THREE†DIMENSIONAL STRUCTURE OF WIND†DRIVEN CURRENTS ACCOMPANIED WITH SECONDARY CIRCULATIONS AND THEIR EFFECTS ON THE THERMAL STRUCTURE OF LAKES AND OCEANS

Abstract

Wind-driven currents "WDC" play an important role on the material transport in lakes and oceans. Generaly, the horizontal profile of WDC is forecasted uniformly almost with 3% of U10 to the surface speed. However, Secondary circulations named "Langmuir Circulations : LCs†, which have axes in the wind direction, are often formed in WDC. When LCs are formed, it is suggested that the horizontal profile of WDC becomes the spatially periodic one which has the high-speed area and the low-speed area alternately. In the high-speed area, the surface speed is suggested much larger than 3% of U10. It is very important to estimate precisely the surface speed in the high-speed area in order to forecast accurately the material transport due to WDC. Furthermore, the vertical mixing by LCs is suggested to have an significant effect on the thermal structure in lakes and oceans because the maximum vertical speed of LCs is estimated about 1/3 of surface speed. In this study, the horizontal profile of WDC are observed by H-ADCP and the vertical profile of thermal structure are also observed by the thermistor chain in order to estimate the effects of LCs on them.