulk formulae [6] with model SST, observed formulae [6] with model SST, observed downward long-wave at MVCO, and downward long-wave at MVCO, and TTairair, p, pairair, rel. humidity, , rel. humidity, UU1010, , VV1010, and , and

short-wave radiation from 3 km short-wave radiation from 3 km resolution nested COAMPS 6--36 hr resolution nested COAMPS 6--36 hr forecastforecast


Circulation around the Circulation around the Nantucket Shoals is augmented Nantucket Shoals is augmented by strong tidal rectified cyclonic by strong tidal rectified cyclonic flow that carries water flow that carries water northward into Vineyard Sound northward into Vineyard Sound through Muskegat Channel through Muskegat Channel (between Nantucket and the (between Nantucket and the Vineyard). Vineyard).

Mean circulation and heat budgetMean circulation and heat budget

The open boundary climatology imposes a The open boundary climatology imposes a south and westward flow from the Gulf of south and westward flow from the Gulf of Maine, through Great South Channel and Maine, through Great South Channel and around Nantucket Shoals.around Nantucket Shoals.

Southwest of Martha’s Vineyard, and within Southwest of Martha’s Vineyard, and within Vineyard Sound, winds drive eastward depth Vineyard Sound, winds drive eastward depth averaged flow.averaged flow.

July 2002 mean



Tidal mixing generates a region of perpetually cold SST on the eastern flank of the Nantucket Shoals

3-day composite SST for 30-Aug-2002


Air-sea flux (QAir-sea flux (Qnetnet) is greatest east of Vineyard Sound where SST is ) is greatest east of Vineyard Sound where SST is

cold, but is largely balanced by divergence due to tidal mixing. cold, but is largely balanced by divergence due to tidal mixing.

Ocean temperature increase (storage) is largest south of The Islands, Ocean temperature increase (storage) is largest south of The Islands, primarily due to surface heating. primarily due to surface heating.

Horizontal divergence is small in the region of the Horizontal divergence is small in the region of the B-CB-C ASIMET ASIMET moorings - indicating a region of approximate 1-D vertical heat balance moorings - indicating a region of approximate 1-D vertical heat balance suited to evaluating ROMS vertical turbulence closures. suited to evaluating ROMS vertical turbulence closures.

July 2002


MVCO

The time mean advection The time mean advection cools the box at, on cools the box at, on average, 200 W/maverage, 200 W/m22. The . The net “eddy” divergence net “eddy” divergence ((u’T’u’T’) warms the MVCO ) warms the MVCO region at about 50 W/mregion at about 50 W/m22. .

Episodic positive Episodic positive divergence (cooling) divergence (cooling) events briefly arrest the events briefly arrest the warming trend. warming trend.

Time series of the heat budget in a box near Time series of the heat budget in a box near MVCO shows half the air-sea flux goes to MVCO shows half the air-sea flux goes to warming the water column, and half is warming the water column, and half is removed by lateral divergence. removed by lateral divergence.


CTD temperature section between ASIT and mooring-A, late July 2001.

Observed Modeled

Qualitative comparison to subsurface validation data (below) shows realistic Qualitative comparison to subsurface validation data (below) shows realistic vertical stratification and mixed layer depths. In 2003, an array of 5 subsurface vertical stratification and mixed layer depths. In 2003, an array of 5 subsurface moorings between ASIT and ASIMET mooring-moorings between ASIT and ASIMET mooring-AA will enable validation of the will enable validation of the modeled evolution of the diurnal mixed layer. modeled evolution of the diurnal mixed layer.


COAMPS 72-hour forecast is generated every 12 COAMPS 72-hour forecast is generated every 12 hours at ARL.HPC.mil and transferred to IMCS hours at ARL.HPC.mil and transferred to IMCS where ROMS runs for the same forecast cycle.where ROMS runs for the same forecast cycle.

Real-time validation is available using CODAR Real-time validation is available using CODAR on Nantucket (operational after July 7, 2003).on Nantucket (operational after July 7, 2003).

