Assessment of global precipitation datasets and their application in drought monitoring (Case study: Karkhe basin, Iran)

Lack of reliable long term data of precipitation, required for hydrometeorological studies, is a major challenge in most of weather stations of Iran. The present study aims to analyze the possibility of using global precipitation data as an alternative to the in situ observations. For this purpose, precipitation data collected from three global datasets namely APHRODITE, GPCC, and CRU were studied over a period of 30 years (1978-2007) for three synoptic stations located within Karkhe basin; Kermanshah, Khoram-Abad, and Hamedan. In addition to the total amount of precipitation the Standardized Precipitation Index (SPI) was also calculated using data retrieved from these three datasets. The obtained values were compared with observed ones. The obtained results revealed that different global databases perform differently in various climatic regions. However, in general, CRU at Kermanshah station, and APHRODITE at Khoram-Abad and Hamadan station, outperformed the others. For drought monitoring, based on annual SPI index, CRU by 83 percent of correct drought class recognition at Kermanshah station and GPCC by 83 and 70 percent of correct drought class recognition at Khoram-Abad and Hamadan stations, respectively, showed the best performance.