Collaborative Research: Toward reanalysis of the Arctic Climate System - sea ice and ocean reconstruction with data assimilation

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PROJECT ABSTRACTTitle: Toward reanalysis of the Arctic Climate System - sea ice and ocean reconstruction with data assimilationThe PI's propose to develop an integrated set of assimilation procedures for the arctic ice-ocean system that are able to provide gridded data sets that are physically consistent and constrained to the historical observations of sea ice and ocean parameters. Building on their past research activities in sea ice and ocean data assimilation, they propose to make some first steps toward the creation of an Arctic Climate System Reanalysis that uses modern four-dimensional variational data assimilation methods employing new data assimilation procedures to maximize the integration of model results with observations. They will focus their attention on three distinct periods, each representing a different state of the Arctic climate. The first period is 1972-1978 when the Arctic was relatively cold and there is a large quantity of hydrographic data available, the second is 1989-1996 when large changes begin in the Arctic Ocean circulation, in its hydrographic structure, and in sea ice conditions, and the third is 1997- present when substantial amounts of open water begin to appear in the late summer. Comparison will be made with new reanalysis products with fields obtained by AOMIP models to validate AOMIP model results. After obtaining the reconstructed solutions with the best fit to the observations, they will focus on the analysis of the sea ice, water circulation, and ocean hydrography during these periods.Intellectual Merit: Understanding of the Arctic system and its change is an important goal of the SEARCH program. Accurate gridded atmospheric, cryospheric and oceanic fields consistent with and constrained by point observations are important to understanding the origin of past Arctic changes and are essential for forming accurate budgets of climate variables such as heat and freshwater fluxes. Practical implementation of data assimilation methods is necessary to properly understand and model the climate system, and this project will provide the most accurate results possible with modern techniques. These new simulations will help answer a variety of scientific questions of the SEARCH, SBI, and FWI projects and will significantly contribute to national and international components of ASOF and CLIVAR dealing with climate studies. The algorithms tested and validated in this project could also be applied to a reanalysis of the Arctic Ocean during the 2007-2009 IPY and will be used in existing and planned activities of SEARCH, DAMOCLES, COME, CAME and others.Broader Impact: Data will be available through a web site that will include links to other relevant projects and data, and will be designed to be useful for a variety of audiences including the scientific community, students, and the general public. Interpretations of the results will be published in scientific and popular journals. Educational activities within the project will include training of graduate and undergraduate students at USM and IARC, as well as integration of the material into courses taught at UW, USM and UAF. Active outreach to grade schools in the Fairbanks and Falmouth area and extensive participation in the Polar Science Weekend at the Pacific Science Center in Seattle will continue.