| description abstract | Devastating eruptions occurred at Manam, Papua New Guinea, from October 2004 to January 2005. An unprecedented set of pilot reports were obtained; ground-, air-, and satellite-observed eruption heights differed greatly. Satellite postanalysis and satellite CO2 slicing techniques give consistent heights. The climactic eruption, on 27 January 2005, reached 21?24 km MSL; four other eruptions reached 16.5?19 km. Tracking of these ice-rich clouds was done by monitoring strong ?ice? signatures on 11?12-?m infrared imagery (for two eruptions), by using reflectance-based techniques (during the daytime), and by using SO2 detection (available only in postanalysis). A remote lightning detection network could not detect the eruption clouds, despite detecting lightning from thunderstorms in the area. The eruptions appeared to enhance the nocturnal cycle of (ash contaminated) deep convection above the island, consistent with previous work on diurnal volcanic cumulonimbus at Mount Pinatubo. The communications and infrastructure challenges of the region strongly affected the performance of the volcanic ash warning system, but can be partially addressed with the development of appropriate strategies. A strategy of gradual advisory cessation at the end of each event generally worked well but failed where numerical modeling and satellite observation were insufficient. An aircraft apparently encountered SO2 from the cloud over Dili, Timor-Leste; no engine damage was reported, but no close inspection was made at the time. It is suggested that maintenance guidelines be developed to help clarify the risk of volcanic ash damage from encounters with clouds where only SO2 odor is observed. | |
