Effects of chlorophyll on upper ocean temperature and circulation in the upwelling regions of the South China Sea

The effects of chlorophyll on upper ocean temperature and circulation in the two upwelling regions of the South China Sea are investigated by comparing results of two experiments using the solar radiation penetration scheme with and without the effects of chlorophyll. In boreal winter, the sea surface temperature anomalies were negligible with the existence of chlorophyll throughout most of the South China Sea because of the deep mixed layer. The strong mixing stirred by surface winds brings the cold water into the mixed layer and cancels out heating due to the effect of chlorophyll. In boreal summer, the high chlorophyll concentration in the upwelling region southeast of Vietnam cools the upwelling water below the mixed layer and leads to lower sea surface temperatures. The present study confirms the processes proposed by previous studies in the equatorial Pacific that indicate that the mixed layer depth is important to the response of the surface temperature and current to biological heating.