Halloween Moon on GOES-13 imagery

October 31st, 2010

GOES-13 0.63 µm "visible channel" image

GOES-13 0.63 µm "visible channel" image

Steve Nazar wrote in an email:

“For the first time, I’ve seen Luna in a GOES photo! Maybe this is commonplace, but I’ve only seen it this once in roughly 20 years of looking at your site. Luna was in GOES East at 2345H Oct 31, and in no others in the sequence. It showed just above the horizon over Vancouver Island, in all wavelengths.”

The GOES-13 (GOES East) 0.63 µm “visible channel” image (above) did indeed show a crescent of the Moon being illuminated just off the Earth’s horizon late in the day on 31 October 2010. A wide band of cloudiness moving over much of British Columbia and the Pacific Northwest was associated with a frontal boundary and an upper level trough of low pressure over that region . As it turns out, the Moon can actually be seen on GOES images a handful of times every year, depending on the viewing angle of the satellite in relation to the position of the Moon (for example, see http://cimss.ssec.wisc.edu/goes/blog/archives/2106).

GOES-13 3.9 µm "shortwave IR channel" image

GOES-13 3.9 µm "shortwave IR channel" image

The GOES-13 3.9 µm “shortwave IR image (above) showed that the illuminated portion of the Moon exhibited very hot IR brightness temperatures (dark black enhancement) — the maximum value indicated using McIDAS was 340 K. The very hot sunlit surface of the moon can actually reach temperatures of 383 K / +110º C / +230º F, while surface temperatures on the very cold “dark” side of the moon can fall to 93 K / -180º C / -292º F.

GOES-13 6.5 µm "water vapor channel" image

GOES-13 6.5 µm "water vapor channel" image

The GOES-13 6.5 µm “water vapor channel” image (above) showed a rather interesting pattern of banded gradients — this was due to the fact that the water vapor channel detectors are designed to sample much colder features, so the extreme heat of the illuminated moon surface caused a supersaturation or “roll-over” from hot (black) to cold (white).

GOES-13 10.7 µm "IR window channel" image

GOES-13 10.7 µm "IR window channel" image

The GOES-13 10.7 µm “IR window channel” image (above) also displayed very hot IR brightness temperatures across the sunlit portion of the Moon (as high as 330.5 K).

An animation of these 4 images is shown below:

GOES-13 visible, shortwave IR, water vapor, and IR window channels

GOES-13 visible, shortwave IR, water vapor, and IR window channels

MODIS imagery over Colorado

October 27th, 2010
MODIS 0.65 µm visible channel + 2.1 µm "snow/ice channel" images

MODIS 0.65 µm visible channel + 2.1 µm "snow/ice channel" images

Snow cover was beginning to accumulate into the 12-24 inch range at some locations across the higher terrain of the Rocky Mountains in Colorado on 27 October 2010. While the snow-covered mountains appeared as brighter white features in contrast to the surrounding bare ground areas on AWIPS images of the MODIS 0.65 µm visible channel data, a comparison with the corresponding MODIS 2.1 µm “snow/ice channel” image (above) showed how it was possible to easily discriminate between areas with deep snow cover (which appeared as much darker features on the snow/ice image) and supercooled water droplet clouds (which appeared as brighter white features on the snow/ice image). The large area of cirrus clouds covering the northeastern corner of the image also appeared as a slightly darker shade of gray on the snow/ice image, due to their ice crystal composition.

Another method to easily discriminate between deep snow cover and supercooled water droplet clouds is to use a false color Red/Green/Blue (RGB) image (below), generated using the MODIS visible channel as the Red component and the MODIS snow/ice channel as the Green and Blue components of the image. Deep snow cover then appears as darker red features, in contrast to supercooled water droplet clouds which appear as brighter white features on the image. Again, the large area of cirrus clouds covering the northeastern corner of the image also appeared as a lighter shade of red on the RGB image, due to their ice crystal composition.

