GOES-11 6.7 µm water vapor images

There were three items of interest to discuss that exhibited interesting satellite signatures on 13 July 2010. The first feature was a middle-tropospheric vortex that was spinning off the coast of California, as seen on AWIPS images of 8-km resolution GOES-11 6.7 µm water vapor channel data (above). However, note the striking improvement in the details of this vortex that could be seen using the 1-km resolution MODIS 6.7 µm water vapor image (below).

GOES-11 6.7 µm and MODIS 6.7 µm water vapor images

The second feature of interest was a very large smoke plume that was spreading northeastward from a wildfire that was burning in northeastern Idaho. The so-called “Jefferson fire” started on the property of the Idaho National Laboratory (INL) and quickly grew in size to about 109,000 acres, making it the largest fire in INL history (it was also the largest fire burning at the time in the entire US). Note the rapid growth in size of the smoke plume on the McIDAS image comparison of GOES-11 (GOES-West) 0.65 µm visible channel, GOES-15 0.63 µm visible channel, and GOES-13 (GOES-East) 0.63 µm visible channel data (below) — each of the image sets are displayed in the native projection of the respective GOES satellite. GOES-13 was in Rapid Scan Operations (RSO) mode, so images were available more frequently (as often as every 5-10 minutes) than from either GOES-11 or GOES-15. The smoke plume was seen to quickly spread across western Wyoming as night-time approached and visible imagery became unavailable.

GOES-11, GOES-15, and GOES-13 visible images

A few hours after the final GOES visible images, an AWIPS comparison of the 4-km resolution GOES-11 3.9 µm shortwave IR image and the corresponding 1-km resolution MODIS 3.7 µm shortwave IR image (below) demonstrated that more accurate information about the location of the active fire hot spots could be determined using the higher spatial resolution MODIS data. The MODIS shortwave IR image displayed a number of very hot pixels (yellow color enhancement) along the southern periphery of the burn area, which were not evident on the GOES-11 shortwave IR image.

GOES-11 3.9 µm and MODIS 3.7 µm shortwave IR images

On the following day (14 July), 250-meter resolution Red/Green/Blue (RGB) true color (using bands 1/4/3) and false color (using bands 7/2/1) images from the SSEC MODIS Today site (below) showed a close-up view of the burn scar feature (located in the right center portion of the images). A small  smoke plume was still evident on the true color image, streaming northeastward from the northern periphery of the burn scar area.

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

The final feature of interest was a severe thunderstorm that had developed over southeastern North Dakota. Since GOES-13 had been placed into RSO mode, a sequence of 4 images (between 19:25 and 19:45 UTC) is shown (below) around the time that the storm produced a wind gust of 61 knots (70 mph).

GOES-13 10.7 µm IR images

During that same time period, a sequence of 1-km resolution POES AVHRR 10.8 µm IR and MODIS 11.0 µm IR images (below) showed much greater detail in the cloud top temperature structure of the severe thunderstorm. Due to the finer spatial resolution, the coldest storm top IR brightness temperature value seen on the 1-km imagery was -73º C (compared to only -60º C on the 4-km GOES imagery).

POES AVHRR 10.8 µm and MODIS 11.0 µm IR images

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

Strong northwesterly winds behind a cold front gusted as high as 55 mph at Magee Peak in Washington State on 12 July 2010, causing some traffic accidents and road closures due to low visibility from blowing dust — and the blowing dust ended up restricting surface visibility to 2 miles as far to the east as Spokane (station identifier KGEG). A write-up of the event by the NWS forecast office at Spokane showed some web camera views of the dust. An AWIPS image of the 1-km resolution 0.65 µm visible channel data (above) did reveal two distinct aerosol plumes: one originating to the northwest of Wenatchee (station identifier KEAT), and another originating to the north and northeast of Moses Lake (station identifier KMWH). These aerosol plumes appeared to be originating from areas with a low Normalized Difference Vegetation Index (NDVI) value, suggesting dry land void of crops, trees, or other vegetation.

