Relationship between the Changjiang Diluted Water and SeaWiFS chlorophyll-a during summer

Abstract

Satellite chlorophyll-a distribution was analyzed with statistical analysis, K-means clustering. And proper satellite chlorophyll concentration to indicate the Changjiang Diluted Water (CDW) was found. During 1998-2006, the distribution of CDW controlled by the Changjiang summer freshwater discharge showed significant interannual variations. The Sea-viewing Wide field-of-view Sensor (SeaWiFS) chlorophyll-a showed that interannual variations of the spatial distribution of high satellite chlorophyll-a (>0.9-0.4 mg m-3) was well corresponded with distribution of low salinity CDW (<30-32), and that interannual variation of the CDW area was associated with the interannual variation of the Changjiang summer freshwater discharge. Correlation analysis between the high satellite chlorophyll-a and summer freshwater discharge showed that the area of relatively-high-satellite chlorophyll in August showed best correlation (R2&#8776

0.85, P<0.0001) with SFD in July. The second good correlation (R2&#8776

0.79, P<0.001) was shown between the area and SFD in August. The third (R2&#8776

0.58, P<0.02) was between the area in September and SFD in July. Correlation analysis indicated that low salinity, high satellite chlorophyll-a CDW spread further in the East China Sea after 1 to 2 months time lag of the discharge.