Chlorophyll a concentration (Chla.) is a key to understand global biogeochemical cycles and to estimate ocean primary production which is the index of the fish food. The ocean regions with high Chla. provide the food condition of the convergence of the fish to become the candidate of the fishery centers. Chla. mainly decides the ocean optical properties in Case 1 waters and the satellite can measure the ocean radiances which are in a good relationship with Chla.. It has been proved that the ocean color satellites can really measure the Chla. of the ocean on the global scale. The Chla. distribution images are produced from satellite data and the accuracy of Chla. depends on inversion algorithms. The algorithms based on blue-green bands ratio are suitable to be used as operational algorithms to retrieve Chla. from the normalized water-leaving radiances for Case 1 waters. Two inversion models of Chla. are established on thousands of global in situ measurement data. The average relative errors of the Chla. retrievals of the two models are 36.4% and 38.5% respectively. Many factors can affect the accuracy of Chla. retrievals, including the conditions of atmosphere, ocean and instruments. Since the blue-green ratio algorithms are the localized algorithms which are based on a large amount of in situ measurements, a lot of measurements should be taken in the north Pacific Fishery regions to improve the accuracy of the algorithms. The algorithms are seriously affected by the in situ data, both the ocean optical parameters and the Chla. should be carefully measured with some nice instruments. A Chla. distribution map was generated from a month of Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) data by the fusion techniques. The average of satellite-measured Chla. is 0.192 mg·m-3 in the whole north Pacific Fishery which is higher than ship-measured value with the average of 0.13 mg·m-3. The difference is mainly caused by th edifferent regions for the satellite measures of the Chla. in the coast areas around the Japanese islands with high Chla. more than 1 mg·m-3. The averages of Chla. in the middle part fishery are close between the satellite retrievals and the in situ measurements wit h0. 171 mg·m-3 and 0.15 mg·m-3 respectively and the values are also similar in the east part fishery with 0. 132 mg·m-3 and 0.12 mg·m-3 respectively. The ocean color satellite can really measures the Chla. in the north Pacific Fishery with high accuracy. The map of Chla. derived from SeaWiFS data shows the distribution of Chla. in the whole north Pacific Fishery which is very useful to analyzethe distribution of fishery centers. The map also shows the distributions of the ocean fronts and eddies, which are also beneficial in locating the fishery centers. The relationship between the Chla. map and the fishery centers should be carefully studied. The results show that the satellite-measured Chla. will become an important tool in the ocean fishery.
展开▼
