Application of GCM Outputs Into Projection of Water Quality in Tokyo Bay

Abstract

In Tokyo Bay, water quality has been deteriorated due to human activities in river basins flowing into Tokyo Bay. Anoxia or hypoxia is one of the most significant water quality problems in Tokyo Bay, and previous studies revealed that the occurrence of hypoxia is controlled by wind stress, river discharge and strong wind effect. In particular, strong wind has a great role in the sudden increase in dissolved oxygen in the lower layer of the bay head. In recent years, meteorological conditions have changed evidently, such as flood disaster due to the increase in strong rainfall intensity. The change in meteorological conditions may also change wind speed and wind direction in the future. Therefore, to project water quality in Tokyo Bay, it is important to understand the future wind conditions. This study thus aims to investigate the applicability of Global Circulation Model (GCM) into the projection of wind conditions over Tokyo Bay by using 12 different GCM models. As a result, it is found that bias correction using cumulative density function should be used for the projection instead of using bias correction based on normal distribution.