Precipitation effect on surface salinity and temperature in the Yatsushiro Sea

Field observation was carried out during July 2016 in Minamata Bay of Yatsushiro Sea, measured data of temperature and salinity of five stations has been used for comparing the numerical simulation based on Princeton Ocean Model (POM). Simulation results showed deviations existed between simulated and measured data, especially the salinity field, which was probably caused by the increased precipitation during plum rain season. Therefore, a new precipitation module and modified heat flux forcing for POM were built to present the rainfall effect of salinity and temperature. It is indicated that the accuracy of predicted temperature and salinity was improved to some extent. In contrast with the previous simulation, deviations were reduced significantly. Nevertheless, simulation results of new model under rainy and sunny conditions showed the cooling impact of precipitation was slight, which may be caused by the daytime observation and solar radiation was dominated. However, this study has shown that precipitation effect is an important factor for surface numerical simulation during rainy season.