Suomi NPP VIIRS 0.64 µm visible channel, 3.74 µm shortwave IR channel, and 11.45 µm IR channel images

A comparison of AWIPS images of Suomi NPP VIIRS 0.64 µm visible channel, 3.74 µm shortwave IR channel, and 11.45 µm IR channel data (above) showed a broad “vog” plume streaming westward off the Big Island of Hawaii on 10 January 2013. The primary source of this vog plume was likely the active Kilauea volcano — and the 3.64 µm shortwave IR image revealed a small “hot spot” at the summit of the volcano, which exhibited a brightness temperature value of 49.5º C (orange color enhancement).

The VIIRS 0.64 µm visible channel image with an overlay of 1-hour interval MADIS atmospheric motion vectors (or “satellite cloud-tracked winds”) showed the typical easterly trade wind flow regime that usually transports the vog plume westward away from the Hawaiian Islands (below). However, synoptic-scale disturbances that disrupt this trade wind flow can cause the vog plume to move over inhabitied portions of the islands, causing air quality problems.

Suomi NPP VIIRS 0.64 µm visible channel image + MADIS 1-hour interval atmospheric motion vectors

Other examples of Hawaiian vog plumes can be found here on the CIMSS Satellite Blog.

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Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR images

A comparison of AWIPS images of Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) and 11.45 µm IR channel data at 08:36 UTC (or 2:36 AM local time) on 09 January 2013 (above) showed a few items of interest on the DNB “visible image at night”:

1. Even though there was deep convection with very cold (-70 to -75º C, black to light gray enhancement) cloud tops covering much of the eastern half of Texas, the diffuse glow of city lights could still be seen through the clouds
2. Two elongated bright streaks off the southern tip of Texas: signatures of cloud-top illumination by lightning
3. The relatively sparsely-populated area of far southeastern New Mexico and the adjacent New Mexico/Texas border region exhibited a pronounced signature of bright illumination
4. In central New Mexico, where it was relatively cloud-free, portions of the Interstate highways — especially Interstate 40 that ran west-to-east between Albuquerque KABQ and Amarillo KAMA — appeared to be nearly continuously illuminated (presumably by a combination of small towns, truck stops, etc. and the headlights of vehicle traffic along the route)

POES AVHRR Cloud Top Height product

Regarding point number 1 with the city light signatures, let’s attempt to explore how thick the clouds were over eastern Texas. An AWIPS image of the POES AVHRR Cloud Top Height product about an hour later at 09:50 UTC (above) indicated that the vast majority of the cloud tops were in the 11-13 km or 36,000-43,000 feet range. The VIIRS IR cloud top brightness temperatures as cold as -70 to -75 C agreed well with the temperature of the tropopause on the 12 UTC Fort Worth, Texas rawinsonde report (the tropopause height on that sounding was around 43,000 feet).

Surface station cloud ceiling and visibility data plotted on the VIIRS IR image (below) showed that overcast cloud bases nearest to the area of the coldest IR cloud top temperatures were 3500 feet above ground level at Temple KTPL and 5500 feet above ground level at Waco KACT. Outside of the main convective updraft cores the cloudiness was likely distributed within a number of discrete layers, but the fact that such a bright (albeit diffuse) signature of city lights could be seen through 30,000-40,000 feet of cloud layers is rather remarkable.

Suomi NPP VIIRS 11.45 µm IR image with surface reports of cloud ceiling and visibility

Regarding point number 3 with the bright lights seen across far southeastern New Mexico and the adjacent New Mexico/Texas border region, that is due to widespread drilling activity in the Avalon / Bone Spring oil shale region. While some natural gas flares might be present, the vast majority of the bright signatures are likely due to illuminated “man camps” that house the drilling support crews. Similar night-time illumination signatures are seen in the Eagle Ford and Bakken oil shale drilling regions.

===== 10 January Update =====

Suomi NPP VIIRS 0.7 µm Day/Night Band image

The deep convection persisted off the coast of Texas into 10 January — a Suomi NPP VIIRS 0.7 µm Day/Night Band image at 08:17 UTC or 2:17 AM local time (above) displayed a large number of elongated bright streaks as the sensor detected lightning-illuminated clouds.

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MODIS 0.65 µm visible channel and 6.7 µm water vapor channel images

AWIPS images of 1-km resolution 6.7 µm water vapor channel data (above) revealed interesting wave patterns over parts of southern California, Baja California, and the adjacent offshore waters of the Pacific Ocean on 07 January 2013. A comparison with the corresponding 0.65 µm MODIS visible image showed that there were no clouds associated with any of these water vapor wave features. The mountain waves over southern California and northern Baja California were caused by strong winds on the western periphery of an upper-level low pressure system — and there were  isolated pilot reports of moderate turbulence  over southern California at the 30,000-34.000 foot altitude range.

Also of interest is the “bow shock wave” feature seen on the water vapor image, which fans out downwind (southward) of Guadalupe Island (station identifier 76151). These waves were caused by the interaction of lower-tropospheric winds from the north interacting with the high terrain of the volcanic island (whose highest point is Mount Augusta at 4257 feet or 1298 meters). Lower-tropospheric satellite winds off the west coast of Baja California were as strong as 37 knots at the 812 hPa pressure level.

McIDAS images of 4-km resolution GOES-15 6.5 µm water vapor channel data (below; click image to play animation) suggested that there was strong middle-tropospheric subsidence over the region surrounding Guadalupe Island  — as seen by the warming/drying trend (the transition to brighter yellow colors) — which allowed the weighting function of the water vapor channel to peak at lower altitudes in order to detect the  lower-level signature of the bow shock wave.

GOES-15 6.5 µm water vapor channel images (click image to play animation)

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Suomi NPP VIIRS 11.45 µm IR image (with METAR surface reports)

The coldest temperature in the United States (including Alaska) was -33 F (-36 C) at Alamosa, Colorado on 03 January 2013. AWIPS images of 375-meter resolution (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 11.45 µm IR data with METAR surface reports (above) showed a few areas in parts of the higher elevations of central Colorado which exhibited IR brightness temperatures as cold as -44 C or -47 F (white color enhancement). In the lower left portion of the image, the warmer signature (red color enhancement) of the Colorado River basin could be seen running southwestward across Utah and into the Grand Canyon region of Arizona.

Alamosa (station identifier KALS) is located in south-central Colorado, and is situated in the eastern portion of the broad high-altitude basin of the San Luis Valley. The Suomi NPP VIIRS 0.7 µm Day/Night Band image (below) showed the brighter white signature of the moonlit snow-covered San Luis Valley at night (08:49 UTC = 1:49 AM local time). Much of the western (high-elevation) half of Colorado had substantial snow cover, and there were a few other sites that recorded minimum temperatures of -30 F or colder.

Suomi NPP VIIRS 0.7 µm Day/Night Band image (with METAR surface reports)

A comparison of the Suomi NPP VIIRS IR brightness temperature difference “fog/stratus product” and the corresponding GOES-13 Cloud Thickness and IFR Probability products (below) indicated that most of the higher elevations of central Colorado were generally cloud-free, which allowed for strong radiational cooling to reach such cold surface temperatures.

Suomi NPP VIIRS “fog/stratus product” + GOES-13 Cloud Thickness and IFR Probability products

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