Abstract
Launched in 2014, the Global Precipitation Measurement (GPM) mission aimed at ensuring the continuity with the Tropical Rainfall Measuring Mission (TRMM) launched in 1997 that has provided unprecedented accuracy in Satellite Precipitation Estimates (SPEs) on the near-global scale. Since then, various SPE versions have been successively made available from the GPM mission. The present study assesses the potential benefits of the successive GPM based SPEs product versions that include the Integrated Multi–Satellite Retrievals for GPM (IMERG) version 3 to 5 (–v03, –v04, –v05) and the Global Satellite Mapping of Precipitation (GSMaP) version 6 to 7 (–v06, –v07). Additionally, the most effective TRMM based SPEs products are also considered to provide a first insight into the GPM effectiveness in ensuring TRMM continuity. The analysis is conducted over different geomorphic and meteorological regions of Pakistan while using 88 precipitations gauges as the reference. Results show a clear enhancement in precipitation estimates that were derived from the very last IMERG–v05 in comparison to its two previous versions IMERG–v03 and –v04. Interestingly, based on the considered statistical metrics, IMERG–v03 provides more consistent precipitation estimate than IMERG–v04, which should be considered as a transition IMERG version. As expected, GSMaP–v07 precipitation estimates are more accurate than the previous GSMaP–v06. However, the enhancement from the old to the new version is very low. More generally, the transition from TRMM to GPM is successful with an overall better performance of GPM based SPEs than TRMM ones. Finally, all of the considered SPEs have presented a strong spatial variability in terms of accuracy with none of them outperforming the others, for all of the gauges locations over the considered regions.
Highlights
Precipitation is a key component of the water cycle, which is facing unprecedented pressure due to the combined effects of population growth and climate change
This section aims at presenting which Satellite Precipitation Estimates (SPEs) between Global Precipitation Measurement (GPM) and Tropical Rainfall Measuring Mission (TRMM) considered in this study provides the most accurate precipitation estimates over Pakistan
At the regional scale and monthly time step, Integrated Multi–Satellite Retrievals for GPM (IMERG)–v03 outperformed IMERG–v04, which is in line with previous observations that were made at the daily time step over China [32,33]
Summary
Precipitation is a key component of the water cycle, which is facing unprecedented pressure due to the combined effects of population growth and climate change. Precipitations are generally retrieved from sparse and unevenly distributed gauges network introducing large uncertainty over the remote regions, such as tropical forests, mountainous, and desert regions. In this context, Satellite Precipitation Estimates (SPEs) offer the possibility to monitor precipitation on regular grids at the near-global scale representing an unprecedented measurement opportunity. From the success of TRMM based SPEs, a new generation of SPEs took advantage of previous SPEs to estimate precipitation over larger time window This is the case with PERSIANN–Climate Data Record (PERSIANN–CDR) [7], Multi–Source Weighted–Ensemble Precipitation (MSWEP) [8], and Climate Hazards Group InfraRed Precipitation (CHIRP) with Station data (CHIRPS) [9]. These SPEs have proven effective to follow regional drought processes [10,11,12] and long term hydrological survey [12,13]
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