Frequencies and Characteristics of Global Oceanic Precipitation from Shipboard Present-Weather Reports
Abstract Ship reports of present weather obtained from the Comprehensive Ocean-Atmosphere Data Set are analyzed for the period 1958–91 in order to elucidate regional and seasonal variations in the climatological frequency, phase. intensity, and character of oceanic precipitation. Specific findings of note include the following: 1) The frequency of thunderstorm reports, relative to all precipitation reports, is a strong function of location, with thunderstorm activity being favored within 1000–3000 km of major tropical and subtropical landmasses, while being quite rare at other locations, even within the intertropical convergence zone. 2) The latitudinal frequency of precipitation over the southern oceans increases steadily toward the Antarctic continent and shows relatively little seasonal variation. The frequency of convective activity, however, shows considerable seasonal variability, with sharp winter maxima occurring near 381 latitude in both hemispheres. 3) Drizzle is the preferred form of precipitat...