Compared to the coastal area, the central yellow sea showed more significant seasonal variation of Chl a. Both the highest (1.58 +- 1.09 mg m-3, n = 13) and the lowest Chl a (0.18 +- 0.05 mg m-3, n = 7) were observed in this area during the April and August cruises, due to the spring bloom and the strong summer stratification, respectively. The seasonal patterns of sea surface Chl a mearsured by satellites at the coastal (D1) and central (D5) stations were consistent with the in situ measurements.