Contributions of Local and Remote Atmospheric Moisture Fluxes to East China Precipitation Estimated from CRA-40 Reanalysis

Abstract

China Meteorological Administration (CMA) recently released its 40-yr (1979–2018) global Chinese reanalysis (CRA-40) dataset. To assess performance of the CRA-40 data in quantifying the regional water cycle, contributions of local and remote atmospheric moisture fluxes to precipitation in East China derived from CRA-40 are compared with those derived from the ECMWF reanalysis version 5 (ERA-5). Observed precipitation and evaporation data are also used for validation. As for mean precipitation, CRA-40 matches the observation better in winter and spring than in summer, with a larger wet bias (1.41 mm day−1) in summer than that in ERA-5 (0.97 mm day−1), particularly over South China. The conservation of atmospheric water vapor over East China measured by CRA-40 is comparable to that of ERA-5. Both reanalyses show a dominant role of the remote moisture transport in the East China precipitation. In comparison, the annual precipitation induced by the moisture influx from the west of the study domain in CRA-40 is 80 mm less than that in ERA-5. The recycling ratio of annual mean precipitation in CRA-40 is approximately 21.1%, slightly larger than that in ERA-5 (20.1%). The maximum difference of each hydrological component between the two datasets appears in the summer horizontal moisture influx (3.57 × 107 kg s−1; ERA-5 is larger) and winter runoff (1.84 × 107 kg s−1; CRA-40 is larger). CRA-40 shows better performance than ERA-5 in capturing the interannual variability of precipitation over East China, as evinced by a higher correlation coefficient with the observation (0.77 versus 0.33). The trend of summer precipitation since 2011 is better reproduced in CRA-40. Both reanalyses show prominent contribution of the southern moisture influx to the interannual variation of precipitation. This study demonstrates the reliability of CRA-40 in representing the hydrological cycle over East China and provides a useful reference for future application of CRA-40 in water cycle studies.