The Optimal Wind Direction for the Occurrence of Wind-Driven Coastal Upwelling Associated with “Aoshio” on the Southeast Shore of Tokyo Bay

Abstract

Whether the optimal wind direction for the occurrence of wind-driven coastal upwelling associated with "Aoshio" on the southeast shore of Tokyo Bay exists was not clear. In this study, Tokyo Bay was assumed to be a narrow, infinitely long channel with only the southeast shore and the northwest shore being its two boundaries, and the optimal wind direction for coastal upwelling associated with "Aoshio" on the southeast shore of this idealized channel was discussed. It is found that the optimal wind direction varies with wind duration. If wind duration is very short, the optimal wind direction is almost across the channel while, with the increasing wind duration, the optimal wind direction approaches gradually to be along-channel. This transition is attributed to the increasingly important role that played by the Coriolis force in the motion of the two-layered fluid with the increasing wind duration.