The Sensitivity of Rainfall Distributions to Time, Space, and the Environment over Kwajalein Atoll

The Intertropical Convergence Zone (ITCZ) causes focused rain maxima over the tropical oceans. This study uses observations from the ground-based Kwajalein S-band radar in the central Pacific ITCZ during two wet seasons to understand variations in oceanic rainfall characteristics and extremes in terms of spatial resolution, temporal averaging, and environmental conditions. Rain is first categorized as either convective or stratiform. Rainfall characteristics are then calculated on a series of temporal scales ranging from 10 min to 1 day and spatial scales ranging from 2 km to 128 km grids. Rain rates show a logarithmic tendency with an uptick after the 90th percentile of rainfall at all scales. Rain intensity and rain area are then compared to specific humidity and omega from the ERA-Interim reanalysis and sea surface temperature (SST) from the Earth System Research Lab (ESRL) to determine if a relationship exists between any of the environmental parameters and the observed rainfall characteristics. These results hold the potential to quantify how environmental factors may influence precipitation and precipitation extremes and to provide statistics to assess models at a variety of temporal and spatial scales.