Satellite data are an important source of information in the provision of warnings about volcanic ash for the aviation industry. However, the operational utility of these data continues to be limited by difficulties in discriminating ash from water/ice clouds. The brightness temperature difference between the NOAA AVHRR water vapour window channels at 10.8 and 12 micron has proved beneficial for discriminating ash but these data are available less frequently than operationally desirable. Over the Asia-Pacific region the Japanese geostationary meteorological satellite GMS-5, which became operational in 1996, provides hourly data in two infrared channels in the water vapour window, similar to the NOAA AVHRR sensor. In this paper we will examine both the GMS-5 and AVHRR data for the New Zealand Mt Ruapehu eruption of 19 July 1996. We show the GMS-5 IR1-IR2 data displays characteristic differences for ash and water/ice clouds similar that evident in AVHRR imagery though less well defined because of the reduced spatial and temperature resolution. The hourly GMS-5 data enables the more timely detection of ash clouds and the movement to be better monitored.
The 8th Conference on Aviation, Range, and Aerospace Meteorology