抄録
The objective of this study is to monitor the Trophic State Index (TSI) in six typical eutrophic lakes in Japan (Lake Shinji, Lake Nakaumi, Lake Kojima, Lake Biwa, Lake Suwa, and Lake Kasumigaura) using 500-m resolution MODIS data provided from JAXA. As a result, the following matters were clarified. 1) A strong correlation except for some data (e.g. turbid conditions) between 500-m resolution MODIS chlorophyll-a (Chl.a) and in-situ Chl.a was observed (R=0.76, RE=15%). 2) Monthly Chl.a change pattern of 500-m resolution MODIS Chl.a and in-situ Chl.a in 2008 corresponded very well. 3) Chl.a in brackish Lake Shinji and Lake Nakaumi was convertible in T-P and T-N as well as these in the freshwater lakes. 4) Yearly average TSI of Lake Kasumigaura was the highest, and that of Lake Biwa was the lowest in six lakes. 5) High level TSI (Chl.a) that exceeded pattern III corresponding to Japanese environmental standards of T-P and T-N was estimated in Lake Kasumigaura and Lake Kojima. 6) There are three main problems for TSI monitoring using MODIS data in “accuracy of MODIS Chl.a”, “satellite sensor resolution”, and “system of the in-situ observation and vertical Chl.a modeling”. However, TSI using 500-m resolution MODIS was a very useful monitoring method for eutrophic lakes.
