The GOES-13 Sounder has been experiencing anomalies that manifest themselves as missing pixels since mid-Summer. The missing pixels apparently arise because of slight fluctuations in the speed of the sounder instrument filter wheel. The number of missing pixels per Sounder image peaked in late September, just after the Equinox, with up to 700 missing pixels (out of 63000) per Sounder image over CONUS. At present, missing pixels vary between 100 and 250, with a maximum typically around 2200 UTC and a minimum between 0600 and 1000 UTC. In the animation above, the missing pixels show as black; the GOES-15 Sounder data have no missing pixels.

Realtime GOES Sounder imagery is available at this link. The Sounder anomalies are present in all 19 of the GOES-13 spectral bands, as evident in the toggle below between an image in late September (when error counts were highest) and early November (when error counts were lower). GOES Engineers continue to monitor this situation and investigate possible solutions.

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Hat tip to NWS Buffalo NY forecasters Jon Hitchcock and David Zaff for letting us know about a number of aircraft dissipation trails (also known as “distrails” or “hole punch clouds”) over the Lake Ontario region on 04 November 2013. A series of McIDAS images of 1-km resolution GOES-13 Visible (0.63 µm) data (above) showed these features as they drifted eastward during the day.

A comparison of AWIPS II images of 375-meter resolution Suomi NPP VIIRS Visible (0.64 µm) visible and the corresponding False Color “Snow Cloud Discrimination” Red-Green-Blue (RGB) at 18:17 UTC (below) indicated that the cloud layer penetrated by aircraft was composed of supercooled water droplets (which appear as brighter shades of white on the RGB image) — but the particles in the aircraft exhaust acted as ice nuclei and caused the cloud to glaciate (ice crystal clouds appear as varying shades of red on the RGB image).

AWIPS images of the POES AVHRR CLAVR-x Cloud Type product confirmed that the cloud layer over the Lake Ontario region was a supercooled water droplet cloud (green color), with the Cloud Top Height product indicating tops in the 7-9 km range (below). However, higher-altitude cirrus clouds were beginning to overspread the region from the west (Cirrus=orange; Thick Ice=yellow; Overlap=violet).

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A rare “hybrid” solar eclipse occurred on 03 November 2013 (photos), which began over the western Atlantic Ocean as an annular eclipse and transitioned into a full total solar eclipse for observers along the narrow path of totality in the far eastern Atlantic and over parts of Africa (map of eclipse path). The Lunar Umbra (or solar eclipse shadow) could be seen tracking rapidly southeastward across the Atlantic Ocean on EUMETSAT Meteosat-10 0.635 µm visible channel images from 10:45-14:30 UTC (above; click image to play animation).

The dark solar eclipse shadow could also be seen near the edge of the Full Disk scan of the GOES-13 satellite at 11:45 UTC, just south and southwest of the Cape Verde Islands (below). Since the current generation of GOES only perform a full disk scan once every 3 hours,  the eclipse shadow could not be followed in time as it was using the 15-minute interval images from Meteosat-10.

With the next-generation GOES-R series, a full disk scan will occur once every 5 minutes. As a part of the GOES-14 Super Rapid Scan for GOES-R (SRSOR) testing, full disk scans were performed every 30 minutes on 14 September 2012.

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Sting jets are wind maxima near the end of bent-back fronts in cases of strong cyclones. As noted earlier on this blog, they can acquire a characteristic look in water vapor imagery, vaguely reminiscent of a scorpion’s stinger. In addition, strongly sinking air around the jet, usually associated with both a tropopause fold and a maximum in ozone, is manifest as a warm (dry) patch in the water vapor (WV) imagery. In the animation above, the sting jet is apparent moving across northern Denmark into southern Sweden between 1500 and 1800 UTC. This is in association with the ‘St. Jude’ storm that killed more than a dozen across northern Europe (Reuters news story).

The strong sinking near a sting jet can transport momentum down to the surface. You should therefore expect to see strong surface wind gusts near the water vapor satellite signature, and that was the case on October 28, as shown below.

Suomi/NPP viewed this storm early in the day on 28 October. The toggle between the VIIRS Day/Night Band and the 11.45 µm IR data, below, shows a developing baroclinic leaf over the British Isles.

A comparison of Aqua MODIS 0.65 µm visible, 11.0 µm IR, and 6.7 µm water vapor channel images visualized using the SSEC Web map Server (below; courtesy of Russ Dengel and Kathy Strabala, SSEC) showed the storm at 12:14 UTC on 28 October. The warm/dry signature of strongly-subsiding middle to lower tropospheric air was particularly evident on the water vapor image (yellow to orange color enhancement) as it was beginning to move eastward over Denmark.

For additional satellite images of this event, see the EUMETSAT Image Library and the Wide World of SPoRT.

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