The VIIRS instrument on NASA’s recently-launched NPP satellite began to acquire imagery on 21 November 2011 (NASA news release). True Color Red-Green-Blue (RGB) images from two of the early satellite passes are shown, which cover a swath from Brazil to eastern Canada from 16:10 to 16:35 UTC (above) and another swath covering much of eastern North America from 18:00 to 18:15 UTC (below).

A VIIRS RGB image covering parts of western Australia from 05:35 to 05:45 UTC on 22 November can be seen below.

Images created at the Space Science and Engineering Center (SSEC), University of Wisconsin-Madison by the NASA NPP Atmosphere PEATE Team.

Technical notes:
– Produced by Liam Gumley and Willem Marais (SSEC)
– SDR products ingested from the NPP SD3E by Bruce Flynn, Steve Dutcher, and Greg Quinn (SSEC)
– VIIRS M-bands SVM05, SVM04, SVM03 (red, green, blue)
– 1000 meter resolution, Cylindrical Equidistant projection
– Atmospheric correction algorithm by Jacques Descloitres (Formerly GSFC)
– Reprojection algorithm by Terry Haran (NSIDC)

Additional NPP VIIRS images can be found on the VIIRS Imagery and Visualization Team site at CIRA/RAMMB.

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1-km resolution GOES-13 0.63 µm visible channel images (above; click image to play animation) revealed a mesoscale vortex (or “mesolow”) propagating slowly westward across the western end of Lake Ontario on 21 November 2011. The GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5-10 minutes. With high pressure located to the north over western Quebec, the surface winds were generally light from the east across the region — and with a stable air mass in place, no precipitation was reported at any of the observing stations as the mesolow approached the coast and moved inland.

The structure of the mesoscale vortex could also be seen using 250-meter resolution Terra and Aqua MODIS true color images from the SSEC MODIS Today site (below).

In addition, the mesolow could also be seen on a true color image from one of the early overpasses of the VIIRS instrument on the NPP satellite (below).

Thanks to David Zaff and Robert Hamilton of the NWS Buffalo forecast office for bringing this feature to our attention!

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According to the National Hurricane Center, on 20 November 2011 Tropical Storm Kenneth became the latest-forming named tropical storm in the eastern North Pacific basin since Hurricane Winnie formed on 04 December 1983. GOES-11 0.65 µm visible channel images from the CIMSS Tropical Cyclones site (above) showed a well-defined circulation, with a ship report of tropical storm force winds north of the storm center.

The corresponding GOES-11 10.7 µm IR images (below) showed a trend of increasing convection withing the northern semicircle of the storm.

AWIPS images of the MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) indicated that TPW values associated with Tropical Storm Kenneth were in the 50-60 mm range (darker orange colors), as rich moisture was sill in place along the Inter-Tropical Convergence Zone (ITCZ) / Monsoon Trough.

======== 21 November Update ========

Kenneth was upgraded to a Hurricane on 21 November. GOES-15 0.63 µm visible channel images (above; click image to play animation) showed a ragged eye forming as curved convective bands wrapped around the center of the tropical cyclone. Kenneth was able to intensify in part because it was in an environment that possessed uncharacteristically low values of deep layer wind shear (below).

======== 22 November Update ========

Hurricane Kenneth strengthened to a Category 4 storm on 22 November, becoming the most intense major hurricane to form so late in the season in the satellite era. GOES-15 0.63 µm visible channel images (above; click image to play animation) showed the well-defined eye of Kenneth.

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A comparison of an AWIPS image of 1-km resolution MODIS 0.65 µm visible channel data with the corresponding MODIS false color Red/Green/Blue (RGB) image created using the 2.1 µm “snow/ice channel” (above) showed that snow cover was beginning to increase in areal extent across parts of the north-central US on 20 November 2011. This example also demonstrates the utility of RGB imagery for helping to discriminate between snow cover (which shows up as shades of red on the RGB image) and supercooled water droplet clouds (which show up as varying shades of white). Snow depths at the time included 11 inches at Mount Rushmore, South Dakota, 10 inches at Rice, Minnesota and 5 inches at Minot, North Dakota.

MODIS false color RGB images created using data from consecutive overpasses of the Terra (17:22 UTC) and Aqua (19:03 UTC) satellites (below) also show the movement of the low cloud features during that period.

As pointed out in the NWS Minneapolis Area Forecast Discussion, the swath of fresh snow cover would have an impact on daily high and low temperatures at locations where the snow was deepest. An AWIPS image of the 1-km resolution MODIS Land Surface Temperature (LST) product (below) revealed that LST values were in the 0º F to +10º F range (cyan to blue color enhancement) over the areas with snow cover, in contrast to LST values in the 30s F (green color enhancement) over adjacent areas with bare ground.

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. Currently there are 49 NWS offices receiving MODIS imagery and products from CIMSS.

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