GOES-11, GOES-13, GOES-15, and MODIS water vapor channel images

A comparison of 8-km resolution GOES-11 6.7 µm water vapor channel, 4-km resolution GOES-13 and GOES-15 6.5 µm water vapor channel, and 1-km resolution Aqua MODIS 6.7 µm water vapor channel images (above) demonstrated how differences in satellite viewing angle as well as differences in satellite sensor spatial resolution have an impact in being able to resolve the structure and areal coverage of small-scale features such as the mountain waves that existed across much of southeastern Colorado and northeastern New Mexico around 19:45 UTC on 12 November 2011.

There were a number of pilot reports of moderate to severe turbulence aloft across the region – and at the surface, wind gusts as high as 115 mph were reported. As can be seen in a comparison of 1-km resolution MODIS 0.65 µm visible channel and MODIS 6.7 µm water vapor channel images (below), many of the mountain waves were located in cloud-free areas — this highlights the value of water vapor channel imagery for identifying such regions of potential aircraft turbulence.

MODIS 0.65 µm visible channel + MODIS 6.7 µm water vapor channel images

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MTSAT-1R 6.7 µm water vapor channel images

McIDAS images of MTSAT-1R 6.7 µm water vapor channel data (above) showed an intense extratropical cyclone that was moving toward the Bering Sea region during the 07 November – 08 November 2011 time frame. Of particular interest was the presence of a very warm/dry (dark black) circular region within the dry slot sector of the developing cyclone, which could have been associated with a strong potential vorticity anomaly.

A color-enhanced comparison of MTSAT-1R and GOES-11 6.7 µm water vapor channel data (below; click image to play animation) demonstrated the difference that satellite viewing angle (MTSAT looking from the west; GOES-11 looking from the east) and satellite sensor spatial resolution (the MTSAT-1R water vapor channel is “4 km” at nadir, while the GOES-11 water vapor channel is “8 km” at nadir) play in the ability to resolve such potentially important dynamical features. The core of the aforementioned MTSAT-1R dry feature moved directly over Shemya Island around 12:00 UTC on 08 November (MODIS IR image with surface analysis), where a surface wind gust of 83 mph was recorded at Shemya Air Force Base. Then, once the storm began to move northward over the Bering Sea, a more “curved banding” structure was seen on water vapor imagery as the cyclone began to wrap filaments of dry air around the deepening storm center. Although the sun angle was low, some of the “banding structure” could be seen in GOES-11 0.65 µm visible channel images.

MTSAT-1R (left) and GOES-11 (right) 6.7 µm water vapor channel images (click image to play animation)

While the dry slot features began to lose their definition in the geostationary MTSAT-1R and GOES-11 water vapor images (in part due to the upward shift in the peak of the water vapor channel weighting function with increasing satellite viewing angle), a direct overpass of the Aqua satellite around 23:45 UTC on 08 November provided a nice view using the 6.7 µm water vapor channel on the MODIS instrument (below). Using the MODIS imagery, good dry slot structure could be seen, even after the storm had moved northward over the Bering Sea.

Aqua MODIS 6.7 µm water vapor channel image

A sequence of AWIPS images of 1-km resolution MODIS 11.0 µm and POES AVHRR 12.0 µm InfraRed data (below; click image to play animation) showed the storm at various phases as it was rapidly deeping during its northward trek over the Bering Sea.

MODIS 11.0 µm and POES AVHRR 12.0 µm InfraRed images (click image to play animation)

This ended up being one of the strongest Bering Sea storms on record — the winds exceeded hurricane force across a very expansive area, producing high seas and major coastal flooding and beach erosion along parts of western Alaska. At the Tin City Airways Facility Sector (located near the western tip of the Seward Peninsula), they reported sustained winds of 72 mph with gusts to 85 mph — and the minimum altimeter air pressure was 28.46 inches. A peak gust of 89 mph was reported nearby at Wales. As the storm moved over St, Lawrence Island, minimum altimeter air pressure readings were 28.21 inches and 28.28 inches at Gambell and Savoonga, respectively.

The entire evolution of the storm during the 08-09 November time period can be seen on an animation of 15-minute interval GOES-11 10.7 µm IR images (below; click image to play animation).

15-minute interval GOES-11 10.7 µm IR images (click image to play animation)

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EUMETSAT Meteosat-9 10.8 µm IR images

A sequence of EUMETSAT Meteosat-9 10.8 µm IR images at 6-hour intervals (above) showed the development of an unusual tropical cyclone over the western Mediterranean Sea during the 06 November – 08 November 2011 time period.

The tropical cyclone was designated “01M” in a bulletin issued by NOAA/NESDIS Satellie Analysis Branch at 18:19 UTC on 07 November:

Wind speeds were estimated to have reached 45 knots according to various satellite analysis techniques.

Shown below is a comparison of EUMETSAT Meteosat-9 0.64 µm visible channel images at 12:00 UTC on 07 November and 08 November.

EUMETSAT Meteosat-9 0.64 µm visble channel images at 12:00 UTC on 07 and 08 November

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GOES-15 10.7-micrometer image at new 'sub-CONUS' scale

A new scanning schedule that adds more sectors is being followed for GOES-15 as the satellite drifts westward towards 135 W. When GOES-15 becomes the new GOES-West, replacing GOES-11 (planned to occur on December 6th), the augmented scanning schedule will become operational, offering 1 or 2 additional scans per hour of the Continental United States (at the so-called ‘sub-conus scale’ depicted here). There images scans start at 11 and 41 minutes past each hour (except when full-disks are taken every three hours, in which case only the image at 41 minutes past the hour is produced). Visible image sizes are 2400×4800 pixels; infrared images sizes are 600×1200.

This image shows the current operational GOES-West imager scanning schedule. Here is the augmented schedule. Note the addition of small images just before the nn:15 and nn:45 images. Because GOES-15 is moving, the geographic coverage for the sub-CONUS imagery is not yet where it will be when GOES-15 is on station at 135 W Longitude.

Recall that GOES-15 has improved water vapor imagery resolution over GOES-11. (Link). In addition, the 12-micrometer channel on GOES-11 will be replaced by a 13.3 micrometer channel on GOES-15. In addition, the visible channel will subtly shift to a channel with a narrower response with a peak at 0.63 micrometers.

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