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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MODIS volcanic ash mass loading, ash height, and ash effective radius products

According to the Alaska Volcano Observatory, the Mount Cleveland volcano erupted around 22:05 UTC on 19 June 2012 (volcanic activity notice). A comparison of AWIPS images of the MODIS volcanic ash mass loading, ash height, and ash effective radius products (above) showed the volcanic ash plume about 1 hour and 40 minutes later (23:44 UTC). The products indicated that the mass loading was as high as 5.1 tons per square km, the maximum ash height was 7.92 km, and the maximum ash effective radius was 11.95 µm.

A comparison of a 23:43 UTC POES AVHRR 0.86 µm visible image with the corresponding 12.0 µm IR image (below) showed no discernable signal of the volcanic ash plume.

POES AVHRR 0.86 µm visible channel image + 12.0 µm IR channel image

A 375-meter resolution Suomi NPP VIIRS 3.74 µm shortwave IR image (below) revealed a “hot spot” (yellow to red color enhancement) associated with the Mount Cleveland volcanic eruption. The maximum IR brightness temerature within the volcanic hot spot was 337.46 K or 64.31º C.

Suomi NPP VIIRS 3.74 µm shortwave IR image

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