Effect of wind on seawater exchange in Matsushima Bay

Abstract

To examine seawater exchange in Matsushima Bay, we analyzed monthly tempera­ ture and salinity data, obtained by the Miyagi Prefecture, and temperature monitoring data pro­vided by the Sena and Varns Corporation. The difference in surface temperature, between wa­ter inside and outside of the bay, is larger in early summer and late summer, and decreases in mid summer, indicating two peaks in the warming season. A temperature fluctuation with a several-day period was strongly correlated to the northwest-southeast wind component, which dominated from early summer to fall. The correlation indicates that the temperature decrease was induced about 2 days after southeastward wind events. In order to clarify these mecha­nisms, we employed the Regional Ocean Modeling system (ROMS) using observed atmospheric data. After reproducing the temperature variation from spring to fall. we found that over a several-day period, wind induced seawater exchange and variation in the temperature differ­ence between water inside and outside of Matsushima Bay. Monitoring data and model results confirmed that an internal tide was generated in the bay during the formation of a thermocline that occurred after the southeastward wind. These results indicate that wind-induced seawater exchange occurs in Matsushima Bay.