PILPS - Phase 2(e) -

Arctic Model Intercomparison

***Forcings for Stage 1 of PILPS 2e are now available! See "Stage 1 Instructions" for details.***

Climate modeling studies indicate that global warming may be larger at high latitudes than elsewhere primarily due to reduced albedo associated with contraction of sea ice extent and seasonal snow cover. The strength of the coupling between the ocean, land, and atmosphere in the Arctic is particularly important because of its influence on the net transfer of heat northward, and fresh water southward, which in turn affects global climate and weather.

These considerations motivate the improvement of high-latitude land surface representations within coupled land-atmosphere models used for numerical weather and climate prediction. PILPS Phase 2(e) will carry on in the tradition of Phases 2(c) and 2(d) by conducting a multi-year, spatial intercomparison of hydrology and land surface transfer schemes in northern regions. The project will be a joint activity of GEWEX, (through PILPS), and the Arctic Climate System Study (ACSYS).

The purpose of PILPS 2(e) is "To evaluate the performance of land surface parameterizations in high latitudes, in a context that allows evaluation of their ability to capture key processes spatially. These include snow accumulation and ablation, soil freeze/thaw and permafrost, and the existence of large seasonally frozen lakes and wetlands."

A preliminary science plan for the intercomparison was formulated in March 1999 by a small working group formed jointly by ACSYS and GEWEX. The intercomparison will consist of three stages. Stage 1 will utilize data from the Torne River basin in Sweden. Phases 2 and 3, planning for which will depend on the outcome of Stage 1, would tentatively utilize data from GEWEX Continental Scale Experiments in the Mackenzie River basin (MAGS) and the Lena River basin (GAME-Siberia).