MODIS false color Red/Green/Blue (RGB) image

MODIS false color Red/Green/Blue (RGB) image

It can also be informative to compare the MODIS 3.7 µm shortwave IR image to the corresponding MODIS 11.0 µm IR window image (below). Some of the cloud features over northwestern Colorado were exhibiting 11.0 µm IR window brightness temperatures of -20º C and colder (cyan to blue color enhancement), suggesting that they could possibly be getting cold enough for glaciation to occur — however, these cloud features still appeared as darker features on the 3.7 µm shortwave IR image, indicating a strong component of reflection of incident solar radiation off of supercooled water droplets.

MODIS 3.7 µm shortwave IR image + MODIS 11.0 µm IR window image

MODIS 3.7 µm shortwave IR image + MODIS 11.0 µm IR window image

One of the more interesting comparisons is between the 0.65 µm MODIS visible channel image and the corresponding MODIS 6.7 µm water vapor image (below). Note the presence of widespread mountain waves to the lee of the higher terrain of the Rocky Mountains on the water vapor image — the vast majority of these waves were in cloud-free air according to the visible channel image. Such mountain wave signatures on water vapor imagery can indicate regions where clear air turbulence might be likely.

MODIS 0.65 µm visible channel image + MODIS 0.67 µm water vapor image

MODIS 0.65 µm visible channel image + MODIS 0.67 µm water vapor image

CIMSS has been making MODIS imagery and products available in AWIPS format to National Weather Service forecast offices as a part of the GOES-R Proving Ground project.

Powerful Great Lakes Cyclone

October 26th, 2010
GOES-13 6.5 µm water vapor imagery + surface analyses + storm reports

GOES-13 6.5 µm water vapor imagery + surface analyses + storm reports

An unusually large and strong mid-latitude cyclone rapidly intensified over the western Great Lakes region on 26 October 2010 (see HPC 18 UTC surface analysis and 22 UTC SPC Watches, Warnings, and Advisories). AWIPS images of GOES-13 6.5 µm water vapor channel data with overlays of surface analyses and SPC storm reports (above) showed a well-defined dry slot (yellow color enhancement) wrapping into the southern and eastern quadrants of the storm. Very strong surface wind gusts (NWS Milwaukee | NWS Green Bay | HPC) associated with this cyclone were reported in Wisconsin (79 mph at Sherwood), the Upper Peninsula of Michigan (70 mph at Point Aux Barques), South Dakota (70 mph at Union Center), and Minnesota (65 mph at Mehurin).

AWIPS Northern Hemisphere composite water vapor images covering the period 23-27 October 2010 (below; also available as a QuickTime movie) revealed the large amount of jet stream energy that was approaching the Lower 48 states from the central and eastern Pacific Ocean during the days leading up to the development of the strong Great Lakes cyclone.

Northern Hemisphere composite water vapor images (23-27 October 2010)

Northern Hemisphere composite water vapor images (23-27 October 2010)

One notable aspect of this storm is that it set new all-time lowest barometric pressure readings for the states of Wisconsin and Minnesota (which were the equivalent to those that would be seen in a Category 3 hurricane):

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE DULUTH MN
1227 PM CDT WED OCT 27 2010

…LOW PRESSURE RECORDS BROKEN ON OCTOBER 26 2010…

THIS IS A PRELIMINARY STATEMENT ON THESE PRESSURE RECORDS. HERE IS WHAT WE KNOW SO FAR ABOUT THE LOW PRESSURE RECORDS SET ON OCTOBER 26TH:

A FEW OF THE RECORDS HAVE BEEN RECALCULATED TO ADJUST FOR TRUE MEAN SEA LEVEL PRESSURE. SOME OF THE PREVIOUS VALUES WERE CALCULATED USING A STANDARD ATMOSPHERE ASSUMPTION /THE ALTIMETER SETTING AT THE STATION/. THE VALUES IN MILLIBARS ARE THE ONES THAT WILL BE MORE EXACT.

AN UNUSUALLY INTENSE LOW AFFECTED THE STATE OF MINNESOTA. AT 513 PM CDT…THE AUTOMATED WEATHER OBSERVING SYSTEM AT BIGFORK MINNESOTA RECORDED A 955.2 MILLIBAR /28.21 INCHES/ PRESSURE. THIS BREAKS THE ALL TIME MINNESOTA STATE RECORD FOR THE LOWEST OBSERVED PRESSURE.

