Assessment of summer monsoon precipitation derived from five reanalysis datasets over East Asia

Abstract

Precipitation, which is the predominant component of the East Asian summer monsoon (EASM), may have large uncertainties among reanalysis datasets. We comprehensively evaluate the performance of five reanalysis datasets in reproducing the EASM precipitation. These datasets are NCEP/NCAR Reanalysis 1 project (NCEP1), NCEP/US Department of Energy Atmospheric Model Intercomparison Project II reanalysis (NCEP2), Japanese 25‐year Reanalysis project (JRA‐25), Interim ECMWF Reanalysis (ERA‐Interim), and Modern Era Retrospective‐analysis for Research and Applications (MERRA). Results show that the five reanalysis datasets can generally reproduce the climatology and interannual variability of EASM precipitation. Especially, MERRA and ERA‐Interim have the highest skills. Considering different‐class precipitation, large uncertainties exist in the category of non‐rainfall and heavy rainfall. The five reanalysis datasets overestimate the non‐rainfall frequency, and JRA‐25 and NCEP2 overestimate the heavy rainfall frequency. The well‐known interdecadal variation around the mid‐1990s can also be better depicted by ERA‐Interim and MERRA. For the linear trend of precipitation, only MERRA can reasonably reproduce the increasing tendency over southern China and the western Pacific and the decreasing tendency over the Indo‐China Peninsula. Based on EOF analysis, the spatial–temporal structure of EASM precipitation has been examined. MERRA, NCEP1 and ERA‐Interim can better capture both the spatial patterns and principle components of the first two EOF modes. Based on our evaluation, the preferential reanalysis datasets for investigating the EASM precipitation are ERA‐Interim and MERRA, which also permit the more precise investigation of interannual to decadal variability.