GOES-12 10.7 µm IR images + cloud-to-ground lightning strikes

Strong convection moving eastward from Florida and across the Bahamas produced at least two tornadoes on the island of Grand Bahama on 29 March 2010 — according to media reports, there were fatalities at the Grand Bahama Container Port located at the western end of the island, where several large cranes were toppled. There were also tornadoes reported in Florida a few hours earlier. AWIPS images of GOES-12 10.7 µm IR channel data with an overlay of negative (cyan) and positive (violet) cloud-to-ground lightning strikes (above; also available as a QuickTime animation) showed several clusters of convection moving across Grand Bahama Island (located in the center of the images; station identifier MYGF is Freeport). In particular, note the storms with the highest density of negative cloud-to-ground lightning strikes moving across the island during the 15:15 – 15:45 UTC time period — this is likely the convective cell that produced the tornadoes. The coldest IR brightness temperatures over the Bahamas on the 4-km resolution GOES-12 images was -66º C (darker red color enhancement).

The Blended Total Precipitable Water (TPW) product (below) indicated that TPW values were in excess of 50 mm or 2.0 inches (darker purple color enhancement) along and ahead of a cold frontal boundary that was approaching from the west. These TPW values were 150%-200% above normal. In addition, the presence of a pre-frontal trough may have played a role in helping to enhance surface convergence in the vicinity of the Bahamas.

Blended Total Precipitable Water product

A closer view using 1-km resolution MODIS 11.0 µm IR channel data at 15:52 UTC (below) revealed greater detail in the overshooting top structure of the convection as it was moving over the eastern portion of the Grand Bahama Island. The coldest MODIS IR brightness temperatures near the island were -70º C (black color enhancement).

MODIS 11.0 µm IR image

The CLAVR-x POES AVHRR Cloud Type product (below) indicated a number of “Overshooting Top” category clouds (violet color enhancement) associated with the stronger convective clusters.

POES AVHRR Cloud Type product

The POES AVHRR Cloud Top Height product (below) showed that the highest cloud tops over the Bahamas were around 15 km or 49,000 feet (cyan color enhancement).

POES AVHRR Cloud Top Height product

A MODIS Sea Surface Temperature (SST) product from the following day (below) revealed that there was a very strong SST gradient between Florida (where SST values were primarily in the mid 60s F, green colors) and the Bahamas (where SST values were in the mid 70s F, orange colors). Perhaps the significantly warmer SST values of the Gulf Stream may have also played a role in the intensification of the convection as it approached the Bahamas?

MODIS Sea Surface Temperature product

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GOES-12 visible images

McIDAS images of the GOES-12 0.65 µm visible channel data (above) showed the development of a large plume of blowing dust across parts of southern New Mexico and western Texas late in the day on 26 March 2010. Surface winds gusted to 84 mph at El Paso in Texas, with the blowing dust temporarily reducing the surface visibility to 0.1 mile.

A 250-meter resolution Aqua MODIS true color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below) revealed that at the time of the Aqua satellite overpass (20:24 UTC), plumes of blowing sand were already beginning to stream northeastward from the White Sands National Monument and Missile Range in southern New Mexico — the blowing sand had already reached the partially snow-covered Sacramento Mountains located to the east of Alamogordo. At that time, the surface visibility at Alamogordo was 5 miles…but within 3 hours the visibility there dropped to 0.5 mile.

Aqua MODIS true color image (viewed using Google Earth)

With the approach of darkness, the GOES-12 (GOES East) visible channel imagery could no longer be utilized to track the location and movement of the thick airborne dust — however, the older GOES-11 (GOES West) satellite imager instrument still retains a 12.0 µm channel that is helpful for creating a simple 10.7 – 12.0 µm (channel 04 – channel 05) IR temperature difference product that is useful for tracking airborne dust (and also volcanic ash) at night. Such a sequence of GOES-11 10.7 – 12.0 µm images (below) showed that the dust plume (yellow to cyan color enhancement) continued to move eastward and northeastward across Texas and into southwestern Oklahoma during the hours after sunset.

GOES-11 10.7-12.0 µm IR temperature difference images

A few hours later, a similar MODIS IR difference product created by subtracting the brightness temperatures of the 11.0 µm and 12.0 µm channels (below) showed that the leading edge of the dust (yellow color enhancement) had moved as far as northern Oklahoma and extreme southern Kansas. Note the “cleaner” appearance of the MODIS IR difference product, a result of the higher spatial resolution (1 km) and improved spectral response of the IR channels on the MODIS instrument compared to the GOES imager.

Aqua MODIS 11.0-12.0 µm IR temperature difference product

The ABI instrument aboard the GOES-R satellite will mark the return of the 12.0 µm channel on the GOES imager, which will allow such phenomena to be more easily identified and tracked.

