Seasonal and interannual variability of chlorophyll in the East China Sea

Seasonal and interannual variability of chlorophyll in the East China Sea based on the remote sensing data of Sea-viewing Wide Field-of-View Sensor (SeaWiFS) was analyzed since the start of SeaWiFS mission in 1997 till the winter of 2009. At the same time, we also explore the time-lagged correlations between CHL and other measured by satellite sensors factors, which hypothetically can influence CHL dynamics: wind speed measured by QuickSCAT (August 1999-October 2009), and sea surface temperature (SST) measured by Advanced Very High Resolution Radiometers (AVHRR) aboard NOAA satellites (1997-2007) and MODIS-A (July 2002-December 2009). SST anomalies indicate water column stratification, which is closely connected to light and nutrient limitation of phytoplankton growth. Statistical methods including anomaly, sliding average were used to analyze the variability of Chlorophyll concentration. The results show that the range of interannual variations significantly exceeds the range of seasonal cycle, seasonal variation of Chlorophyll concentration represented a maximum in April, a minimum in June. The results identify the twice bloom in spring and autumn every year is common in the East China Sea.