MODIS true-color image, Sea Surface Temperature product, and 0.65 µm visible channel image

AWIPS comparisons of a 250-meter resolution MODIS true-color Red/Green/Blue (RGB) image at 16:46 UTC on 21 June 2012 with the corresponding 1-km resolution MODIS Sea Surface Temperature product and 0.65 µm visible channel image (above) revealed the vivid signature of iron and/or copper rich runoff sediment in the near-shore waters of western Lake Superior following the historic heavy rainfall event of 19 June – 20 June 2012 (for more details on this event, see the Duluth National Weather Service).

A “before” (21 May 2012) and “after” (21 June 2012) true color image from the SSEC MODIS Today site (below) showed the dramatic change in appearance of the western Lake Superior near-shore waters.

MODIS true-color images (21 May 2012 and 21 June 2012)

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7-day total precipitation, percent of normal, and departure from normal

Maps of the total 7-day precipitation, percent of normal precipitation, and precipitation departure from normal (above) highlighted the extreme nature of the event in the Duluth region, but also showed the large amount of variability in precipitation across other portions of the Upper Midwest states during this period.

In particular, note the large southwest-to-northeast oriented swath across northeastern Nebraska, northwestern Iowa, southeastern South Dakota, and southwestern Minnesota (below): in this highly agricultural area, the stress on the crops within this rain-free swath was apparent on MODIS 0.65 µm visible imagery (lighter gray where the vegetation was less healthy), the MODIS Land Surface Temperature (LST) product (LST values in the upper 80s to mid 90s F, surrounded by LST values in the 70s F), and the Normalized Difference Vegetation Index (NDVI values as low as 0.43 in southwestern Minnesota, surrounded by NDVI values of 0.7 to 0.8 to the north and to the south where ample rainfall had been occurring).

MODIS 0.65 µm visible image, Land Surface Temperature product, and Normalized Difference Vegetation Index product

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GOES-15 0.63 µm visible channel images (click image to play animation)

GOES-15 0.63 µm visible channel images (above; click image to play animation) revealed the interesting convergence of an undular bore (which was propagating northwestward) and a von Karman vortex street (which was moving southeastward, downwind of Guadeloupe Island) on 20 June 2012. Both of these features were likely traveling within the stable marine boundary layer.

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GOES Sounder Imagery during Filter Wheel Anomaly

On June 20, 2012, the GOES-13 Sounder Filter Wheel mechanism suffered an anomaly. The filter wheel moves the spectral filters into the optical path of sensed radiation. As a result of the anomaly, data quality was degraded starting at about 1248 UTC. Instrument recovery activities occurred at 1756 UTC on 20 June, and qualitatively the data returned to normal. Imager data were not affected.

GOES Sounder Imagery during Filter Wheel Anomaly

When GOES Sounder data are degraded, GOES Sounder Derived Product Imagery is also degraded. For example, the Precipitable Water image from 1746 UTC on June 20 is shown above. GOES-15 Sounder data returns over the western United States do not show the data dropouts characterized by the Filter Wheel Anomalies in GOES-13 over the eastern United States.

Filter Wheel anomalies have occurred in the past on GOES-12. GOES-10 Filter Wheel anomalies caused a data interruption on GOES-10 from Oct 14th to Nov 6th, 2008. GOES-8 also suffered from rare filter wheel anomaly issues (Link).

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WMS Image of Tropical Storm Chris and SSTs

The image above from the SSEC Web Map Service (WMS) shows visible imagery of Tropical Storm Chris over the central Atlantic on June 20th, just south of the north wall of the Gulf Stream. Sea-surface temperatures are indicated by the color shading. The projected path of the storm, and the cone of uncertainty (retrieved from the NOAA nowcoast wms), are also indicated. The path takes the storm over the cold waters of the North Atlantic, so strengthening to hurricane status is unlikely, especially after today. (Added: Click here for QuickTime animation of WMS images)

For more information on Chris, please see the National Hurricane Center website, or the CIMSS Tropical Cyclones website.

===== 21 June Update =====

GOES-13 10.7 µm IR channel images (click image to play animation)

Chris did manage to reach hurricane intensity for several hours on 21 June 2012 (NHC advisory), becoming the first hurricane of the 2012 North Atlantic season.  GOES-13 10.7 µm IR channel images (above; click image to play animation) showed a well-defined eye during this period.

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