THE PREVIOUS RECORD WAS 962.7 MB SET ON NOVEMBER 10 1998 AT ALBERT LEA AND AUSTIN IN SOUTHERN MINNESOTA. THE RECORD WAS INITIALLY BROKEN SHORTLY AFTER 10 AM AS THE LOW PASSED BY AITKIN MINNESOTA. HOWEVER…THE LOW CONTINUED TO INTENSIFY INTO THE AFTERNOON OVER NORTH CENTRAL MINNESOTA WHERE THE RECORD PRESSURE READING WAS ULTIMATELY ESTABLISHED AT BIGFORK.

.DULUTH…THE LOW PRESSURE RECORD AT DULUTH WAS SET AT 1115 AM WITH A PRESSURE OF 960.2 MILLIBARS /28.35 INCHES/. THE PREVIOUS RECORD WAS 964.3 MILLIBARS WHICH OCCURRED ON NOVEMBER 10 1998.

.INTERNATIONAL FALLS…THE LOW PRESSURE RECORD AT INTERNATIONAL FALLS WAS SET AT 345 PM WITH A PRESSURE OF 956.0 MILLIBARS /28.23 INCHES/. THE PREVIOUS RECORD WAS 971.9 MILLIBARS ON OCTOBER 10 1949.

.WISCONSIN…THE LOW PRESSURE RECORD FOR THE STATE OF WISCONSIN WAS SET IN SUPERIOR AT 1115 AM WITH A PRESSURE OF 961.3 MILLIBARS /28.39 INCHES/. THE PREVIOUS RECORD WAS 963.43 MILLIBARS /28.45 INCHES/ WHICH OCCURRED AT GREEN BAY ON APRIL 3 1982.

$$

LAMERS

A comparison of 1-km resolution MODIS 6.7 µm and 4-km resolution GOES-13 6.5 µm water vapor images (below) demonstrated the advantage of higher spatial resolution for detecting subtle wave features that could be indicators of possible turbulence. In this case, the MODIS water vapor image did indicate the presence of a subtle packet of waves aloft over central Lake Michigan — and there were pilot reports of moderate turbulence very near these wave features at 20,000 and 23,000 feet. Satellite-derived atmospheric motion vectors also showed that the axis of highest jet stream winds (134 knots at 300 hPa) was located along the far eastern edge of the dry slot on the water vapor image.

MODIS vs GOES-13 water vapor images + turbulence reports + satellite winds

MODIS vs GOES-13 water vapor images + turbulence reports + satellite winds

AWIPS images of 1-km resolution POES AVHRR 10.8 µm IR data with overlays of surface analyses (below) showed the evolution of the deepening storm, which exhibited very detailed cloud top structure on many of the IR images.

POES AVHRR 10.8 µm IR images + surface analyses

POES AVHRR 10.8 µm IR images + surface analyses

To get a feel for the overall size of the cyclone, a GOES-13 false color full disk image is shown below (courtesy of Rick Kohrs, SSEC).

GOES-13 false color full disk image (14:15 UTC, 27 November)

GOES-13 false color full disk image (14:15 UTC , 27 November)

Super Typhoon Megi

October 18th, 2010
MTSAT-1R 0.68 µm visible channel images

MTSAT-1R 0.68 µm visible channel images

MTSAT-1R 0.68 µm visible channel images (above) tracked the eye of Super Typhoon Megi making landfall across the northern portion of the island of Luzon in the Philippines on 17-18 October 2010.

The Morphed Integrated Microwave Imagery at CIMSS (MIMIC) product (below) showed the well-defined eye of Megi prior to making landfall, along with the effect that the rugged terrain of Luzon had on the typhoon before it later emerged into the South China Sea.

Morphed Integrated Microwave Imagery at CIMSS (MIMIC)

Morphed Integrated Microwave Imagery at CIMSS (MIMIC)

A Terra MODIS 11.0 µm IR image (below; zoomed-in version) revealed the eye and surrounding concentric eyewall structure of Megi at 02:30 UTC on 19 October — the coldest IR brightness temperature seen at that time was -82º C (purple color enhancement) to the south of the eye.

Terra MODIS 11.0 µm IR image

Terra MODIS 11.0 µm IR image