Seasonal and intraseasonal variability of surface chlorophyll <i>a</i> concentration in the South China Sea

Abstract

Seasonal and intraseasonal variability of surface chlorophyll a concentration in the South China Sea is explored using the NASA standard Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) monthly and 8-day level-3 products from 1997 to 2007. The link between the seasonal and intraseasonal variability of the chlorophyll and physical forcing is revealed. Continuous wavelet transform indicates that chlorophyll in the South China Sea presents pronounced seasonal, as well as intraseasonal, variability. Chlorophyll a variability shows significant correlation with wind speed in all five sub-regions, while significant correlation with sea surface temperature only appears in the northern Sea. Intraseasonal variability of chlorophyll appears mainly in the winter, with spectral peaks around 32–64 days. It shows high commonalities for some periods in the intraseasonal cycle between chlorophyll a and sea surface temperature, wind stress curl or wind speed using cross wavelet transform.