PNNL

Abstract

Clouds exert a significant influence on the climate of the Arctic through radiative energy transfer. At the same time, the distribution of clouds and the processes that control it are not well understood. Clouds modify the energy reaching the surface, some of which returns to the atmosphere through turbulent transfer. The surface heat flux in turn influences boundary layer depths and temperatures and will have a corresponding influence on radiatively important liquid water paths and drop size distributions. Part of understanding this feedback is understanding how the distribution of surface heat fluxes affects boundary layer clouds. It is also important to determine how well large-scale models represent the surface heat fluxes, especially during periods like the spring melt when surface characteristics are rapidly changing. In this paper we compare measurements of surface sensible heat flux measured near Barrow and Atqasuk, Alaska during the spring melt of 2000. In addition, we compare these heat fluxes with those computed by the European Center for Medium-range Weather Forecast (ECMWF) model.