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

McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed the smoke plume emanating from a large fire that was burning in the Okefenokee Swamp in far southern Georgia on 06 May 2011. This fire originally began on 28 April as a result of a cloud-to-ground lightning strike.

AWIPS images of GOES-13 3.9 µm shortwave IR data (below; click image to play animation) displayed the rapid growth in size of the associated fire “hot spot” (black to red to yellow color enhancement). The hot spot first became apparent around 17:31 UTC (1:31 pm local time), and quickly grew as drier air moved across the region in the wake of a passing cold frontal boundary.

GOES-13 3.9 µm shortwave IR images (click image to play animation)

A comparison of AWIPS images of 1-km resolution POES AVHRR 3.7 µm and 4-km resolution GOES-13 3.9 µm shortwave IR data (below) demonstrated the advantage of better spatial resolution for locating the fire boundaries. CIMSS participation in GOES-R Proving Ground activities includes making a variety of POES AVHRR images and products available for National Weather Service offices to add to their local AWIPS workstations. A “POES and AVHRR Satellite Products in AWIPS” VISIT training lesson is also available to help users understand the products and their applications to weather analysis and forecasting.

POES AVHRR 3.7 µm + GOES-13 3.9 µm shortwave IR image comparison

===== 07 MAY UPDATE =====

On the following day, a comparison of 250-meter resolution MODIS true color and false color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) revealed the dense smoke plume (which appeared as varying shades of  gray on the true color image), as well as the large size of the burn scar (which appeared as darker shades of darker red to brown on the false color image) resulting from this fire that had been burning for several days. Also evident was the fact that several active, very hot fires were burning at this time along the edges of the burn scar — these hot fires appeared as the brighter pink areas on the false color image. Many of these fire “hot spots” could even be detected through the dense smoke.

MODIS true color and false color images

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MODIS 0.65 µm visible channel image + MODIS 2.1 µm near-IR "snow/ice channel" image

A comparison of AWIPS images of the 1-km resolution MODIS 0.65 µm visible channel (first shown with a map overlay and location of METAR sites) and the corresponding 1-km resolution MODIS 2.1 µm near-IR “snow/ice channel” (above) shows the areal coverage of flood waters across the region of the confluence of the Mississippi River and the Ohio River on 04 May 2011. Since water happens to be a strong absorber at the 2.1 µm wavelength, it shows up as a very dark feature on the MODIS “snow/ice channel” image — making it more useful for locating areas of flooding than just a simple visible channel image.

A similar near-IR channel will be on the ABI instrument of the future GOES-R satellite. CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS images and products available for National Weather Service offices to add to their local AWIPS workstations.

MODIS True-color imagery from the SSEC MODIS Today website can be used to compare data from this year and last year, shown below. In the linked-to-images, the Mississippi River north of Memphis (located at the bottom edge of each image) meanders through the center part of the images. There are several former meanders of the river in Arkansas and Tennessee that are filled with water this year, but not last.

MODIS true color images (04 May 2010 and 04 May 2011)

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MODIS 0.65 µm visible channel images

A late-season blizzard produced as much as 14.0 inches of snowfall with winds gusting as high as 78 mph across western North Dakota (and 10.0 inches of snowfall across extreme eastern Montana) on 30 April 2011, causing power outages and the closure of Interstate 94 from Dickinson to the Montana border. On the following day (01 May 2011), AWIPS images of MODIS 0.65 µm visible channel data (above) displayed a mixture of fresh snow cover and cloudiness across parts of western North Dakota, far southeastern Saskatchewan, and southwestern Manitoba. However, in some areas it was difficult to visually separate the cloud features from the snow cover (although the edges of the snow pack that were quickly melting within the 102-minute time period between the 2 MODIS images were fairly obvious).

The corresponding pair of MODIS false color Red/Green/Blue (RGB) images (below) — created using MODIS bands 01/07/07 — allowed for the unambiguous discrimination between the fresh snow cover (which appeared darker red) and the various cloud features (supercooled water droplet clouds exhibited a much brighter appearance, while glaciated ice crystal clouds appeared as varying shades of pink). As much as 7 inches of snow remained on the ground that morning at Williston in northwestern North Dakota (station identifier KISN) as well as at a couple of stations in southwestern Manitoba. Also note that along the Missouri River there is a significant amount of ice remaining on much of the eastern half of Lake Sakakawea in the vicinity of Garrison, North Dakota (station identifier KN60).

