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

McIDAS images of 1-km resolution GOES-15 0.63 µm visible channel data (above) showed a large area of low pressure in the eastern Gulf of Alaska which was helping to draw a large amount of wildfire smoke southward on 19 July 2012. The hazy smoke aloft originated from wildfires in Alaska and in northeastern Asia.

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

Meanwhile, farther to the south, 1-km resolution GOES-15 visible channel images (above; click image to play animation) revealed that the circulation of the remnants of Hurricane Fabio was drawing marine boundary layer “ship track” clouds into its circulation — while some ships actually appeared to be headed right for the center of the dissipating tropical cyclone.

The ship tracks were also evident on 4-km resolution GOES-15 3.9 µm shortwave IR images (below; click image to play animation). The ship tracks appeared darker (warmer) on the shortwave IR imagery, due to the fact that the smaller cloud droplets of the ship track clouds reflected a higher amount of incoming solar radiation back toward the satellite sensors.

GOES-15 3.9 µm shortwave IR channel images (click image to play animation)

250-meter resolution Terra and Aqua MODIS true-color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) showed greater details of the ship tracks as they were drawn into the circulation center of the dying storm (along with the other ship tracks approaching the storm from the south).

Terra MODIS true-color Red/Green/Blue (RGB) image

Aqua MODIS true-color Red/Green/Blue (RGB) image

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VIIRS Day/Night Band from Suomi/NPP satellite

The New Moon on 18 July means that no visible light reflected from the Moon can illuminate clouds, and the day/night band on the Suomi-NPP satellite can therefore view any clouds only with difficulty. However, it still views city lights, and illuminated roads, or gas field flares, among other things. The region above shows data contaminated by stray light. The Suomi/NPP satellite as it took this image was, although on the night side of the planet, nevertheless outside the shadow of the Earth, and radiation from the Sun was able to contaminate the image. Despite this, the lights of Minnesota and Iowa, both the main cities and the smaller towns, are plainly visible. City lights in eastern Wisconsin and Illinois have a more diffuse character because they are being viewed through cirrus clouds from a departing convective complex, as evident in this enhanced 10.7 micrometer imager from 0800 UTC.

VIIRS Day/Night Band from Suomi/NPP satellite

The GOES-R IFR Proabability image from 0801 UTC, above, shows high probabilities of low clouds over north-central Iowa and south-central Minnesota. Surface observations plotted on the image confirm IFR conditions, with low visibilities and low ceilings. In addition, GOES-R Cloud Thickness values in the region are from 800 and 1000 feet thick. It is interesting that the Day/Night band can view the city lights through a low stratus deck that is hundreds of feet thick.

It is very difficult to distinguish between low stratus and clear regions in the stray light zone. That task is somewhat easier when there is no stray light, as shown in this image over the southern United States: In low light conditions, such as during a New Moon, low clouds have a smudgey appearance, but that signature is overwhelmed in the stray light zone. How thick does a cloud have to be before it is opaque to visible light?

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GOES Sounder Imagery during Filter Wheel Anomaly

The GOES-13 Sounder imagery has shown signatures intermittently over the past 4 days that suggest a Filter Wheel Anomaly is ongoing. The image above is from 0246 UTC on 17 July 2012. Similar events occurred on 16 July (at 0046 and 1446 UTC), on 15 July (at 2346 UTC), on 14 July (at 1946 UTC) and on 13 July (1346, 1846, 2046 and 2146 UTC). The GOES-13 Sounder suffered from Filter Wheel Anomalies in June, as well, as noted here.

As before, when the GOES Sounder Data are degraded by filter wheel anomalies, derived products (such as Total Precipitable Water, or Lifted Index), are also degraded. An example of Total Precipitable Water computed when there are Filter Wheel Anomalies in the data is shown below. The Blended Total Precipitable Water products in AWIPS are unaffected, however (Link), because they rely on GPS data over land.

GOES Sounder DPI Imagery of Total Precipitable Water showing effect of Filter Wheel Anomaly

[Update, 23 July 2012 and 25 July] Sounder anomalies persist, and occurred at 2246 UTC and 2346 UTC on 19 July, at 0346 UTC on 20 July, and 2046 UTC on 22 July; at 0046 UTC, 1446 UTC and 1546 UTC on 24 July; at 0046 UTC, 0146 UTC and 0246 UTC on 25 July; at 0546 UTC and 2346 UTC on 26 July; at 2046 UTC and 2146 UTC on 30 July and at 1847 UTC and 2047 UTC on August 4th.

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Meteosat-9 Saharan Air Layer (SAL) product (click image to play animation)

One of the more pronounced in a series of pulses of Saharan dust moving westward across the Atlantic Ocean was seen during the 14 July – 16 July 2012 time period. The Meteorsat-9 “split window” Saharan Air Layer (SAL) tracking product (above; click image to play animation) displayed a very strong signal of a large area of SAL dust (yellow to orange to dark red color enhancement) approaching the Lesser Antilles and the Greater Antilles islands of the West Indies.

The hazy signature of the dust cloud was also seen during the daytime hours on Meteosat-9 pseudo-natural color images  Red/Green/Blue (RGB) images (below; click image to play animation). A large area of sun glint was prominent over the middle Atlantic Ocean on the 18:00 UTC images, but the dust cloud could always been seen to the west of the sun glint.

Meteosat-9 pseudo natural color imagery product (click image to play animation)

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