The applicability of the Global Precipitation Mission to detect and assess extreme rainfall events

Abstract

The global precipitation measurement mission (GPM) is the latest precipitation remote sensing satellite by NASA and JAXA. This study aims to assess the applicability of the GPM during extreme events. In particular: Hurricane Harvey (25-29 August) and a monsoon event in North-East India (9-13 August). This study shows that GPM can quantify and understand different types of extreme events. Validation with local rain gauges showed that GPM had average to good correlation coefficients and good POD values. Furthermore, GPM shows that it can correctly capture the occurrence of extreme events. The precipitation peaks of Harvey can be captured accurately with, for example, a Nash-Sutcliffe Efficiency (NSE) value of 0.71 at Houston NWS. The precipitation peaks of the monsoon event are also captured accurately with a NSE value of 0.62 at Shah Amanat. However, some over- and underestimation occurs. However, this can be explained due to faulty gauge data and due to miss sampling because a satellite can only take a snapshot measurement of a continuously changing extreme event. The characteristics of Harvey and the monsoon event and their key differences can also be distinguished. The GPM displays Harvey as relatively short and singular event with relatively high precipitation intensity, whereas the monsoon event is displayed as a relatively larger event with lower precipitation intensity. Furthermore, GPM shows that it can detect orographically enhanced precipitation in the monsoon area. The GPM also established that during Harvey the precipitation amount is higher inland than overseas. However, this is mainly due to the position of the hurricane eyewall, which causes the differences in precipitation for the period of Harvey around the shore.