Comprehensive evaluation of four high-resolution satellite precipitation products under diverse climate conditions in Iran

Abstract

High-resolution satellite-retrieved precipitation products are useful input data for hydrologic predictions and water resources management, especially in developing countries where the availability of ground-based rainfall measurements with high spatial coverage is very limited. In this study, four widely used satellite rainfall estimates (TMPA-3B42V7, TMPA-3B42RT, PERSIANN, and CMORPH) are evaluated with a dense raingauge network over six regions with various physiographic and climate conditions in Iran. Assessments are implemented at daily scale for different seasons during the five years period from 2003 to 2008. Overall, the results show that 3B42V7 leads to better performance than the other three products over different terrains. According to the value of relative bias (RBias) as one of the verification metric used in this study, 3B42V7 with an average value of 13.43% over all the regions matches best with the raingauge observations, while both PERSIANN and 3B42RT overestimate precipitation by 78.13% and 31%,respectively. On the other hand, CMORPH with RBias of -17.6% tends to underestimate the rainfall amount. Furthermore, the evaluations over different seasons indicate that the best performance for PERSIANN and both TMPA products is during the winter, while for CMORPH is during the autumn season. With respect to the critical success index (CSI) in order to assess the rain detecting skill of satellite products, one can conclude that PERSIANN leads to better estimations during the winter and summer, 3B42RT during the spring, and CMORPH during the autumn season. Generally, the implemented analyses in this research provide quantitative information of error characteristics associated with satellite precipitation products over different parts of Iran and thus will offer hydrologic users a better understanding of satellite rainfall estimates applicability in this area.

Assessment of GPM-IMERG and Other Precipitation Products against Gauge Data under Different Topographic and Climatic Conditions in Iran: Preliminary Results

“…Additionally, the GPM constellation satellites' product (IMERG) was superior to the TRMM Multi-satellite Precipitation Satellites (TMPA) product (3B42). Moreover, all three satellite/model products underestimated the precipitation in this region, a similar conclusion by Moazzami et al [13] and Javanmard et al [11] who tested 3B42 in this region. Such findings may be attributed to local wind and convective precipitation in this region so that satellites could not detect precipitation properly.…”

“…Another tool to determine precipitation at relatively fine temporal and spatial scale is satellite observation. During the last decade, many researchers have evaluated and used satellite data sets and some have found that the TMPA-3B42 post real-time product performed better than other products compared with the rain-gauges [9][10][11][12][13][14][15]. One of the disadvantages of TMPA-3B42 was the limited area of observation; it covered only the tropical and subtropical belts.…”

Evaluation of CHIRPS rainfall estimates over Iran

“…However, Moazami et al . () focused on a comprehensive evaluation of four satellite rainfall estimates over Iran, including PERSIANN, TMPA‐3B42‐V7, TMPA‐3B42RT and CMORPH. Their results show that in most cases the underestimation of rainfall is quite large at high rainfall ranges.…”

“…A number of different evaluations of satellite rainfall estimates have previously been carried out over Iran (e.g. Javanmard et al, 2010;Katiraie-Boroujerdy et al, 2013;Moazami et al, 2016;Alijanian et al, 2017). The evaluation of different satellite rainfall estimates reveals that the results vary in different areas (Katiraie-Boroujerdy et al, 2013).…”

“…The evaluation of different satellite rainfall estimates reveals that the results vary in different areas (Katiraie-Boroujerdy et al, 2013). However, Moazami et al (2016) focused on a comprehensive evaluation of four satellite rainfall estimates over Iran, including PERSIANN, TMPA-3B42-V7, TMPA-3B42RT and CMORPH. Their results show that in most cases the underestimation of rainfall is quite large at high rainfall ranges.…”