Surface Energy Balance and Turbulence Characteristics Observed at the SHEBA Ice Camp During FIRE III

Abstract

The Institute for Marine and Atmospheric Research Utrecht (IMAU) participated in the FIRE III (First ISCCP Regional Experiment, ISCCP International Satellite Cloud Climatology Project) experiment in May 1998. In this paper we describe surface layer measurements performed on the sea ice at the SHEBA (Surface Heat and Energy Balance of the Arctic ocean) camp and compare these with measurements collected above a grasscovered surface in Cabauw, the Netherlands. The observations consist of both highfrequency turbulence measurements and mean-profile measurements of wind, temperature and humidity. In addition, we measured the upward and downward components of both the longwave and shortwave radiation, and the snow and ice temperatures in the upper 40 cm. The observations give a detailed picture of all components of the energy balance of the Arctic sea-ice surface. The turbulence measurements are used to study the surface layer scaling of the turbulence variables in the stable boundary layer. More specifically, we showed that the integral length scale of the vertical velocity fluctuations serves as the relevant turbulence length scale. The monthly-averaged energy balance of the Arctic sea-ice was dominated by radiative fluxes, whereas, the sensible and latent heat flux and the energy flux into the surface were rather small. A detailed inspection of the diurnal variations in the turbulent fluxes however indicates that although the monthly-averaged values are small, the hourlyaveraged values for these fluxes are significant in the surface energy balance.