Dust Storm Shown by VIIRS and MODIS in Southwest 2014

VIIRS True Color RGB imagery produced by NASA/SPoRT.  Southwest region domain at 1836UTC, 11 March 2014.

VIIRS True Color RGB imagery produced by NASA/SPoRT. Southwest region domain at 1836UTC, 11 March 2014.

In the southwest CONUS region, severe to extreme drought conditions exist in many areas.  In particular southwest Colorado, northeast New Mexico and the Texas and Oklahoma panhandle areas are very dry according to the U.S. Drought Monitor.  A building high pressure area developed a strong pressure gradient across these areas during the afternoon of 11 March 2014, resulting in 20-30 kt sustained northerly winds with gusts over 40 kt. Combined with the dry conditions, WFOs in the southwest have been anticipating blow dust events to be large and more frequent with strong Spring cyclones. VIIRS True Color RGB imagery (above) shows the blowing dust in Colorado and Texas, but the clouds in Colorado and Kansas have a similar color and the dry ground characteristics in Texas also look similar in color to the dust.  To provide a more efficient analysis of the blowing dust, VIIRS and MODIS can be used to create an RGB imagery product that shows blowing dust in shades of magenta to differentiate it from clouds and ground features.  This is done using the EUMETSAT recipe for the “Dust RGB” per their “Best Practices” after years of experience with the MeteoSat Second Generation SEVIRI instrument.  This geostationary instrument has similar capabilities to that of the future GOES-R ABI instrument.  Hence VIIRS and MODIS provide operational utility now and demonstrate future capabilities that all U.S. forecasters can use to be ready for the next generation of satellite products.  The VIIRS and MODIS passes show three times from this afternoon to aid forecasters with tracking the dust event.

20140311_1836_sport_viirs_swregion_dust_annotated

MODIS Dust RGB Imagery for 1941UTC 11 March 2014

MODIS Dust RGB Imagery for 1941UTC 11 March 2014

VIIRS Dust RGB Imagery for 2019UTC 11 March 2014

VIIRS Dust RGB Imagery for 2019UTC 11 March 2014

3 thoughts on “Dust Storm Shown by VIIRS and MODIS in Southwest 2014

  1. Greetings. This is my first post so forgive my ignorance :). The dust certainly stands out. We’ve found this imagery to be highly useful here at WFO Tucson.

    In this case, what are your thoughts on the darker purple more linear feature ahead of the dust. It looks like the front to me. From surface observations, the northerly wind shift was well south of the feature at the time of these images. However, the tight moisture and temperature gradients are much closer to the purple feature.

    Bottom line – would this be a good product to use when trying to identify baroblinic zones? Obviously a dry frontal passage would be helpful :).

    Thank you,

    JJ

  2. John,

    Very good question. If you look at the images from this dust event that I posted on the CIMSS Satellite Blog

    http://cimss.ssec.wisc.edu/goes/blog/archives/15100

    you will see that while the leading edge of the surface cold front was indeed well out ahead of (to the south of) the dense plumes of blowing dust, there were some narrow filaments of high cloud that appeared as the darker purple, more linear features that you are referring to on the SPoRT RGB images.

    -Scott

  3. John,

    The Dust RGB Quick Guide by NASA/SPoRT can be found at:
    http://weather.msfc.nasa.gov/sport/training/rgb_dust/RGB%20Dust%20Reference%20Guide.pdf

    The Quick Guide has a table at the top that describes the channels used and relates them to physical properties. With the RGB imagery, the darker the color the less contribution being made by individual R-G-B components. The dark purple features you mentioned are likely high clouds. There’s probably little red, indicating relatively thin clouds, and the small amount of blue suggests fairly cold clouds.

    Can the Dust RGB identify temperature gradients well? I have not see large value in this area. However, the Dust RGB can identify density differences well and hence, it can be used to analyze a dryline location pretty well. The Quick Guide has an example where this is pretty clear. In general, the moist air will have a greater blue tone vs the dry air areas that have more light purple tones.

    Kevin Fuell

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