Abstract
To provide necessary data to mass balance models in Lake Shinji, Shimane Prefecture, a methodology for the estimation of gross primary production (Pg) at the surface of the lake using SPOT HRV data was proposed and evaluated using satellite/in-situ water quality data sets acquired in 1995-1998. The procedures of the methodology are, 1) the offset values of HRV bandl (XS1) and band2 (XS2) are calculated from the mean and the standard deviation of XS1 and XS2 in the lake area only, 2) the area average of surface chloropyll-a concentration (Chl.a) is calculated from those of HRV data after offset removal, 3) the average Pg for the whole lake surface (Pg) at the satellite observation time is estimated using the estimated Chl.a from SPOT HRV data. Rough estimations of Pgs based on the proposed methodology were within the range of about 50-700mgC/m3/hr. It was found that Pg in the summer and the autumn was usually 6 to 10 times higher than those in the spring, and Pg under algal bloom condition was twice higher than those of the usual condition even in the same season.