ROMS forecasts will be factored into the ROMS forecasts will be factored into the deployment strategy for drifting instrument strings deployment strategy for drifting instrument strings providing Lagrangian observations of evolving providing Lagrangian observations of evolving mixed-layer.mixed-layer.

Operational forecasts began July 8, 2003Operational forecasts began July 8, 2003


CBLAST: CBLAST: Lessons for ocean modeling:Lessons for ocean modeling:

• With sufficient realism in the model bathymetry and forcing, model With sufficient realism in the model bathymetry and forcing, model vertical turbulence parameterizations can be critically evaluated by vertical turbulence parameterizations can be critically evaluated by comparison to CBLAST observations comparison to CBLAST observations

• CBLAST observations ideal for evaluating turbulence closureCBLAST observations ideal for evaluating turbulence closure

– combination of direct air-sea flux observations, and in situ oceanic combination of direct air-sea flux observations, and in situ oceanic profile observationsprofile observations

• Need to consider spatially variable atmospheric forcing (COAMPS)Need to consider spatially variable atmospheric forcing (COAMPS)

• Initial conditions are a source of uncertainty in the model configurationInitial conditions are a source of uncertainty in the model configuration

• A 1-D heat balance occurs near the B-A-C ASIMET mooring sites, A 1-D heat balance occurs near the B-A-C ASIMET mooring sites, and these data will be used for evaluation of model turbulent closures. and these data will be used for evaluation of model turbulent closures.


Lessons for data analysis:Lessons for data analysis:

• Model shows remote mixing and advection significantly influence the local Model shows remote mixing and advection significantly influence the local heat budget at the SECNAV mooring site and CLAST tower heat budget at the SECNAV mooring site and CLAST tower

• Tides significantly affect the mean circulation and heat budget. Lateral Tides significantly affect the mean circulation and heat budget. Lateral heat transport is large in much of the region, including near MVCO, and heat transport is large in much of the region, including near MVCO, and will need to be considered in the analysis of ASIT heat budgets. will need to be considered in the analysis of ASIT heat budgets.

• Wind-driven upwelling circulation contributes to the heat budget Wind-driven upwelling circulation contributes to the heat budget southwest of Martha’s Vineyard.southwest of Martha’s Vineyard.

• Wind-driven upwelling contribution remains unquantified at this stage but Wind-driven upwelling contribution remains unquantified at this stage but is likely important in regionsis likely important in regions







• assimilate regional assimilate regional CODAR with 4D-VarCODAR with 4D-Var

• use tangent linear use tangent linear and adjoint to develop and adjoint to develop AUV deployment AUV deployment stategiesstategies

• apply multiple-scale apply multiple-scale nesting in support of nesting in support of subregion studies subregion studies (LaTTE, CBLAST …)(LaTTE, CBLAST …)


• Hierarchy of modeling studies from basin to coastal using Hierarchy of modeling studies from basin to coastal using ROMS/TOMS tools ROMS/TOMS tools

• Processes: COProcesses: CO22 cycling, buoyancy-driven flow, wind-driven cycling, buoyancy-driven flow, wind-driven

upwelling, air-sea interaction, coastal bio-optics and sediment upwelling, air-sea interaction, coastal bio-optics and sediment transport transport

• Integrated observational/modeling studiesIntegrated observational/modeling studies

• CBLAST: air-sea interaction, waves, mixingCBLAST: air-sea interaction, waves, mixing

• LaTTE: intensive observing systemsLaTTE: intensive observing systems

• NEOS: prototype modern, relocatable, observing networkNEOS: prototype modern, relocatable, observing network

• Adjoint, tangent linear codes feature in most projectsAdjoint, tangent linear codes feature in most projects

• Developing coastal prediction systemsDeveloping coastal prediction systems

• using new observing system capabilities, adaptive sampling using new observing system capabilities, adaptive sampling design, 4D-Vardesign, 4D-Var

SummarySummary

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North Atlantic Climatological heat/freshwater fluxes 3-day average NCEP winds