Chris Hill, cnh@mit.edu. Boulder, May 2008.

ECCO and associated projects :: Arctic System Model interests

Who and what is ECCO

http://www.ecco-group.orghttp://www.ecco-group.orghttp://ecco2.orghttp://ecco2.org

•ECCO (EEstimating the CCirculation and CClimate of the OOcean) ongoing data assimilation projects for fully global, full depth ocean monitoring, measuring and understanding. •strategy “formally” fit (least squares sense) dynamically consistent (i.e. no jumps) model solution to available obs. (satellite and in-situ) using some optimization system. • emphasis monitoring to improve understanding of changes in the ocean system on time-scales of decades and more. Arctic regions and sea-ice necessarily have an important role.

sites with detailed project information and results

Participants – MIT, Harvard, NASAs (JPL, GSFC, Ames), Princeton, AWI, U. Hamburg, Scripps, AER.

Ocean and sea-ice models

Optimization

Remote and in-situ obs

Dynamically consistent estimates

e.g Gulf Stream transporte.g ACC transport

ECCO overview

Data constraints include - sea level anomaly from altimeter data- time-mean sea level from Maximenko and Niiler (2005)- sea surface temperature from GHRSST-PP- temperature and salinity profiles from WOCE, TAO, ARGO, XBT, etc.- sea ice concentration from passive microwave data- sea ice motion from radiometers, QuikSCAT, and RGPS- sea ice thickness from ULS- marine mammal network- grace gravity field/geoid

Estimated control parameters include- initial temperature and salinity conditions- atmospheric surface boundary conditions- background vertical diffusivity- critical Richardson numbers for Large et al. (1994) KPP scheme- air-ocean, ice-ocean, air-ice drag coefficients- ice/ocean/snow albedo coefficients- bottom drag and vertical viscosity

Technical information - IMultiple Related Ocean and Sea-Ice MITgcm Configurations.

-Approx 1 degree production system 80oN/S.

-Approx 1/6 degree cube sphere production system, fully global.

-Regional cut-outs from above

-Under-development- approx 1 degree global.

Optimization approaches

Heimbach et. al. FGCS 2005.

Adjoint based

Green functions (perturbation) based

Together Lots of sensitivity information/maps as well as state estimates.

Technical information - II

Summary of key ECCO “products”1 – cost-function related data products

e.g. collections of “vetted” observations, with analysed estimates of the standard deviations/uncertainties.

2 – dynamically consistent estimates of time dependent, full ocean depth state of the ocean and sea-ice system for 1992 - ~present-day – see http://www.ecco-group.org/products.htm

3 – parallel ocean and sea-ice model configurations with adjoint capabilities. These are available with and without ESMF style component interfaces, at non-eddying and eddy permitting resolutions. Global and regional cut-out configurations are available – see http://mitgcm.org

4 – sensitivity study outputs and adjoint based tools for sensitivity analysis.

ECCO products e.g. Dynamically consistent ice and ocean flow estimates

ACC transport

Michel Schodlock

Global state estimate 92-06 for18km cube sphere grid.

Menemenlis, Zhang, Hill

ECCO products e.g. Estimated sensitivity of ice export through Fram Strait (FS) to previous years ice-thicknesses.

1 year earlier 4 years earlier

Patrick Heimbach

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ECCO product application example – Estimating biogeochemical properties of the Arctic basin.

Uses ECCO physical model, T, S, U, V, forcing and sea-ice. Embeds simplified MITgcm biogeochemical process model.

ECCO product application example – Examining impacts of “end-points” of NAO signal.

Current Arctic ECCO solution.

- Why an Arctic System Model is of interest

Technical - interchange and intercomparison of ideas and understanding, and …. - interchange and intercomparison of algorithmic implementations (apply new solvers, formulations etc…) - interchange and intercomparison boundary conditions - atmosphere, shelf/land-ice/meltwater (introduce new dynamic etc…) forum for suggesting observations and measurements (need more of these) robustness of ECCO analysis wrt to comparable calculations cost function development/uncertainities – how close to obs should models be improving overall Arctic solutions (and not degrade Antarctic etc… – ECCO solutions are global). Key application areas

Arctic sub-arctic/Atlantic/Pacific coupling. longer time-scale global ocean circulation impacts. Arctic ocean biogeochemical cycle(s). initial conditions for forecasting. modern era trajectory comparisons. limited area process model boundary conditions (**).

(**) examples of related MITgcm process work (relevant but not discussed)

"Circulation and water mass transformation in a model of the Chukchi Sea” Michael A. Spall Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA"

Riemenschneider U. and S. Legg, 2007. Regional Simulations of the Faroe Bank Channel Over ow in a Level Model, Ocean Modelling, 17, 93-122.

Haine, T. ., Earth & Planetary Sciences, Jo, Baltimore, USA, thomas.haine@jhu.edu HIGH-FREQUENCY FLUCTUATIONS IN DENMARK STRAIT OVERFLOW TRANSPORT

People (in no particular order!)

Patrick Heimbach - MITAn Ngyuen - JPLRon Kwok - JPLMichael Schodlok - JPLAlan Condron - WHOIPeter Winsor - WHOIDimitris Menemenlis - JPLJean-Michel Campin - MITJohn Marshall - MITStephanie Dutkiewicz - MITMick Follows - MITCarl Wunsch – MIT Matt Mazloff - MITIan Fenty - MITMartin Losch - AWIManfredi Manizza - MITOliver Jahn – MITJinlun Zhang – UW

more always welcome!