How useful are upper level specific humidity fields on sigma surfaces?
[11/15/97] The higher levels in this stack do not contain sufficient precision for many applications. For levels above the 0.1682 sigma level, the fields may contain only constant zero values. • How does reanalysis handle snow cover?[11/14/97] The snow coverage was estimated from satellite imagery (once per week) and snow coverage was converted into a snow depth by assuming it is a simple function of the surface temperature. (Yes, it is unrealistic but we have no snow depth observations.) For the purposes of data assimilation, the snow depth is not critical. Radiative properties depend on the coverage rather than depth. In addition, if the snow coverage happened to melt away (because the snow wasn’t deep enough), the snow coverage gets reinitialized with “observations” every six hours. It is suggested that snow coverage be used rather than the snow depth; i.e., convert the snow depth (WEASD) into 1’s or 0’s. The skin temperature over a snow surface is determined by a balance of the flu
