Analysis of Overlap between Hourly and Daily Precipitation Extremes

This research examines both extreme hourly (MERRA2) and three-hourly (TRMM 3B42v7) and daily precipitation extremes in those same datasets. MERRA2 is a reanalysis dataset that assimilates many different observations including several satellite datasets, while the TRMM product is derived from the TRMM satellite’s precipitation radar and spaceborne microwave radiometers. Overlaps between daily and shorter-term extremes are examined for both datasets, as well as times when only a shorter term or daily extreme occurred. For arid and semi-arid regions, the overlap between the extremes of the two time periods is considerable, whereas for wetter regions there is much less overlap between these categories of extremes. In other words, in relatively dry regions, storms that produce extreme short-term precipitation are also the ones identified as extreme daily rain events, but this is less prevalent in wetter areas. The meteorological conditions for the different durations of events are also examined to seek similarities and differences in the meteorological conditions that lead to extremes of each category. This is of particular interest because it is hypothesized by this research that the shorter-term extremes are likely to be convective and limited by water vapor availability, while the longer-term extremes are likely associated with larger weather systems that are limited by available lift sustained over a longer period in addition to water availability. As water vapor increases in a warmer climate, this may have implications for precipitation extremes in the future.