Arctic ice-ocean simulation with optimized model parameters: Approach and assessment

Abstract

We present an optimized 1992-2008 coupled ice-ocean simulation of the Arctic Ocean. A Green's function approach adjusts a set of parameters for best model-data agreement. Overall, model-data differences are reduced by 45%. The optimized simulation reproduces the negative trends in ice extent in the satellite records. Volume and thickness distributions are comparable to those from the Ice, Cloud, and land Elevation Satellite (2003-2008). The upper cold halocline is consistent with observations in the western Arctic. The freshwater budget of the Arctic Ocean and volume/heat transports of Pacific and Atlantic waters across major passages are comparable with observation-based estimates. We note that the optimized parameters depend on the selected atmospheric forcing. The use of the 25 year Japanese reanalysis results in sea ice albedos that are consistent with field observations. Simulated Pacific Water enters the Bering Strait and flows off the Chukchi Shelf along four distinct channels. This water takes ∼5-10 years to exit the Arctic Ocean at the Canadian Arctic Archipelago, Nares, or Fram straits. Atlantic Water entering the Fram Strait flows eastward, merges with the St Ana Trough inflow, and splits into two branches at the southwest corner of the Makarov Basin. One branch flows along Lomonosov Ridge back to Fram Strait. The other enters the western Arctic, circulates cyclonically below the halocline, and exits mainly through the Nares and Fram straits. This work utilizes the record of available observations to obtain an Arctic Ocean simulation that is in agreement with observations both within and beyond the optimization period and that can be used for tracer and process studies. Copyright 2011 by the American Geophysical Union.