Diurnal Variations of the Meiyu/Baiu Rain Belt

The present study has used reflectivity data from 8-year observations of the TRMM precipitation radar to investigate diurnal variations of the Meiyu/Baiu rain belt associated with the Meiyu/Baiu frontal zone and their relations to diurnal variations on both sides of the frontal zone. A front-relative coordinate system has been designed for analysis. It is found that reflectivity in the frontal zone has a remarkable diurnal cycle that peaks in the early morning. Meanwhile, reflectivity both south and north of the frontal zone possesses a distinct diurnal cycle with a different phase from that in the frontal zone and has a peak in the late morning and afternoon. Based on the analysis, a possible regulation of the diurnal cycle of the Meiyu/Baiu rain belt through the thermally forced diurnal evolution of rainfall systems on both sides of the frontal zone is suggested.