AWIPS 4-panel GOES imagery (IR, visible, water vapor channels)

The GOES-12 satellite (the operational GOES-East satellite) suffered a Thruster 2B oxidizer leak around 22:00 UTC on 14 December 2008, which caused the suspension of GOES-12 Imager and Sounder data. For several hours following the GOES-12 thruster anomaly, GOES-11 (the operational GOES-West satellite) was placed into Full-Disk mode to provide coverage as far east as possible. AWIPS 4-panel GOES images (above) show that the image quality was adversely impacted over the far eastern US and Canada during that time, due to the very large viewing angle from GOES-11 (which is positioned at 135º W longitude). Also, note that the water vapor channel imagery (lower right panel) was not available in AWIPS during the time that GOES-11 IR imagery (upper 2 panels) was filling in for the missing GOES-12 data — and of course, there was no visible channel data (lower left panel) since it was night-time.

However, the GOES-13 satellite — which had been in an extended period of on-orbit storage at 105º W longitude — had been activated in early August of 2008, so it could very quickly be utilized to replace GOES-12. As of 12:30 UTC on 15 December, GOES-13 data began to replace GOES-12 data as the GOES-East satellite data source for AWIPS, which then allowed  the image quality over the far eastern US and Canada to return to normal. The channels on the GOES-13 Imager and Sounder are identical to those on GOES-12 (including the 4-km resolution water vapor channel) — however, the primary improvements with GOES-13 are better image navigation, and larger on-board batteries to allow the satellite to operation through Spring and Fall eclipse periods (when the satellite is in the Earth’s shadow, and the solar panels cannot provide power to the spacecraft instruments).

For the latest information, see the NOAA Satellite Services Division Special Bulletins.

Note: GOES-13 data is being re-broadcast through GOES-12, so users with GOES East direct broadcast ground stations do not need to adjust their antennas.

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MODIS visible, cirrus, 3.7 µm IR, and water vapor images

Strong winds were producing plumes of blowing dust across parts of southeastern New Mexico and the  Texas panhandle region on 14 December 2008 — this blowing dust was reducing surface visibility to 1 mile at Lubbock, Texas (station identifier KLBB). AWIPS images of the MODIS visible, “cirrus detection”, 3.7 µm shortwave IR, and 6.7 µm water vapor channels (above) showed the plumes around 19:51 UTC. The plumes of airborne aerosols exhibited a lighter gray “hazy” appearance on the visible image (and to a lesser extent on the “cirrus detection” image, due to that channel’s sensitivity to particles that scatter light).

In addition, there was a small cluster of hot MODIS 3.7 µm IR pixels with a maximum temperature of 46º C located just northwest of Hobbs, New Mexico (station identifier KHOB), due to a grass fire that was burning in that area (MODIS 3.7 µm image) — and 250-meter resolution MODIS true color imagery (below) confirmed the presence of a lighter-colored smoke plume embedded within the longer orange-colored blowing dust plume. The burn scar from this fire was clearly evident on MODIS true color imagery (viewed using Google Earth) on the following day (located between Lovington and Maljamar, New Mexico).

MODIS true color image

The strong winds (which gusted as high as 71 mph at Tatum, New Mexico) were producing mountain waves immediately downwind of the higher terrain in the “Big Bend region” of Texas — a comparison of 1-km resolution MODIS 6.7 µm and 4-km resolution GOES-12 6.5 µm water vapor images (below) demonstrated the value of better spatial resolution for detecting such mesoscale phenomena.

MODIS 6.7 µm and GOES-12 6.5 µm water vapor images

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MODIS visible and "snow/ice channel" images

A major ice storm impacted much of the Northeast US on 11 December – 12 December 2008 — many locations across that region experienced several hours of freezing rain, leading to widespread ice accumulations of 0.5 to 1.0 inch which brought down tree limbs and power lines (causing power outages for an estimated 1 million customers). After the storm, AWIPS images of the MODIS visible and near-IR “snow/ice” channel from the morning of 13 December 2008 (above) offered some clues as to the areal coverage of the more significant ice accrual. Since snow and ice are strong absorbers of radiation at the near-IR 2.1 µm wavelength,  the darkest areas on the snow/ice image are areas where the thickest accrual of ice occurred (although lakes and other bodies of water also appear as dark black features). Note that some of the darker ice-covered areas on the snow/ice image do not look as “bright” on the visible image as adjacent areas with deeper snow cover, since the ice (without a layer of snow on top) is generally more “translucent” or light gray in appearance than the brighter white snow cover.

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GOES-12 6.5 µm water vapor images

An unusually-early snowfall event occurred in parts of Louisiana and Mississippi on 11 December 2008. AWIPS images of GOES-12 6.5 µm water vapor images (above) revealed a well-defined axis of a deformation zone pivoting over the region that received the heaviest snowfall. The GOES sounder Total Column Ozone product (below) showed values in the 350-400 Dobson Unit range (bright green to red colors), indicative of the lowering dynamic tropopause associated with the intensifying disturbance.

GOES sounder Total Column Ozone product

MODIS visible, 11.0 µm IR, and 6.7 µm water vapor images at 19:19 UTC (below) showed a narrow banding structure in place over the area where moderate to heavy snowfall was falling at the time.

MODIS visible, 11.0 µm IR, and 6.7 µm water vapor images

SSEC MODIS Today true color imagery from the following day (below, displayed using Google Earth) displayed a large area where snow remained on the ground. The highest snowfall accumulations included 9 inches at New Hebron in Mississippi and 8 inches at Amite in Louisiana. For locations such as Beaumont/Port Arthur in Texas and Lake Charles, Baton Rouge and New Orleans in Louisiana, this was the earliest snowfall on record.

MODIS true color image on 12 December (displayed using Google Earth)

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