Clapp, Philip F. (Philip Fanshawe)

Recent estimates of the brightness and albedo of the earth-atmosphere system, averaged for individual months from meteorological-satellite data, are used to test-and modify a formula for the short-wave radiation budget. The formula is used in a numerical model designed for long-range forecasting experiments. Whereas previously the model formula assumed that the average transmissivity of the clouds is a slowly-varying function of latitude alone, the tests discussed here show that there is a linear-inverse relation between cloudiness and transmissivity. This is due mainly to a strong tendency for the average thickness of the different cloud types, as well as for the relative frequency of the more vertically-developed types, to increase as the monthly-mean cloudiness increases. This modification has an important effect on the heat budget of the earth atmosphere system, and is easy to introduce into the model.

National Weather Service (NWS)

United States