Microwave Attenuation Statistics Estimated from Rainfall and Water Vapor Statistics

Annual distribution curves are obtained for values of total atmospheric attenuation over a 50-km path and a 1-km path at Washington, D.C. These results are obtained by analyzing the available meteorological data, though these are usually ill-suited to the purpose; theoretical coefficients are used for converting into radio attenuation values. The problem of obtaining rainfall rates on the longer path is solved empirically using data from a network of rain gauges; these data, together with additional inference, indicate that annual statistics for hourly point depths may be interpreted as equivalent to instantaneous rates on a path about 50 km long. Extensions of the results to other portions of the country are discussed.