Study on detection of coastal water environment of China by ocean color remote sensing

摘要

Coastal water environment is essentially enhanced by ocean color which is basically decided by substances concentration in water such as chlorophyll, suspended material and yellow substance. It is very difficult, even not possible, to detect water color by expensive ship routing, because of its temporal and spatial variety of feature and scales in the very complicated dynamical system of coastal water. With the development of satellite technique in the last 20 a, space sensors can be applied to detect ocean color by measuring the spectra of water-leaving radiance. It is proven that ocean color remote sensing is a powerful tool for understanding the process of oceanic biology and physics. Since the 1980s, great attention has been paid to the advanced remote sensing technique in China, especially to development of satellite programs for the coastal water environment. On 7 September 1988, China launched her first polar orbit satellite FY- 1A for meteorological and oceanographic application (water color and temperature) and the second satellite FY- 1B two years later. In May 1999, China launched her second generation environment satellite FY- 1C with higher sensitivies,more channels and stable operation. The special ocean color satellite HY - 1 is planned to be in the orbit in 2001, whose main purpose is to detect the coastal water environment of China seas. China is also developing a very advantageous sensor termed as Chinese moderate imaging spectra radiometer (CMODIS) with 91 channels, which will be a good candidate of the third generation satellite FY-3in 2003.The technical system of ocean color rermote sensing was developed by the Second Institute of Oceanography (SIO), State Oceanic Administration (SOA) in 1997. The system included data receiving, processing, distribution, calibration, validation and application units. The Hangzhou Station of SIO, SOA has the capability to receive FY- 1 and AVHRR data since 1989. It was also a SeaWiFS scientific research station authorized by NASA, USA to free receive SeaWiFS data from 16 September 1997.In the recent years, the local algorithms of atmospheric correction and inversion of ocean color have been developed for FY - 1C and SeaWiFS, to improve the accuracy of the measurement from satellites efficiently. The satellite data are being applied to monitor coastal water environment, such as the spatial distribution of chlorophyll, suspended material and yellow substance, red tide detection and coastal current study. The results sbow that the ocean color remote sensing has latent capacity in the detection of coastal water environment. In consideration of the update technique progress of ocean color remote sensing and its more important role in the detection of coastal water in the 2000s, some suggestions are set forth, which would be beneficial to the design of a cheaper but practical coastal water detection system for marine environment preservation.