Decadal Variability in the Yellow and East China Seas as Revealed by Satellite Ocean Color Data (1979-2003)

Satellite ocean color data from the Coastal Zone Color Scanner (CZCS) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) are examined to investigate decadal trends in the Yellow and East China Seas (YECS). Our goal is to determine whether there have been changes in chlorophyll concentration and suspended sediment as indicated by changes in satellite-derived optical properties during the past two decades. We compare water-leaving radiance measurements at 443 nm and 555 nm1, and discuss possible reasons for the changes observed (whether they are artifacts of the different sensors and algorithms or real changes in the water properties). The CZCS pigment data were converted to chlorophyll concentration using an algorithm derived from in situ data to be consistent with the SeaWiFS chlorophyll derived by the OC4 algorithm (O'Reilly et al. 2000). The shallow coastal areas of the YECS exhibited high water-leaving radiance in the 555-nm band (Lw555) during both time periods, indicating that these waters are sediment-dominated case-2 waters. Between the CZCS era (1978-1984) and the SeaWiFS era (1998-2002), Lw443 increased in these areas by 17% 67-108%. In the deeper waters that are considered case-1 during summer, Lw443 decreased by 25%chlorophyll and colored dissolved organic matter (CDOM). Between the CZCS and SeaWiFS eras, the average chlorophyll concentration (based on case-1 algorithms) increased by 15-60% in these offshore deep waters. For comparison with the trends found in satellite data, we examined in situ data from 61 stations located off the western coast of Korea that had been sampled six times per year between 1978 and 2002.

SON Seunghyun;  CAMPBELL Janet;  DOWELL Mark;  YOO Sinjae; 

2006-01-24

NATL INST SCIENCE COMMUNICATION

JRC31175

https://publications.jrc.ec.europa.eu/repository/handle/JRC31175,