Spatiotemporal evaluation of the GPM satellite precipitation products over the United Arab Emirates

The accurate measurement of rainfall intensity is always challenging due to high spatial and temporal variation of the precipitation, particularly on arid and semiarid regions. The United Arab Emirates (UAE) lies in an arid region with a high shortage of rainfall events. Thus, accurate and continuous monitoring for efficient management of water resources is of particular importance. There are many techniques and instruments that were developed for collecting and/or estimating precipitation. Recently, multi-satellite sensors were globally utilized over the past three decades to measure the precipitation. The Global Precipitation Measurement (GPM) satellite has a capability to detect and measure all types of precipitation using advanced instruments. This article validates the accuracy of the GPM IMERG (Integrated Multi-satellitE Retrievals from Global Precipitation Measurement) early, late and final rainfall products over the UAE using multiple spatial and temporal assessments over the period from Jan 2015 to Dec 2017. The IMERG early-run-product showed a good detection accuracy and low estimation error over the UAE except for the eastern part, while the late-run-product showed a slight improvement. The final-run-product showed the highest detection and low estimation error compared to other products. The correlation between rain-gauge and satellite data demonstrated a contradiction, which reveals that the early-run-product had the highest correlation. Nevertheless, the correlation with the final-run-product was quite lower than the early-run-product. Based on these results, the GPM IMERG final-run-product provides not only a better understanding of the rainfall variability and pattern over the UAE, but also could serve as a reliable product to complementing and/or substituting ground precipitation measurements for ungauged or poorly gauged regions. This paper presents results of one of the earliest assessments of the GPM IMERG products in the Middle East. The outcomes could pave the road for further improvement of the IMERG algorithms in the future.