The spatial distribution of chlorophyll-a in Changjiang River estuary and adjacent sea in spring

Chlorophyll-a (Chl-a) retrieval in case II waters is of intense research now. And due to the high turbidity of case II waters, most of the Chl-a information we have retrieved is the signal of suspended sediment concentrations. In order to improve the accuracy, we not only study the new retrieval algorithm, but also get more in-situ data sets. Thus, this paper studies the in-situ data in the Changjiang River Estuary and adjacent sea from Apr. 5th to May 5th in 2007, and the results show that the Changjiang diluted water (CDW) extends offshore with a bimodal structure during the observation, one extending toward the southeast, the other toward the northeast, the main axis of the CDW extending toward the northeast. There exists two centers of higher Chl-a concentration near the Changjiang River mouth, (122.45E,31.75N) and (123.2E, 30.5N), and the maximum concentrations have reached 6.5ug/L,6.3ug/L respectively. The Chl-a concentration would be increased significantly by the continual strong winds. The horizontal Chl-a maximum distribution is closely related to the position of CDW and the current structure.