Relative contributions of weather systems to mean and extreme global precipitation

This study presents the first global estimates of the relative contributions of different weather systems, i.e., tropical cyclone, center and front of extratropical cyclone, and others, to mean and extreme precipitation. An objective method of classification of the precipitating weather systems was used with a reanalysis data set and a satellite-based precipitation product for 2001-2010. Tropical cyclones, extratropical cyclones with associated fronts, and other weather systems contribute about 4%, 37%, and 59%, respectively, of the global (60 degrees S-60 degrees N) mean precipitation. The relative contributions of the weather systems were found to be different both in terms of the different classes of precipitation intensity and in terms of the different temporal scales of precipitation. Tropical cyclones and extratropical cyclones produced greater contributions to extreme hourly precipitation than to annual precipitation in most of the oceanic regions of their activity. The contributions of tropical cyclones to extreme precipitation showed clear peaks on temporal scales of 24-72h. The contributions of extratropical cyclones showed less dependence on the temporal scale than tropical cyclones. Consideration of combinations of multiple weather systems revealed that in eastern North America and East Asia, substantial portions (22% and 19%, respectively) of the extreme 24h precipitation related to tropical cyclones are contributed by the coexistence of tropical cyclones and fronts. However, such contributions were found rarely in other land regions. On most temporal scales, fronts at locations remote from the centers of extratropical cyclones were found to contribute to extreme precipitation as much as the centers of extratropical cyclones.