*********************** Merapi Volcano Imaged *********************** From: Michael Ramsey <ramsey@xxxxxxxxxxxxxxxxx> FYI, Merapi Volcano, Indonesia was imaged on two different opportunities recently by the ASTER spaceborne instrument following a special observation request. A daytime image (15m/pixel) was collected on 26 April 2006 at 03:05 UTC and a night time thermal infrared (TIR) image (90m/pixel) was collected on 28 April 2006 at 15:10 UTC. The daytime image shows a minor plume, however most of the summit is obscured by a small cloud. The nighttime image shows a clear summit with obvious (albeit low-grade) thermally-elevated pixels (max = 25.9 C). These pixels are clustered near the summit with a lesser anomaly (max = 15.5 C) approximately 650m to the southwest and down slope from the summit. A processed image of both acquisitions has been posted here: http://ivis.eps.pitt.edu/data/04-2006_merapi.jpg Temperatures extracted from ASTER TIR pixels are averages over the entire 90m pixel. Examination of the TIR emissivity for the hottest pixels shows evidence of thermal heterogeneities below the scale of the pixel (on the order of 100's degrees C over <5% of the pixel). This thermal elevation is also seen in the 2.33 micrometer shortwave infrared (SWIR) image (30 m/pixel resolution) collected at the same time as the nighttime TIR data. A very weak thermal anomaly at the summit in several of the pixels indicates a maximum temperature of no more than ~200 C (averaged over the 30 m pixels). For more information about the ASTER instrument and its specifications, please see: http://asterweb.jpl.nasa.gov/ Cheers, Michael Ramsey ASTER Science Team ============================================================== 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. ==============================================================
