ECCO and associated projects :: Arctic System Model interests

1. ECCO and associated projects :: Arctic System Model interests Chris Hill, cnh@mit.edu. Boulder, May 2008.

2. Who and what is ECCO • ECCO (Estimating the Circulation and Climate of the Ocean)  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 http://ecco2.org http://www.ecco-group.org Participants – MIT, Harvard, NASAs (JPL, GSFC, Ames), Princeton, AWI, U. Hamburg, Scripps, AER.

3. ECCO overview Ocean and sea-ice models e.g Gulf Stream transport e.g ACC transport Dynamically consistent estimates Optimization Remote and in-situ obs

4. Technical information - I • 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 • Multiple 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.

5. Technical information - II Optimization approaches Adjoint based Heimbach et. al. FGCS 2005. Green functions (perturbation) based Together  Lots of sensitivity information/maps as well as state estimates.

6. 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.

7. ECCO products e.g. Dynamically consistent ice and ocean flow estimates Michel Schodlock Menemenlis, Zhang, Hill ACC transport Global state estimate 92-06 for 18km cube sphere grid.

8. ECCO products e.g. Estimated sensitivity of ice export through Fram Strait (FS) to previous years ice-thicknesses. Patrick Heimbach 4 years earlier 1 year earlier

9. 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.

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

11. Current Arctic ECCO solution.

12. - 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

13. People (in no particular order!) Patrick Heimbach - MIT An Ngyuen - JPL Ron Kwok - JPL Michael Schodlok - JPL Alan Condron - WHOI Peter Winsor - WHOI Dimitris Menemenlis - JPL Jean-Michel Campin - MIT John Marshall - MIT Stephanie Dutkiewicz - MIT Mick Follows - MIT Carl Wunsch – MIT Matt Mazloff - MIT Ian Fenty - MIT Martin Losch - AWI Manfredi Manizza - MIT Oliver Jahn – MIT Jinlun Zhang – UW more always welcome!