Estimation of the Primary Productivity in Pearl River Estuary Using MODIS Data

Based on a modified Vertically Generalized Production Model (VGPM), the primary productivity in the Pearl River Estuary, China, was estimated using the Moderate Resolution Imaging Spectroradiometer (MODIS) data. A regional parameterization of euphotic depth from diffuse attenuation coefficient at 490 nm was developed in order to improve the accuracy of VGPM. An empirical algorithm using the fluorescence line height to retrieve chlorophyll-a concentration was also employed for the estuarine waters. The modified VGPM was applied to MODIS data for primary productivity estimation. The results indicated a higher productivity in summer and autumn. The average values of the primary productivity in summer and autumn were over 300 mg m(-2) day(-1) while in spring and winter, the values were about 250 mg m(-2) day(-1).