Global Precipitation and Thunderstorm Frequencies. Part I: Seasonal and Interannual Variations

Abstract

Present and past weather reports from ∼15 000 stations around the globe and from the Comprehensive Ocean–Atmosphere Data Set from 1975 to 1997 were analyzed for the frequency of occurrence for and the percentage of the days with various types of precipitation (drizzle, nondrizzle, showery, nonshowery, and snow) and thunderstorms. In this paper, the mean geographical, seasonal, and interannual variations in the frequencies are documented. Drizzles occur most frequently (∼5%–15% of the time) over mid- and high-latitude oceans. Nonshowery precipitation is the preferred form of precipitation over the storm-track regions at northern mid- and high latitudes in boreal winter and over the Antarctic Circumpolar Current in all seasons. Showery precipitation occurs ∼5%–20% of the time over the oceans, as compared with < 10% over land areas except in boreal summer over Northern Hemisphere land areas, where showery precipitation and thunderstorms occur in over 20% of the days. Inferred mean precipitation inte... Abstract Present and past weather reports from ∼15 000 stations around the globe and from the Comprehensive Ocean–Atmosphere Data Set from 1975 to 1997 were analyzed for the frequency of occurrence for and the percentage of the days with various types of precipitation (drizzle, nondrizzle, showery, nonshowery, and snow) and thunderstorms. In this paper, the mean geographical, seasonal, and interannual variations in the frequencies are documented. Drizzles occur most frequently (∼5%–15% of the time) over mid- and high-latitude oceans. Nonshowery precipitation is the preferred form of precipitation over the storm-track regions at northern mid- and high latitudes in boreal winter and over the Antarctic Circumpolar Current in all seasons. Showery precipitation occurs ∼5%–20% of the time over the oceans, as compared with < 10% over land areas except in boreal summer over Northern Hemisphere land areas, where showery precipitation and thunderstorms occur in over 20% of the days. Inferred mean precipitation inte...