Some characteristics of precipitation and dry periods on Long Island

Six years of sequential hourly precipitation data are used to investigate the frequency functions of precipitation and dry periods at Brookhaven National Laboratory on Long Island, New York. The dry period frequency function is exponentially distributed when the precipitation and dry periods are classified by events based on meteorological and synoptic conditions. The ensemble precipitation frequency function is not exponentially distributed but is a composite of several distinct frequency functions which are characteristic of nonconvective and convective precipitation types. These precipitation-type frequency functions are exponentially distributed; hence individually they may be modeled as Markov processes.