MODIS false color Red/Green/Blue (RGB) images

CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS images and products available for National Weather Service offices to add to their local AWIPS workstations.

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MODIS 0.65 and 0.87 µm visible images (centered on Tuscaloosa, Alabama)

A comparison of 250-meter resolution Aqua MODIS 0.65 µm and 0.87 µm visible channel images centered on Tuscaloosa, Alabama on 28 April 2011 (above) showed signatures of a few of the larger and longer tornado damage paths from the historic tornado outbreak (SPC storm reports) that occurred on 27 April 2011. A collection of GOES, POES AVHRR, and MODIS images of the tornado outbreak are available on a separate CIMSS Satellite Blog post.

A comparison of before (17 April 2011) and after (28 April 2011) 250-meter resolution MODIS true color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) also showed a few of the tornado damage paths — though some of the damage paths were not as evident as they were on the single-channel visible images above. In addition, another long tornado track can be seen across western Georgia.

MODIS true color images before (17 April) and after (28 April) the tornado outbreak

Below is the same before/after MODIS true color image comparison, viewed using Google Earth.

Before (17 April) and after (28 April) MODIS true color images (viewed using Google Earth)

A comparison of AWIPS images of 1-km resolution MODIS 0.65 µm visible channel data and the corresponding 1-km resolution Normalized Difference Vegetation Index (NDVI) product (below) revealed that a few of the larger tornado damage paths were characterized by a slightly lower NDVI value (lighter green color), due to the downed trees and damaged vegetation.

MODIS 0.65 µm visible image + MODIS Normalized Difference Vegetation Index product

One of the larger tornado damage tracks across northwestern Alabama was also apparent on GOES-13 0.63 µm visible channel imagery (below). An animation helps to confirm that the feature is not a contrail or some other type of linear cloud feature (which would be moving in an animation, rather than stationary). While the north-south spatial resolution of the GOES imager visible detectors is 1.0 km at the satellite sub-point (over the Equator), with the larger geostationary satellite viewing angle the north-south spatial resolution over northern Alabama is about 1.38 km.

GOES-13 visible images (centered along Mississippi/Alabama border region)

It is interesting to note that the larger tornado damage path which can been seen across northwestern Alabama on the GOES-13 visible image is very difficult to identify on the corresponding GOES-12 0.65 µm visible image (below). This is due to a change is the spectral response function on the visible channel of the GOES-13 and later series of imagery instruments — for more details, see this CIMSS Satellite Blog post.

GOES-13 0.63 µm visible image (left) + GOES-12 0.65 µm visible image (right)

Update 29 April 2011: A Terra MODIS pass from late morning on April 29th shows the damage paths more clearly through central Alabama. As the churned-up vegetation within the damage path slowly browns, the contrast to undamaged vegetation outside the damage path should increase, allowing for a clearer picture of the damage path. The bowtie-corrected MODIS imagery for visible channel 1 (0.65 microns, below) and visible Channel 2 show three lines of damage through central Alabama. (Here is an animation of the two visible channels).

Since this day was less cloudy than the previous, here is a better before (17 April) versus after (29 April) comparison of 250-meter resolution MODIS true color images from the SSEC MODIS Today site (below, viewed using Google Earth).

MODIS true color images from before (17 April) and after (29 April)

Update 30 April 2011: A few of the tornado damage paths across northern Alabama were also evident on an AWIPS image of the 1-km resolution MODIS Land Surface Temperature (LST) product (below). The LST values within the damage paths were in the low to middle 80s F (darker red color enhancement), compared to surrounding LST values in the upper 70s F (orange color enhancement), indicating that the damage paths with destroyed vegetation and tornado debris were able to heat up a few degrees more than the adjacent undisturbed vegetation. The urban areas of the cities of Tuscaloosa (KTCL) and Birmingham (KBHM) also exhibited warmer LST values (darker red) than the surrounding less urbanized, more densely forested areas.

MODIS Land Surface Temperature product

CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS images and products available for National Weather Service offices to add to their local AWIPS workstations.

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