Overall, the spectral models, especially those of lower resolution, perform less well than the grid point models. There is less evidence of a dependence of quality on resolution for grid point models, with the 4 by 5 GLAS 1980 model probably the best. The contour interval is 1 mm d -1 except in congested regions. The contour interval is 1 mm d -1 . The contour interval is 1 mm d1 except in congested regions.
Space precludes more than a brief statement of the more important needs.
Hydrology Research is needed to overcome the fundamental parametrization problems of transfer of theory and models based on microscale observations to the GCM grid scale, allowing for inhomogeneities of soils, slopes, vegetation, precipitation, etc. Roughness Assessments of GCM formulations in relation to the surface stress are desirable in view of the large sensitivity to its formulation found in the GISS model by Hansen et al. The simulation of cloudiness in GCMs is generally poor.