Chile is one of the most volcanically active countries on Earth. The latest volcano to erupt is Chaiten, which had previously lain dormant for at least 1000 years. Chaiten is at approximately 42 degrees South latitude, 72 degrees west longitude, close to Golfo de Ancud. A series of eruptions, starting on May 2, has prompted the evacuation of Chaiten, a provincial capital with a population of 4000.

GOES-10 captured the plume of an eruption that started near 12 UTC on 6 May. Volcanic ash does not have an emissivity of 1; that is, it does not emit as a blackbody. The emissivity at 10.7 microns is smaller than the emissivity at 12 microns. The smaller signal received at 10.7 microns (relative to the assumed blackbody) is interpreted as a cooler emitting surface. If the blackbody temperatures at 10.7 and 12.0 microns are compared, then, values at 12.0 microns are warmer. A channel difference can be used to highlight the horizontal extent of the volcanic ash. In the loop shown, the bluest pixels correspond to a blackbody temperature difference of nearly 10 K. That is, the 12 micron blackbody temperature is 10 K warmer than the 11 micron blackbody temperature. The remnants of an older eruption are also noted near the Atlantic Coast of Argentina.

A sequence of GOES-10 imager and sounder IR difference products during the 02-08 May period (below) shows evidence of plumes from multiple eruptions of the Chaiten Volcano. The GOES-10 Imager can provide nearly continuous (15 minute) coverage of the evolving ash cloud, while the GOES-10 Sounder can provide details on the upper-level SO2 plumes once every four hours. The former is derived utilizing the 11.0 micrometer and 12.0 micrometer bands from the Imager. SO2 plumes are revealed by differencing the 7.4 micrometer and 13.3 micrometer bands from the Sounder.

Click here to see an animated gif every from every four hours — that is, each hour for when sounder data are available.

An AVHRR false color image from 05 May (below, viewed using Google Earth) revealed a long plume from the Chaiten volcano, which stretched eastward across Argentina and then southeastward over the South Atlantic Ocean.

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AWIPS images of the GOES-12 6.5 µm “water vapor” channel (above) showed the development of late-season winter storm that produced heavy snowfall and blizzard conditions (with wind gusts to 64 mph or 29 m s-1 at Rapid City SD) across the Black Hills region and surrounding portions of eastern Wyoming, southeastern Montana, and western South Dakota during the 30 April through 02 May 2008 period. A closer view using GOES-12 10.7 µm IR images reveals that there were a number of cloud-to-ground lightning strikes during various phases of the storm’s development, as large convective elements formed and intensified upwind of the Black Hills.

A MODIS true color image (above, viewed using Google Earth) shows the areal extent of the snow cover on 03 May 2008, as well as the locations of the heaviest total snowfall amounts: 54.5 inches (138 cm) at Lead SD, and 24.0 inches (61 cm) at Sundance WY.

A comparison of MODIS true color and false color images from 03 May (above) demonstrates how the false color imagery (which uses the MODIS 2.1 µm near-IR channel) can differentiate between snow cover (which, along with ice crystal clouds and ice-covered lakes, appear as cyan-colored features) and supercooled water droplet clouds (which appear as shades of white).

Consecutive daily MODIS false color images from 02, 03, and 04 May (below) show that the snow cover was melting rapidly under the influence of the strong May sun. The 54.5 inches of snow that fell at Lead SD had a liquid equivalent of 4.64 inches (12 cm), so the rapid snowmelt led to a quick rise of creeks and streams that caused some flooding problems.

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Category 4 intensity Cyclone Nargis made landfall across southern Myanmar (formerly known as Burma) late in the day on 02 May 2008, packing maximum winds around 135 mph (60 m s-1), producing a storm surge of 12 feet (3.6 meters), and dumping nearly 20 inches (51 cm) of rainfall. According to media reports, the estimated death toll from this powerful tropical cyclone ranges from 22,000 to nearly 100,000. AVHRR false color images from 01 and 02 May (above, viewed using Google Earth) showed Cyclone Nargis in the Bay of Bengal, moving eastward toward Myanmar.

An animation of the Morphed Integrated Microwave Imagery at CIMSS (MIMIC) product (below) revealed evidence of a double eyewall, suggesting that Cyclone Nargis was going through an eyewall replacement cycle just prior to and near the time of landfall.

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GOES-12 RGB composite images (above, using the visible and 3.9 µm shortwave IR channels) revealed a cluster of “hot spots” (red-enhanced pixels) and a large smoke plume drifting east/northeastward from a large grass fire located about 30 miles southeast of Fort Stockton, Texas on 01 May 2008. This fire — known as the Huckabee Fire — started on 30 April (due to a downed power line), and eventually ended up burning over 96,000 acres. This large and very hot fire saturated the 3.9 µm shortwave IR detectors on GOES-12, with the imagery indicating a maximum IR brightness temperature of 337.4º K (64.3º C or 147.7º F).

AWIPS images of the GOES-12 3.9 µm shortwave IR channel (below) showed that the Huckabee fire continued to burn into the morning hours of 02 May, as a cold front moved southward across the region — the cooler air behind the cold frontal boundary was evident as lighter shades of gray surging southward, while warmer, more humid air appeared as darker shades of gray moving slowly northward across eastern Texas into Oklahoma (in advance of the approaching cold front).

An AWIPS 4-panel comparison of MODIS and GOES-12 “shortwave IR” and “IR window” channel data (below) showed the cluster of hot pixels around 09 UTC (4 am local time) on 02 May. This large fire was so hot that a “hot spot” was even apparent on the IR window channel images — surprisingly, the brightness temperature of the hot spot on the GOES-12 IR window image was higher (as indicated by the single yellow-enhanced pixel in the lower right panel) than on the corresponding MODIS IR window image (the cluster of black pixels in the upper right panel).

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