Comparing high-resolution gridded precipitation data with satellite rainfall estimates of TRMM_3B42 over Iran

摘要

To evaluate satellite rainfall estimates of Tropical RainMeasurement Mission (TRMM) level 3 output (3B42) (TRMM_3B42) over Iran(20°–45° N, 40°–65° E), we compared these data withhigh-resolution gridded precipitation datasets (0.25°×0.25° latitude/longitude) based on rain gauges (Iran Synoptic gauges Version 0902(IS0902)). Spatial distribution of mean annual and mean seasonal rainfall inboth IS0902 and TRMM_3B42 from 1998 to 2006 shows two main rainfallpatterns along the Caspian Sea and over the Zagros Mountains. Scatter plotsof annual average rainfall from IS0902 versus TRMM_3B42 for each 0.25°×0.25° grid cellover the entire country (25°–40° N,45°–60° E), along the Caspian Sea (35°–40° N, 48°–56° E), andover the Zagros Mountains (28°–37° N, 46°–55° E)were derived. For the entire country, the Caspian Sea region, and the ZagrosMountains, TRMM_3B42 underestimates mean annual precipitation by 0.17,0.39, and 0.15 mm day, respectively, and the mean annual rainfallspatial correlation coefficients are 0.77, 0.57, and 0.75, respectively. Themean annual precipitation temporal correlation coefficient for IS0902 andTRMM_3B42 is ~0.8 in the area along the Zagros Mountains, and ~0.6in the Caspian Sea and desert regions.