October 19, 2012
Dust from Nebraska is predicted to head eastward to mid-Atlantic
In yesterday's post, Daniel pointed out that there was an area of dust coming out of Nebraska. In a comment today, Mark Ruminski of NOAA noted:
You may be interested to see a link that has some video and other info on this event:Accuweather link. Winds were quite stout with lots of reports of sustained winds of 40 kt and gusts over 50 kt in the area.
By the way, not surprisingly, there were also some fires that were caused by the strong winds in the area. So there was also some smoke mixed in with all the dust. Looking at today's GOES visible imagery, the NWS dust forecast still looks to be in fairly good shape as there is a broad area over the Tennessee Valley back into northeast Texas.
The forecast indicates the dust should be moving over the DC metro area and UMBC this evening and overnight.
The dust forecast Mark mention is shown in the panel to the left below. The band of dust in Terra MODIS this afternoon is quite visible. You may recall that MODIS Terra has degradation in the eastern part of the imager swath and that is why there is such a stark demarkation between the eastern edge of the western swath versus the western edge of the eastern swath. But the time of day is important and the dust shows up well at 10:30 in the morning. It is also visible in the Aqua MODIS image but not as clearly. The overlay of the AQI reading in the south show that the dust is clearly elevated and not affecting the surface air quality which remains good.
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The AOD image from IDEA shows the elevated AOD from the dust and shows the system which generated the high winds. The right image shows the NRL dust forecast for 12Z today.
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A final piece of evidence is a limited amount of AERONET data from Huntsville today. While the data is provisional level 1 data, there were readings of AOD=3 near noon and AOD =2 at 18Z. All channels on the sunphotometer read the same which indicates either a cloud (since it is white) or dust (since the Angstrom coefficient will be near zero).
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We have been asked questions about what happened to the GASP EAST product. GOES-13 suffered a malfunction and for the past few weeks GOES-15 has filled in by providing imagery. GOES-15 is not on station at 75°W so the viewing angles are not the same as for GOES-13. It is impossible to run the GASP algorithm on a satellite that is not at 75°W without changing the lookup tables. Since it was expected that GOES-13 would return to service (and it did that today), the changes were too much work for an operational environment. GOES-13 will start generating the GASP product again in 28 days after the algorithm has time to gather dark pixel data on clear scenes. NOAA apologizes for the discontinuity in service.