Another Example – Using VIIRS Day-Night Band RGBs for Better Fog Detection…

I wanted to follow up with this sooner, but I’ve been rather busy preparing for the NWA conference.  Yep, I tend to be one of those “last-minute” people.  Anyway, just last week I posted an example showcasing the advantage of the VIIRS Day-Night Band Radiance RGB in detecting fog through cirrus clouds.  The next day, SPoRT collaborator Doug Schneider (Morristown WFO), followed up with another great example that I wanted to share.  I’m just going to take an excerpt from an email he sent to the Morristown staff…

“I know I’ve been sending out quite a few emails lately about NASA SPoRT products, so please bear with me, but I thought this was a great example of how they can add value.

I’ve mentioned the MODIS/VIIRS Fog product before, but sometimes there are better products available for identifying fog, especially when thin cirrus are present. In the MODISVIIRS Fog product image that is attached, you can see that it is difficult to see the extent of fog. There’s clearly some in the Sequatchie Valley, but there is also some in the NE TN/SW VA area that can’t be easily seen.

The attached MODIS/VIIRS Nighttime Microphysics product also shows fog in the southern areas where it is clear (fog is light blue colors), but cirrus obscures NE sections.

The VIIRS Day/Night Band Radiance RGB product does the best job showing the extent of fog. Fog is clearly identified in the valleys of SW VA and NE TN, despite the presence of cirrus. The extent of fog is also more easily seen in the central and southern valley areas.

The attached menu image shows where you can find the Day/Night Band Radiance RGB product under the Satellite -> NASA SPoRT -> Polar Imager -> MODIS/VIIRS -> SR East menus.

Remember that these products are from a polar-orbiting satellite, and may only be available once a night, usually between 07z and 10z.”

I’ve included the images he referenced below, and circled the specific area of fog in NE Tennessee / SW Virginia that he was mentioning.

Suomi-NPP VIIRS Day-Night Band Radiance RGB, 0724 UTC 10 Oct 2014.  Circled area shows valley fog not detectable in subsequent GOES or VIIRS NT Microphysics images.

Suomi-NPP VIIRS Day-Night Band Radiance RGB, 0724 UTC 10 Oct 2014. Circled area shows valley fog not detectable in subsequent GOES or VIIRS NT Microphysics images.

Suomi-NPP VIIRS 11-3.9 um image, 0724 UTC 10 Oct 2014.  Notice that high cirrus clouds (blue colors) obscure the fog below.

Suomi-NPP VIIRS 11-3.9 um image, 0724 UTC 10 Oct 2014. Notice that high cirrus clouds (blue colors) obscure the fog below.

Suomi-NPP VIIRS Nighttime Microphysics RGB, 0724 UTC 10 Oct 2014.  Fog can be seen in other areas to the south/southwest, but not beneath the cold, cirrus clouds (under the yellow circle) since this RGB recipe contains multi-spectral IR components.

Suomi-NPP VIIRS Nighttime Microphysics RGB, 0724 UTC 10 Oct 2014. Fog can be seen in other areas to the south/southwest, but not beneath the cold, cirrus clouds (under the yellow circle) since this RGB recipe contains multi-spectral IR components.

This is exactly the kind of inter-office sharing SPoRT is looking for from our close partners.  We greatly thank Doug and the Morristown office for their collaborative efforts!

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