Satellite observations of Mt Pinatubo ash clouds

Satellite imagery currently available from the Japanese Geostationary Meteorological Satellite (GMS) is of great benefit to operational meteorologists responsible for the provision of warnings for volcanic ash clouds for aviation in the Asian region. However, on visible and single channel infrared satellite data it is frequently not possible to discriminate volcanic ash clouds from water/ice clouds. This is a particular problem in the volcanically active southeast Asian region where there is a high frequency of thunderstorms which can produce extensive areas of cloud. It has previously been demonstrated that National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) satellite data can be used to improve the discrimination of volcanic ash clouds from water/ice clouds. This is based on identification of areas where the brightness temperature difference, T(10.8 µm)-T(ll.9 µm), is negative. In a study of GMS and AVHRR satellite data for the Mt Pinatubo eruptions of 12 June 1991 this paper confirms the operational availability of AVHRR data should enable a significant improvement in our ability to identify volcanic ash clouds.