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MODIS true color and false color images

A comparison of 250-meter resolution MODIS true color and false color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above) showed a large fire (perhaps a prescribed burn?) in a remote area of the Red Lake Indian Reservation, just to the west of the Upper and Lower Red Lakes in far northern Minnesota on 26 March 2010. On the false color RGB image, the fire hot spot shows up as a large bright red feature — note the rapid increase in areal coverage of the burn area between the time of the 17:04 UTC Terra satellite overpass and the 18:50 UTC Aqua satellite overpass. The still-frozen lakes appear as varying shades of cyan, while unfrozen bodies of water show up as a much darker blue color. On the true color RGB image, the hazy-looking smoke plume can be seen drifting northward (advected by surface winds from the south that were gusting as high as 29 knots).

MODIS 3.7 µm, POES AVHRR 3.7 µm, and GOES-12 3.9 µm shortwave IR images

AWIPS images of the 1-km resolution MODIS 3.7 µm, the 1-km resolution POES AVHRR 3.7 µm, and the 4-km resolution GOES-12 3.9 µm shortwave IR channel data (above) shows some important differences in both the location of the hottest pixels (GOES-12 has the fire located farther to the west, in far eastern Pennington county) as well as the intensity of the hot spots: the 18:42 UTC MODIS image registered a maximum IR brightness temperature value of 46.5º C, and the 18:48 UTC POES AVHRR image registered a value as high as 54.5º C. At that same time, the cursor readout for the 18:45 UTC GOES-12 image read “NO DATA” — thus demonstrating the value of the 1-km resolution MODIS and POES AVHRR imagery for identifying the exact location of the hottest portion of the fire.

An animation of the 4-km resolution GOES-12 3.9 µm shortwave IR images (below) did show that the fire hot spot was gradually growing in size, and briefly began to exhibit IR brightness temperature values as high as 37.5º C at 17:45 UTC and 48.0º C at 18:15 UTC — but then the fire intensity exceeded the AWIPS temperature threshold and “NO DATA” was indicated by the AWIPS cursor readout before the fire hot spot eventually became obscured by a dense cirrus cloud canopy drifting overhead from the southwest..

GOES-12 3.9 µm shortwave IR images

The shortwave IR channels on the ABI instrument aboard the GOES-R satellite will have a spatial resolution of 2 km, which should produce images that more closely resemble the 1-km resolution MODIS and POES AVHRR images shown above (further enhancing our fire detection capabilities in the future).

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NOAA-19 AVHRR 3.7 µm shortwave IR image

The Eyjafjallajökull volcano in southern Iceland (which had last erupted in the 1820s) experienced a minor eruption on 21 March 2010. An AVHRR 3.7 µm shortwave IR image from the polar-orbiting NOAA-19 satellite (above) showed evidence of a “hot spot” (black to yellow pixels) due to the resulting lava flows.

According to the London VAAC, the volcanic eruption did not produce significant volcanic ash above the 5000 foot level:

FVXX01 EGRR 211458
VA ADVISORY
DTG: 20100321/1200Z
VAAC: LONDON
VOLCANO: EYJAFJOLL
PSN: N6339 W01926
AREA: ICELAND
SUMMIT ELEV: 1000M
ADVISORY NR: 2010/006
INFO SOURCE: ICELAND MET OFFICE
AVIATION COLOUR CODE: UNKNOWN
ERUPTION DETAILS: ERUPTION CONTINUES
OBS VA DTG: 21/1200Z
OBS VA CLD: SFC/FL050 N6331 W01923-N6559 W02252-N6559 W03252-N6047 W03823-N6017 W0342 -N6331 W01923
FCST VA CLD +6HR: 21/1800Z SFC/FL050 N6331 W01919-N6705 W02525-N6704 W03621-N5801 W04323-N5633 W03545-N6143 W03035-N6331 W01919
FCST VA CLD +12HR: 22/0000Z SFC/FL050 N6331 W01903-N6750 W02833-N6750 W03955-N6131 W04520-N5435 W04459-N5501 W03207-N5954 W03105-N6331 W01903
FCST VA CLD +18HR: 22/0600Z SFC/FL050 N6342 W01929-N6838 W03232-N6808 W04515-N5426 W04601-N5202 W03737-N5644 W02954-N6143 W03247-N6342 W01929
RMK: THIS ADVISORY SUPERCEDES ADVISORY 2010/005. VOLCANIC ASH NOT ABOVE FL050, ERUPTION MAINLY LAVA
NXT ADVISORY: 20100321/1800Z=

Aqua MODIS 3.7 µm shortwave IR image

The minor volcanic eruptions continued for several days; meteorological clouds often obscured Iceland during that time, but on 24 March an overpass of NASA’s Aqua satellite allowed another view of the lava flow “hot spot” (red pixels) on a 1-km resolution MODIS 3.7 µm shortwave IR image (above). The maximum IR brightness temperatures within the red pixel area were 330 K. Additional photos and video have been posted by the Icelandic Met Office.

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