抄録
What a kind of merit can be expected for the use of unclassified photo reconnaissance satellite images released in 1995? Such image data had been taken from 1960 to 1972 by the American KH-4/CORONA and KH-7/GAMBIT etc. The total number of the photographs is said to reach more than 800,000 sheets. Making a comparison of the recent satellite images with such old images at the same area, land cover change or some environmental phenomena can be detected. A case study was made to know the capability of the old images at two test sites, Yokohama area including Keihin industrial zone and Totsuka suburban area about 40 km from Central Tokyo southeast. The following results are obtained.
(i) Unclassified reconnaissance satellite images show us the environmental change in 1960s as evidence.
(ii) Those images show the discharged heavy plumes in the industrial area. The satellite images record the actual phenomena at those days.
(iii) More classified satellite images should be released as earlier as possible for any study in the area of non-security.
