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