Air quality « CIMSS Satellite Blog

Blowing dust in New Mexico, Texas, and Oklahoma

January 22nd, 2012

GOES-15 0.63 µm visible channel images (click image to play animation)

A large outbreak of blowing dust developed in the wake of a cold frontal passage across parts of New Mexico, Texas, and Oklahoma on 22 January 2012. At Lubbock, Texas winds gusted to 60 mph, and surface visibility was reduced to 0.5 mile. The strongest wind gust was 77 mph, farther to the north in the Texas panhandle region (NWS Lubbock summary). Early in the day, the consolidation of numerous smaller blowing dust plumes into a single large blowing dust “cloud” could be seen on 1-km resolution GOES-15 (GOES-West) 0.63 µm visible channel images (above; click image to play animation).

Later in the day, due to a more favorable forward scattering angle, the areal extent of the airborne blowing dust could be better seen on 1-km resolution 0.63 µm visible channel images from the GOES-13 (GOES-East) satellite (below; click image to play animation). The leading edge of the primary large dust plume began to move northeastward over Oklahoma, while a number of smaller dust plumes could be seen moving southeastward across the Oklahoma and Texas panhandle regions behind a secondary cold front. Note that the GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5-10 minutes.

GOES-13 0.63 µm visible channel images (click image to play animation)

A 250-meter resolution MODIS true color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below, viewed using Google Earth) displayed even greater detail in the structure of the blowig dust plume at 20:02 UTC.

Aqua MODIS true color Red/Green/Blue (RGB) image (displayed using Google Earth)

There was also a bit of smoke mixed in with the blowing dust, due to a few small wildfires that were burning across the region. Three small wildfire “hot spots” (dark black to yellow pixels) could be seen on an AWIPS image of 1-km resolution MODIS 3.7 µm shortwave IR data at 20:00 UTC (below).

MODIS 3.7 µm shortwave IR image

Over southern Oklahoma at 21:23 UTC a pilot reported that at an altitude of 9000 feet the flight level visibility was zero due to blowing dust (below).

GOES-13 0.63 µm visible channel image + Aircraft pilot report

Posted in Air quality, Aviation, Fire detection, GOES-13, GOES-15, Google Earth, MODIS, Red/Green/Blue (RGB) images | No Comments »

Blowing dust in west Texas

November 26th, 2011

GOES-13 0.63 µm visible channel images

Strong northerly winds in the wake of a cold frontal passsage caused widespread blowing dust across parts of west Texas during the afternoon hours on 26 November 2011. The hazy plumes of blowing dust could be seen on GOES-13 0.63 µm visible channel images (above). At Midland, Texas (located near the center of the images) the winds gusted to 51 mph, and surface visibility was reduced to 0.5 mile at times.

After sunset, when visible imagery was no longer available, the southward progress of the airborne dust could still be tracked using a GOES-11 IR difference product (below), created by subtracting the 12.0 µm IR brightness temperature from the 10.7 µm IR brightness temperature. The larger IR difference values (around 2-3 degrees Kelvin, yellow color enhancement) represented the portions of the airborne dust cloud that were the most concentrated.

GOES-11 0.65 µm visible images + GOES-11 IR difference product images

It is important to note that GOES-11 (GOES-West) is the only remaining operational GOES satellite that still has the 4-km resolution 12.0 µm IR channel on the Imager instrument (a 10-km resolution 12.0 µm channel is still on the Sounder instrument on all GOES satellites) — and GOES-11 will soon be replaced by GOES-15 on 06 December 2011. After that time, using such an IR difference product to track areas of blowing dust will have to be done using polar orbiting satellites (such as POES, MODIS, or NPP) or the GOES Sounder that still have the 12.0 µm IR channel.

Posted in Air quality, GOES-11, GOES-13 | No Comments »

Caughlin Wildfire near Reno, Nevada

November 18th, 2011

GOES-15 3.9 µm shortwave IR images (click image to play animation)

The 2000-acre “Caughlin Fire” started burning around 08:45 UTC (1:45 am local time) in the hilly terrain near Reno, Nevada, and soon grew out of control due to strong winds gusting as high as 74 mph. McIDAS images of GOES-15 3.9 µm shortwave IR data (above) showed the “hot spot” (black to yellow to red enhanced pixels) associated with the fire. At least 30 homes were destroyed, with many more damaged by the fire. Thousands of residents were evacuated.

Evidence of the strong winds across the region could be seen on an AWIPS image of MODIS 6.7 µm water vapor channel data (below), with a number of very pronounced mountain waves showing up on the image. These mountain waves persisted for several hours, and were responsible for pilot reports of severe turbulence, wind shear, and 50-knot crosswinds during descent to final approach into the Reno airport. The highest wind gust reported at the Reno airport was 44 mph, and surface visibility was also reduced to 6 miles at the airport due to smoke.