Acta Geographica Sinica ›› 2003, Vol. 58 ›› Issue (4): 483-493.doi: 10.11821/xb200304001

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Estimation of Ocean Primary Productivity by Remote Sensing and Introduction to Spatio-temporal Variation Mechanism for the East China Sea

LI Guosheng1, WANG Fang1, LIANG Qiang1, LI Jilong2   

  1. 1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China;
    2. Chinese Academy of Fishery Sciences, Beijing 100039, China
  • Received:2003-01-09 Revised:2003-03-05 Online:2003-07-25 Published:2003-07-25
  • Supported by:

    The Key Project for the National Ninth Five-Year Plan, No.HY126-06-04-04

Abstract:

According to calculation results of ocean chlorophyll concentration based on SeaWiFS data by SeaBAM model and synchronous ship-measured data, this research set up an improved model for Case-I and Case-II water respectively. The monthly chlorophyll distributions in the East China Sea in 1998 have been obtained from this improved model on the calculation results of SeaBAM. The relative coefficient analysis between the ship-measured chlorophyll concentration and the calculation results of the improved model shows that the relative coefficient is 0.5752, which means they have obvious dependence. The fact that the coefficient of linear regressive equation is nearly 1 confirms their dependence further. Therefore, it can be said for certain that the improved model is suitable for calculation of the chlorophyll distribution for Case-I and Case-II water in the East China Sea. The euphotic depth distribution in 1998 in the East China Sea is calculated by using remote sensing data of K490 from SeaWiFS according to the relation between the euphotic depth and the oceanic diffuse attenuation coefficient. With the data of ocean chlorophyll concentration, euphotic depth, ocean surface photosynthetic available radiation (PAR), daily photoperiod and optimal rate of daily carbon fixation within a water column, the monthly and annual primary productivity spatio-temporal distribution in the East China Sea in 1998 have been obtained based on VGPM model. Based on analysis of those distributions, the conclusion can be drawn that there is a clear bimodality character of primary productivity in the monthly distribution in the East China Sea. In detail, the monthly distribution of primary productivity stays lowest level in winter and rises rapidly to the peak in spring. It gets down a little in summer, and gets up a little in autumn. The daily average of primary productivity in the whole East China Sea is 560.03 mg/m2/d, which is far higher than the average of subtropical ocean areas. The annual average of primary productivity is 236.95 g/m2/a, which is fit with the primary productivity obtained from the investigation in the Kuroshio zone in the East China Sea. The research on the seasonal variety mechanism of primary productivity shows that several elements that affect the spatio-temporal distribution may include the chlorophyll concentration distribution, temperature condition, the Yangtze River dilute water variety, the euphotic depth and ocean current variety etc. But the main influencing elements may be different in each local sea area.

Key words: East China Sea, primary productivity, chlorophyll concentration, remote sensing algorithms, spatio-temporal variation, mechanism