Remote determination of the sea-surface chlorophyll a concentration along the coastal water by FY-1 satellite
Lin Shouren, Han Along and Zhang Gongwei
Zehijanna Remote Sensing Center,
The Second Institute of Oceanography,
SOA, Hangzhou, PRC
Abstract
This paper introduces a result of studying ocean colour experiment of "FY-1" satellite. A principle of spectral equivalent albedo is defined as FY-1 data processing. The ratio of FY-1 VHRSR's channe 1-3 and channe 1-4 equivalent albedo is employed to estimated the sea-surface chlorophy11 a concentration. Chlorophy11 a concentration is calculated from following formula:
Nc = a * R-b (a = 3.3336 and b = 5.2316)
Where a and b are both contant values.
Finally, the distribution map of sea-surface chlorophyll a concentration retrieved form FY-1 data (Sep. 21, 1988) demonstrates that sea-surface chlorophy11 a concentration is between 0.6 and 5.0 mg/m
3 at Bohai Bay. This result agrees with those of surveying along the East and South China Sea.
Introduction
The change of ocean color is due to the suspended matter, such as the particulate matter, phytoplankton, and the dissolved material in the water. Fishing ships need the ocean color data to locate fish population, and to optimize ship routes, thereby, improving catch efficiency, and reducing costs. The research user group needs only continuous availability of ocean color data to specify quantitatively the ocean's role in the global carbon cycle and to determine the magnitude and variability of annual primary production by marine phytoplankton on a global scales. Recently, remote measurement of the change of ocean color has become very important.
In the oceanography from space, the remote sensing of ocean color focuses on the measurement of chlorophyll concentration. From 1978 to 1986, the Coastal Zone Color Scanner (CZCS)
aboard the Nimbus-7 satellite provided the first ocean color data. During this period researchers demonstrated that:
- The technology of remote sensing can be used to survey and map the distribution of chlorophyll on the global scale. (1) (2) (3)
- An algorithm of G/B ratio for estimating sea surface chlorophyll concentration is available. Ratio of CZCS' band-1 (443nm) is used for open ocean in which the chlorophyll concentration is between 0.03-1.50mg/m3. And the ratio of band-2 (520nm) and band-3 for coastal zone in which the chlorophyll concentration is higher than 1.5mg/m3. (4) (5)
FY-1 satellite is a polar orbiting satellite which was designed and launched by China. Its main mission is observing meteorological phenomena from space. Besides this, a mission of remote sensing of ocean color experiment was carried out. (6)
