NOAA-AVHRR imagery of volcanic clouds in Kyushu, Japan

Volcanic clouds in Kyushu, Japan were found in 54 data sets of NOAA-AVHRR between March 1990 and March 1991 among 97 sets. Most of the clouds were emitted from Mt. Sakurajima with various scales up to a few hundred km in length, while several samples of them from Mt. Aso and Mt. Unzen were found with lengths up to 20 km. The bispectral method used the difference between the brightness temperatures of AVHRR channels 4 and 5 and was able in many cases to discriminate volcanic clouds from water/ice clouds.<
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