EFFECTS OF SEA SURFACE TEMPERATURE AND ITS DIURNAL VARIATION ON DIURNAL VARIATION OF RAINFALL: A PARTITIONING ANALYSIS BASED ON SURFACE RAINFALL BUDGET

The effects of sea surface temperature (SST) and its diurnal variation on diurnal variation of rainfall are examined in this study by analyzing a series of equilibrium cloud-resolving model experiments which are imposed with zero large-scale vertical velocity. The grid rainfall simulation data are categorized into eight rainfall types based on rainfall processes including water vapor convergence/divergence, local atmospheric drying/moistening, and hydrometeor loss/convergence or gain/divergence. The rainfall contributions of the rainfall types with water vapor convergence are insensitive to the increase in SST from 27℃ to 29℃ during the nighttime, whereas they are decreased during the daytime. The rainfall contributions of the rainfall types with water vapor convergence are decreased as the SST increases from 29℃ to 31℃ but the decreases are larger during the nighttime than during the daytime. The rainfall contributions of the rainfall types with water vapor convergence are decreased by the inclusion of diurnal variation of SST with diurnal difference of 1℃ during the nighttime, but the decreases are significantly slowed down as the diurnal difference of SST increases from 1℃ to 2℃. The rainfall contributions of the rainfall types with water vapor convergence are insensitive to the inclusion of diurnal variation of SST during the daytime.