Applicability Assessment of GPCC and CRU Precipitation Products in China during 1901 to 2013

Two gridded precipitation datasets from the Climatic Research Unit (CRU) and the Global Precipitation Climatology Centre (GPCC) are evaluated using the station-observed precipitation over China for the period of 1901-2013 at the seasonal, annual, and interdecadal time scales, respectively. The main results are:Firstly, for the period of 1961-2013, both CRU and GPCC products are able to describe the temporal-spatial variation of precipitation in China, and both show a better performance in eastern China than in western China and in summer than in winter. On the annual and seasonal time scales, comprehensive comparisons are also performed through analyzing the percentages of absolute deviation, the root-mean-square errors, and the correlation coefficients between two products with the station observations. It is found that the CRU data shows large biases in the Tibetan Plateau and some other areas of large mountains, and the annual precipitation trend derived from CRU data is also smaller than that from station observations over areas such as the Altun Shan Mai, the Loess Plateau, southeastern China, and the lower reaches of the Yangtze River basin, while GPCC data is relatively more consistent with the station observations in both precipitation amount and trend. Secondly, for the period of 1901-1961, in-situ observed precipitation at 65 stations are used to compare with CRU and GPCC products. It is found that CRU shows large deficiencies to the west of 110°E in the arid and simi-arid regions in China, while GPCC agrees well with observations. Finally, the two gridded datasets and station observations for the period of 1961-2013 are used to compute the standardized precipitation index (SPI), which is then used to describe the degree of aridity in China. The results show that the GPCC is closer to the observations than CRU in terms of the dry and wet events variations in China. For instance, GPCC can capture the severe drought in the summer of 1997, but CRU cannot. In summary, this study suggests that GPCC is a better choices compared to CRU for studying the long-term precipitation trend in China.