Analysis Of High-resolution Merged Precipitation Products Over China

Based on the merged precipitation observed by Automatic Meteorological Stations(AWS) and retrieved by the satellite of CMORPH, the merged precipitation product at hourly/0.1°at/lon temporal-spatial resolution is developed by National Meteorological Information Center. In this paper, the quality of the product is assessed from the points of bias temporal-spatial distribution, the diurnal cycle of precipitation over each area, monitoring capacity of the persistent precipitation process. The main factors affect the accuracy of the merged precipitation are also discussed here. The main results of this research can be summarized in the following items:1) The merged product is effectively used the advantages of the AWS observations and satellite product of CMORPH and more reasonable both at the precipitation quantity and spatial distribution. Bias of the merged product is decreased remarkably, the regional bias and relative error is-0.28and-4.4%respectively. The extent of change over temporal-spatial distribution is weakened meanwhile the spatial correlation coefficient reaches0.983.; Bias of merged product are smaller than CMORPH in the same precipitation order, and the quality is improved further with the precipitation order increases especially the order reaches30mm/d. Along with the increase of total time, the result of merged product gets more significant improvement.2) Station intensity plays an important role both in dense-stationed area and sparse-stationed area, the more gauges, the smaller bias between the merged product and the AWS observations. And terrain height affects the accuracy of the merged product, more gentle the terrain height changes, the smaller bias between the merged product and the AWS observations. While the concern between satellite product of CMORPH and topographic variation is not big.3) Expect the Tibetan Plateau, the merged product show the diurnal cycles of precipitation over other regions very close to the AWS observations. While the satellite product of CMORPH failed to capture the major morning peak over Yangtze Rivers and South China, and show the precipitation peak earlier or later over other regions.4) The merged product can capture the precipitation process very well, the mean bias of two rainfall process over Yangtze River and South China is only-0.016、-0-02mm/h, respectively. The merged product have a definite advantage in the quantitatively rainfall monitoring, can show the rainfall structure of super typhoon "FANAPI" of different landing process.