Surface fluxes

Surface fluxes are calculated separately for each land surface type (open water, ice, earth and land ice). For each type, a different high resolution PBL calculation is done to extrapolate the first layer atmospheric properites to the surface (defined as 10m above the ground). The diffusion parameters in the PBL layers are functions of the local turbulence closure scheme (Cheng et al, 2002) and are iterated to get a robust estimate of the surface properties (temperature, humidity, and tracer concentration) and fluxes. Generally, 2 or 4 surface flux time steps are done every hour, depending on the vertical resolution.