Analyses of High-Resolution Merged Precipitation Products over China

On the basis of the merged precipitation observed by automatic meteorological stations and retrieved by the CMORPH (Climate Prediction Center Morphing technique) satellite, the merged precipitation product at temporal and spatial resolutions of 1 h and 0.1° (lat)×0.1° (lon), respectively, is developed by the National Meteorological Information Center. The quality of the product is assessed in terms of the mean error and root-mean-square error in the temporal-spatial distribution, the accuracy at different precipitation rates, and the merging effect in areas sparsely and densely covered by stations. The results indicate that (1) the regional mean error and root-mean-square error for the merged product decreased remarkably, and the extent of the change over the temporal-spatial distribution is weakened, although this trend is weaker in winter than in summer; (2) the merged precipitation presents a distribution of daily rainfall rates very close to that obtained by gauge analysis. Although the merged product overestimates light rains and underestimates heavy rains, both the mean error and root-mean-square error of the merged product are smaller than those of CMORPH in the same precipitation order, and the quality is improved further as the precipitation order increases; (3) In sparsely covered areas where there is no station, the merged product is controlled mainly by CMORPH. As the gauge number increases, however, the gauged-based precipitation plays a more important role than CMORPH. In contrast, in densely covered areas, the merged product is controlled mainly by the gauged-based precipitation. In summary, the merged product effectively takes advantage of the gauge observations and the product of the CMORPH satellite.