A comparison of MODIS 0.65 µm visible and MODIS 6.7 µm water vapor channel images (below) indicated that there was a mountain wave (to the lee of the Cascade Range) present over the region with the plumes, which may have acted as a mechanism to help transfer some of the strong momentum aloft downward toward the surface.

MODIS 0.65 µm visible image + MODIS 6.7 µm water vapor channel image

Note how this mountain wave signature as seen with MODIS was not evident at all on the corresponding 8-km resolution GOES-11 6.7 µm water vapor channel image (below).

1-km resolution MODIS + 8-km resolution GOES-11 6.7 µm water vapor images

A closer look using 250-meter resolution MODIS true color and false color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) was helpful in determining that the westernmost plume was actually smoke from a wildfire (the fire hot spots and burn scar showed up as red to pink on the false color image, and the smoke plume itself was brighter on the true color image). In contrast, the blowing dust plume farther to the east had more of a light brown to tan appearance on the true color image.

250-meter resolution MODIS true color and false color RGB images

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MODIS 3.7 µm shortwave IR image

The presence of an actively-burning fire was confirmed by a large cluster of hot pixels (dark black color enhancement) to the northwest of Wenatchee (station identifier KEAT) on MODIS 3.7 µm shortwave IR imagery (above). Farther to the south and southeast, the larger dark black area seen on the shortwave IR image corresponded to the sparsely-vegetated region around Hanford (station identifier KHMS), which was exhibiting MODIS Land Surface Temperature values in the 120-130º F range (below).

MODIS Land Surface Temperature product

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GOES-13 Sounder and Imager water vapor channels (00 UTC, 12 July)

An AWIPS 4-panel display of the three GOES-13 Sounder water vapor channel images along with the single GOES-13 Imager water vapor channel image (above) revealed that a pocket of warm brightness temperatures (denoting dryer air aloft) was in place over much of eastern Virginia and North Carolina around 00 UTC on 12 July 2010.

The corresponding plots of the GOES-13 Sounder (red, green, and blue plots) and GOES-13 Imager (black plot) water vapor channel weighting functions (below, calculated using 00 UTC rawinsonde data from Greensboro, North Carolina) showed a relatively uncommon “bi-modal” structure — this indicated that there were significant contributions from two distinct layers, such that the actual altitude of the features being displayed on the water vapor imagery over that region at that time would be difficult to ascertain.

Greensboro NC GOES-13 Sounder and Imager water vapor weighting function plots

However, 12 hours later, the same AWIPS 4-panel display of water vapor imagery around 12 UTC (below) showed that significant amounts of moisture and cloudiness had moved into the region that was relatively dry at 00 UTC.

GOES-13 Sounder and Imager water vapor channels (12 UTC, 12 July)

With the increased middle and upper tropospheric moisture, note that the 12 UTC  water vapor weighting function plots (below, calculated using 12 UTC rawinsonde data from Greensboro NC) all peaked at significantly higher altitudes — and by the shape of the weighting function plots, it was easier to tell the layer of the troposphere that was being sampled by each of the individual water vapor channels.

Greensboro NC GOES-13 Sounder and Imager water vapor weighting function plots

AWIPS images of the Blended Total Precipitable Water product (below) confirmed that there was a significant increase in total column moisture content over the Greensboro NC region during that 12-hour period. TPW values rose from about 21 mm to around 40 mm over Greensboro during that time.

Blended Total Precipitable Water product

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GOES-11 0.65 µm visible channel images

GOES-11 0.65 µm visible channel imagery (above) indicated that you would have been hard pressed to find a location along the entire West Coast of the US (from California to Washington State) that did not have fog or stratus clouds overhead during the morning hours on 09 July 2010!

During the preceding night-time hours (before visible imagery was available), a comparison of AWIPS images of the 1-km resolution MODIS fog/stratus product and the 4-km resolution GOES-11 fog/stratus product centered over central California (below) demonstrated the value of higher spatial resolution in determining just how far inland some of the fog and stratus features were located at around 06:30 UTC (11:30 pm local time).

MODIS and GOES-11 fog/stratus product images

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