****************************************** ASTER imaging of Merapi Volcano continues ****************************************** From: Michael Ramsey <mramsey+@xxxxxxxx> The ASTER instrument is continuing to collect data of Merapi Volcano, Indonesia in an urgent request mode. Following Saturday's deadly 6.3-magnitude quake, ASTER observations were scheduled for Sunday, 28 May (daytime observation) and Tuesday, 30 May (nighttime observation). Unfortunately, the daytime observation was hampered by heavy cloud cover around the volcano. The very summit of the volcano did show a thermally-elevated region, however the derived temperatures were no greater than 200 C. This is much lower than the previously clear ASTER observation (14 May), which had temperatures in excess of 425 C at the summit. It is likely that the summit was partially covered during the 28 May observation by thin clouds/plume, which obscured the true surface temperature. The nighttime image just acquired on 30 May is 100% clear and shows a dramatic rise in temperatures at the summit. The maximum derived temperature was 447 C, with 11 short wave infrared (SWIR) pixels (9,900 m^2) in excess of 400 C. This is the hottest and largest area seen so far with ASTER. Two distinct zones of thermally-elevated pixels are evident: the first extends slightly over 2 kilometers down slope to the SW following the path of previous PF's deposits; the second extends approximately 600 meters down slope to the SE. A third circular region of thermally-elevated pixels lies between the other two, is approximately 10,000 m^2 in area, and presumably corresponds to the dome. The SWIR-derived temperatures have been countered and overlain on the coincident TIR temperature image (90m/pixel resolution). The image can be found here: http://ivis.eps.pitt.edu/data/merapi/30May06_1.pdf The TIR data have also been processed using a decorrelation stretch technique used to highlight compositional variation on the summit and plume. The stretch used ASTER bands 14, 13, 11 in red, green, blue (respectively) and shows a diffuse blue plume extending to the NW (denoted by a black arrow). This color combination indicates that very little ash or SO2 is present in the plume at the time. The plume is likely dominated by water/ice. The image is located here: http://ivis.eps.pitt.edu/data/merapi/30May06_2.pdf ASTER will continue to observe Merapi during the crisis period. The instrument is unique for volcanic observations because of its 15m - 90m spatial resolution, its ability to be scheduled and point off-nadir, and its ability to collect visible to thermal IR data during both the day and night. For more information on ASTER, please see the NASA website for the instrument: http://asterweb.jpl.nasa.gov/ Cheers, Mike +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Dr. Michael Ramsey, Associate Professor Dept. of Geology & Planetary Science, University of Pittsburgh 4107 O'Hara Street, room 200 SRCC Pittsburgh, PA 15260-3332, USA office: 412-624-8772; fax: 412-624-3914; IVIS Lab: 412-624-8773, IVIS Spectrometer Lab: 412-624-7874 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
