********************************* Merapi Volcano Imaging continues ********************************* From: Michael Ramsey <ramsey@xxxxxxxxxxxxxxxxx> In an email posted to the Listserv 2 weeks ago, I mentioned that the joint NASA-Japanese imaging instrument known as ASTER observed Merapi Volcano. For more information about the ASTER instrument and its specifications, please see: http://asterweb.jpl.nasa.gov/ On the previous overpass, ASTER recorded minor anomalies (max = 25.9 C) observed using data from its thermal infrared (TIR) subsystem (8-12 micrometers). Temperatures extracted from ASTER TIR pixels are averages over the entire 90m pixel. ASTER also images the surface at 30 m/pixel resolution in the short-wave (SWIR) infrared region (2.0 - 2.5 micrometers). Pixel integrated temperatures from ~ 200-500 C emit energy in this region. Two weeks ago the ASTER SWIR data had a very minor SWIR temperature anomaly. New ASTER daytime data were collected on 12 May at 03:05 (UTC) and have a much stronger thermally anomaly consistent with local observations of increasing activity. The SWIR data show a region of ~ 150m x 240m of thermally-elevated pixels centered at the summit dome. The maximum derived temperature was 213 C, however this is integrated over 30 square meters and temperatures locally could be much higher. This is also confirmed by examination of the emissivity spectra collected in the TIR region. A processed image of the SWIR-derived temperatures over the visible/near infrared (VNIR) image of the summit has been posted here: http://ivis.eps.pitt.edu/data/12May06.pdf A weak diffuse plume was also observed drifting to the NE. Visible and thermal coloration of the plume indicate the presence of SO2, but no estimation of volume has been made. ASTER will continue to monitor Merapi using both day and night time observations while the current heightened activity continues. Cheers, Mike Ramsey ++++++++++++++++++++++++++++++++++++++++++++++++++++++ Dr. Michael Ramsey, Associate Professor Department of Geology & Planetary Science (200 SRCC Building) University of Pittsburgh; Pittsburgh, PA 15260-3332 office: 412-624-8772; fax: 412-624-3914 IVIS lab: 412-624-8773, spec 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. ==============================================================
