Overview of the SHEBA Project (INVITED)

The Surface Heat Budget of the Arctic Ocean (SHEBA) project has two goals: (1) To demonstrably improve the simulation of present-day arctic climate, including its variability, by global climate models (GCM's); and (2) To enhance the interpretation of remote sensing data for monitoring the arctic climate system. To reach these goals, SHEBA was planned as a three-phase project. Phase I (1995-96) involved modeling, data analysis and instrument development in preparation for the SHEBA field experiment. Phase II (1997-99) involved a year-long field experiment at a drifting station on the multiyear pack ice of the Arctic Ocean, together with initial analysis of the resulting ocean-atmosphere-ice data set. Phase III (2000-2002), involves the application of this data set to development and implementation of improved climate models and remote sensing interpretation techniques. The experimental design for SHEBA focuses on processes that affect the ice-albedo and cloud-radiation climate feedback mechanisms. The main framework for analysis and modeling is the single column model (SCM), representing the upper ocean, sea ice and atmosphere at a single horizontal grid point in a GCM.

In this overview, we describe how the SHEBA data set matches up with the requirements of SCM's for initial values, forcing functions and verification data. Drawing on both published SHEBA results and our own analyses of the SHEBA data set, we present estimates of the annual energy and water budgets of the SHEBA column including the surface heat budget, together with error bars that quantify the uncertainty in the estimates. Using a single column version of the Community Climate System Model (CCSM) we analyze selected periods to illustrate the processes that affect the ice-albedo and cloud-radiation climate feedback mechanisms. We indicate some of the directions of current SHEBA research and, in the light of Phase III, what additional measurements should be made in future field experiments concerned with these topics.