Dust Storm in the Plains Captured Well in MODIS Dust RGB Imagery…

On Thursday, October 18th, high winds affected drought-stricken areas of the central high plains as a tight pressure gradient developed between a broad low pressure system in the upper Midwest and a ridge of high pressure centered over the Inter-Mountain West.  Surface winds gusting around 50-70 mph were common across an area from the Dakotas through western and central portions of Nebraska and Kansas.   With much of this area experiencing exceptional (D4) drought conditions (Figure 1), a large plume of dust was generated mainly in western Nebraska, which then spread rapidly downstream.

Figure 1. U.S. Drought Monitor for the High Plains, October 16, 2012. Notice the broad expanse of exceptional (D4) drought conditions across Nebraska and western Kansas.

West to northwest winds around the base of the broad trough sent the dust plume racing across the mid-Mississippi Valley and into the Tennessee Valley regions overnight.  The dust could be seen in visible imagery yesterday afternoon (Figure 2).

Figure 2. GOES 1 km visible image valid 2031Z 18 October 2012. The plume of dust is indicated by the light gray colors stretching from SW Nebraska across Kansas into northern Olkahoma. An area of low clouds (bright white colors) can be seen to the northeast across the Midwest. Notice winds gusting around 40-50 knots in this region.

However, the dust showed up very well in MODIS Dust RGB imagery (Figures 3-6). Notice the spatial evolution of the dust plume, as it developed in western Nebraska, then migrated SE into Kansas and then eastward across the afore-mentioned regions.

Figure 3. MODIS 1 km resolution Dust RGB product valid 1831Z 18 October 2012 provided by NASA/SPoRT viewed in Google Earth via KML file. The yellow circle indicates the dust plume that originated in SW Nebraska. The dust shows up as the bright pink/red colors in the dust RGB imagery.  Unfortunately, the data availability was along the edge of the swath from the Terra satellite.

Figure 4. MODIS 1 km resolution Dust RGB product valid 2013Z 18 October 2012 provided by NASA/SPoRT viewed in Google Earth via KML file. The yellow circle indicates the dust plume that originated in SW Nebraska.  The dust plume is captured completely in this better pass of the Aqua satellite a little later.

Figure 5. SPoRT 1 km resolution Dust RGB product valid 0358Z 19 October 2012. The yellow circle indicates the dust plume that originated in SW Nebraska. In this nighttime image, the dust shows up as a brighter pink/puple color when compared to the softer pinks and light purples of the cooling surface. Notice the highest concentration of dust was across central portions of Oklahoma into western Arkansas.

Although much more diffuse and less discernible, the yellow circle shows the likely location of the best concentration of dust in figure 6 below. With radiational cooling conditions overnight, the colder 10.8µm channel retrievals cause less blue color in the background surface image. The highest concentration of dust continues to block the 10.8um radiation effectively, however differencing between the 12.0µm and 10.8µm channels decreases, also causing less red contribution.  The result is a more intense purplish coloration for the area of dust. Notice the dust had moved into western portions of the Tennessee Valley by the time of the image below. Observations from this time (not shown) indicated cloud celings around 3-6 kft AGL in the region of dust, where clouds clearly did not exist.

Figure 6.  SPoRT 1 km resolution Dust RGB product valid 0810Z 19 October 2012.

The leading edge of the apparent dust plume in the imagery above corresponds well with data from the Mobile Integrated Profiling System (MIPS) located at the University of Alabama-Huntsville.  As shown in figure 7 below, the ceilometer began to detect dust aloft at about 0700Z.  The dust becomes thicker aloft and appearently reaches the surface shortly after 0800Z.

Figure 7. Ceilometer imagery from the Mobile Integrated Profiling System (MIPS) located at the Univeristy of Alabama-Huntsville, beginning ~16Z 18 Oct continuing through ~16Z 19 Oct). Time elapses from left to right.

A picture atop the National Space Science and Technology Center bulding (Picture 1, below), which houses the National Weather Service office in Huntsville, AL and the NASA SPoRT center shows the dust in the early morning sky.

Image 1. Photograph taken atop the NSSTC building (looking east) at about 0730 CDT (1230Z).

3 thoughts on “Dust Storm in the Plains Captured Well in MODIS Dust RGB Imagery…

  1. Great post Huntsville! Bringing in the UAH profiler system really shows the unique capabilties we have here at the NSSTC.

    You note the difficulty detecting the dust in the early morning hours. You correctly point out that the cool ground is a contributing factor. In fact, the product is generated from two sets of split window channel differences. As nocturnal temperature inversions form, the split window differences loose their sensitivity to atmospheric features. The sensitivity returns during the day as can be seen in todays afternoon imagery (not shown here).

    Just imagine after the launch of GOES-R, the utility of this type of imagery every 5 minutes from the ABI. Revolutionary!

  2. Pingback: Dust plume to reach WNC mountains? | Ashvegas

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