The quasi-global geographical distribution of precipitation system scale

The scale of precipitation systems can provide important information to acquire a better understanding of formation mechanism and environmental effects of precipitation as well as model promotion. However, the global geographical distribution of precipitation system scale remains poorly known from previous studies. This study uses the latest Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) data to get global patterns of precipitation system scale by grouping the contiguous rainy gridboxes during 2015-2018. Our results show that the large precipitation systems (>10³ km) occur more frequently over ocean and the midlatitude land areas with low precipitation amount such as Siberia as well as the western and central parts of North America. The most apparent seasonal variation of precipitation system scale occurs over midlatitude ocean along with the northern and southern coast of South America. Most regions of the world have the highest peak in the late afternoon at around 17:00 local time (LT). In a statistical average, the relationships between scale and other precipitation properties including amount, frequency, intensity and duration all seem to be positive. The strongest associations of scale with amount, frequency, intensity and duration all occur over tropics and ocean with the highest correlation coefficient greater than 0.8.