More On Rain Rate Distributions and Extreme Value Statistics

Reference 1 has described a methodology for calculating long-term distributions of high rain rates by applying the theory of extreme value statistics to the yearly maximum 5-minute rain rate data published by the National Climatic Center.2-3 The obtained high rain rate distributions cover the range of interest to the engineering of terrestrial microwave radio links. However, for other applications, such as earth-satellite radio engineering, the rain rate distributions in the moderate and low rain rate ranges are also needed. This paper describes a methodology to obtain rain rate distributions covering the entire range (i.e., from below 5 mm/hr to greater than 200 mm/hr). The rain rate distributions are assumed to be approximately lognormal. The three parameters characterizing the lognormal distribution can be calculated from the yearly maximum 5-minute rain rate data and the yearly total accumulated 1545 = - = = - BINGHAMTON, NEW YORK 20 YEARS (1953-1972) -- -- LOGNORMAL - Vv