Determination of primary production in the Japan coast the data of NIMBUS-7,CZCS
Yasuhiro Sugimori, Hajime Fukushima, Yasuhiro Senga
School of Marine Science and Technology, Tokai University
Orido, Shimizu, Japan
Abstract
The phytoplankton pigment concentrations around Japan inland sea were observed using data of Coastal Zone Scanner (CZCS). Distinct meso-scal,e eddies at Oyashio-Khuroshio front and detailed mixing patterns could be inferred sixth the pigment picture. Highly reflective patterns were observed in each channel of image in late spring.
Through image processing, it is found that aerosol types may be different in the Pacific side and the Japan Sea, where the Godo-Clark scheme will not be applicable. The in-water algorithm might also be different.
Introduction
A typical example of the application of the NIMBUS-7, CZCS was the study of warm core ring structure (Gordon, 1982). The CZCS was the best satellite sensor for the determination of distribution of phytoplakton pigment. As fundamental study to formulation of a chlorophyll algorithm Hovis (1980) examined the spectral patterns of upward irradiant from water of various chlorophyll concentration (in the paper, Chlorophyll or pigment equal to mean Chlorophyll plus Chaeophytin). Fig.1 shows clearly that the upward irradiance patterns vary strongly with chlorophyll concentration. Thus, the distribution might be easily derived from data of each channel. The upper indication in Fig. 1 shows the band width of each channel of which CH-4 can present the definite absorption of light by chlorophyll production.
Model for satellite determination of chlorophyll
It is well estimated by all optical oceanographers that Gordon-Clark Model, using the optical-nol method in near infrared radiation emitted from ocean surface, can determine the distribution of chlorophyll in the upper ocean. Fig 2 shows their regression lines (dashed lines). The relationship between chlorophyll content and spectral irradiance varies because of changes with season, religion and species. This is shown in Fig.2 by data from S&W refer to Morel, Clark Gordon, Sugihara and smith & Wilson respectively
The solid line in Fig.2 is the regression of our data from around Japan coast. Thus, the chlorophyll content can be found through the spectral irradiance by,
Log C = Log a + b Log R ----------------------(1)
R =Ch-1/Ch-2m or Ch-2/Ch-3 ---------------------------(2)
Unfortunately, our field data were not coincident with the CZCS images, so we used Gordon-Algorithm as the first attempt.
Determination of chlorophyll distribution
Picture 1 shows the chlorophyll l distribution at the south eastern end of Main-island of Japan. The Euroshio, which has low chlorophyll concentration, is flowing from SW to E. The Oyashio and coastal water with high chlorophyll concentrations are trapped by large frontal eddy. Even south of the Kusoshio, a high chlorophyll concentration can be distinctly seen. Thus, there must be eddies causing upwelling and vertical mixing to support the primary production.
Fig.1 Upward spectral irradiance just below the surface by each ch.1 content water
(Hovis, 1990)
Picture 1, CZCS-derived pigment image(1981, April,14)
