RGB Examples from Early Morning Sep 20th…

With the RGB Imagery for Aviation and Cloudy Analysis evaluation underway, we’re already getting some good feedback from our end-users.  From WFO Morristown – “I looked at the Nighttime Microphysics product in hindsight to see how fog around TRI was depicted this morning.  The (RGB) product did an outstanding job of clearly showing areas of fog vs. clouds, even though there were some thin midlevel clouds over the fog areas.”  Below is a loop of the available MODIS (Aqua and Terra) and Suomi NPP VIIRS images from the southern Appalachain region early from late last evening through early this morning (click the image to see the loop).

Image 1.  Loop of Nighttime Microphysics RGB images: Terra MODIS (0359 UTC, Sep 20), Suomi NPP VIIRS (0736 UTC, Sep 20) and Aqua MODIS (0810 UTC, Sep 20).

Image 1. Loop of Nighttime Microphysics RGB images: Terra MODIS (0359 UTC, Sep 20), Suomi NPP VIIRS (0736 UTC, Sep 20) and Aqua MODIS (0810 UTC, Sep 20).

The image shows the early production of fog (ligher, aqua colors) in the Cumberland and Allegheny Plateau region of eastern Kentucky and SW Virginia by the time of the first MODIS pass at 0359 UTC.  Notice how the fog spreads to include other valley locations in East Tennessee by the time of the last images at 0736 UTC and 0810 UTC.

Meanwhile, the fog is clearly not as apparent using the standard 11-3.9 µm imagery (and standard color curve) even with the 1km Aqua MODIS image inserted (image 2, ~0810 – 0815 UTC).

Image 2.  Aqua MODIS and GOES-East hybrid 11-3.9 µm image valid ~0810-0815 UTC, Sep 20 2013

Image 2. Aqua MODIS and GOES-East hybrid 11-3.9 µm image valid ~0810-0815 UTC, Sep 20 2013

…and is even less noticable in the 4km GOES-East image alone a little later at 0832 UTC (image 3).

GOES-East 11-3.9 µm image valid 0832 UTC, Sep 20 2013

Image 3.  GOES-East 11-3.9 µm image valid 0832 UTC, Sep 20 2013

Fog in the narrow valleys in the region shows up quite well in the VIIRS Day/Night Band Radiance RGB, developed by SPoRT (image 4).  The forecaster noted that, “the DNB Radiance RGB showed fog clearly as well, but maybe not quite as well as the Nighttime Microphysics product.”  I would agree, however I was encouraged by the detail and the relative ease with which fog was discernible in the image.

Image 4.  Soumi NPP VIIRS Day/Night band Radiance RGB valid 0736 UTC, Sep 20 2013

Image 4. Soumi NPP VIIRS Day/Night band Radiance RGB valid 0736 UTC, Sep 20 2013

The typical issues with the timeliness of the polar-orbiting imagery, for opertional considerations, appears to be the largest concern for forecasters at this point in the survey process.  Of course, this won’t be an issue in the GOES-R era, and acquanting forecaters with these types of imagery before the next generation of GOES satellites is launched is an important step in the learning process.

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