Monitoring Volcanic Eruptions in Indonesia and the Southwest Pacific

We briefly describe current operational remote sensing at the Darwin Volcanic Ash Advisory Centre. The region has been particularly active during the second part of 2002, and we show GMS-5, NOAA/AVHRR-16, and Aqua/MODIS data from eruptions of Raung (Java, Indonesia), and Ruang (Sangihe Islands, Indonesia). We also show a possible ‘volcanic thunderstorm ’ from Rabaul, Papua New Guinea, in 1999. The higher spatial resolution of polar orbiting instruments is important for examination of eruption details and detection of small eruptions, but the high temporal resolution of geostationary satellites is critical for an effective warning service. The ‘split-window ’ method is the primary method of volcanic ash detection. GMS-5 can be effective at detecting ash with the split-window method, particularly in the eruption at Ruang. ‘False alarms ’ caused by the stratospheric temperature inversion and poor instrument calibration can be minimised with the enhancement techniques used in Darwin. The availability of more spectral bands in polar orbiting satellites can help us understand the nature of eruption clouds. The 0.415 µm reflective band on Aqua/MODIS observed the Ruang eruption distinctly, and the 1.6 µm band on NOAA-16/AVHRR clearly distinguished th