The Memphis Derecho of July 22 2003

July 31st, 2013
GOES-12 10.7 µm IR imagery (Click Image to play animation)

GOES-12 10.7 µm IR imagery (Click Image to play animation)

On the morning of July 22, 2003, a strong derecho moved through metropolitan Memphis, TN, with winds exceeding hurricane-force. The most significant impact of this storm was a loss of power caused in part by the many trees that were downed by the winds. The Storm Report for the day from the Storm Prediction Center shows a cluster of wind reports in and around Memphis and Shelby County. The National Weather Service office in Memphis produced a report on this event that includes radar imagery and a discussion of surface and upper-air observations. More information on this derecho is here. What do satellite data show for this event?

The animation of 10.7 µm imagery, above, shows the development of convection in southeast Kansas and northwest Arkansas that then moves eastward into the mid-South, hitting Memphis around 1200 UTC. Several overshooting tops are evident as the storms pass near Memphis, with the coldest brightness temperatures at 196K! Past derechosdiscussed on this blog (such as the one that hit the East Coast in 2012) were characterized by a channel of moisture and instability aligned with the storm motion, allowing the propagating thunderstorm complex access to a rich source of moisture and instability. This event in 2003 was no different. GOES-12 Sounder retrievals — during that year, 3×3 fields-of-view were used (versus single pixels now) — of Total Precipitable Water, Convective Available Potential Energy (CAPE) and Lifted Index (LI), show abundant moisture and instability aligned west-to-east across northern Arkansas. CAPE values exceeded 3000 J/kg, Total Precipitable Water was greater than 2 inches, and Lifted Indices were near -10.

GOES-10/GOES-12 Sounder-Derived Total Precipitable Water (3x3 Field of View) (Click Image to play animation)

GOES-10/GOES-12 Sounder-Derived Total Precipitable Water (3×3 Field of View) (Click Image to play animation)

GOES-10/GOES-12 Sounder-Derived Convective Available Potential Energy (CAPE) (3x3 Field of View) (Click Image to play animation)

GOES-10/GOES-12 Sounder-Derived Convective Available Potential Energy (CAPE) (3×3 Field of View) (Click Image to play animation)

GOES-10/GOES-12 Sounder-Derived Lifted Index (3x3 Field of View) (Click Image to play animation)

GOES-10/GOES-12 Sounder-Derived Lifted Index (3×3 Field of View) (Click Image to play animation)

GOES-12 Visible Imagery (Click Image to play animation)

GOES-12 Visible Imagery (Click Image to play animation)

Visible imagery, above, from GOES-12 shows the convection continuing to develop as it moves across the Mississippi River into Memphis. Several Overshooting tops are evident, as well as parallel cloud lines at the cirrus level that are usually associated with turbulence. GOES-10, as GOES-West, was also able to capture the convection as it moved through Memphis (below).

GOES-10 Visible Imagery (Click Image to play animation)

GOES-10 Visible Imagery (Click Image to play animation)

53rd anniversary of the first image from a meteorological satellite

April 1st, 2013

 

TIROS-1 visible image

TIROS-1 visible image

Today marks the 53rd anniversary of the first image from the meteorological satellite TIROS-1, which was available on 01 April 1960 (above). While TIROS-1 was only operational for 78 days, it provided a number of images of the Earth and cloud systems (including the first image of a tropical cyclone, over the South Pacific Ocean on 10 April 1960).

One example that demonstrates how satellite imagery has improved over the past 53 years is a night-time comparison of AWIPS images of Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel  data (below), covering the same general region as shown on the first TIROS-1 image (Maine, and the Canadian Maritime provinces). With ample illumination from the moon (Waning Gibbous phase, 67% of full), the Day/Night Band offered a “visible image at night” which showed such features as the extent of sea ice in the channels between Nova Scotia, Prince Edward Island, and New Brunswick, as well as a series of banded wave clouds associated with an undular bore off the southern coast of Nova Scotia. Subtle details regarding the location and cloud-top IR brightness temperature of overshooting tops could also be seen in the convective clouds off the coast of Maine.

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images

UPDATE: Hat-tip to AccuWeather’s Jesse Ferrell, who found this information which indicates that the TIROS-1 image shown above was actually taken on 02 April 1960! The actual first image from TIROS-1 (taken on 01 April 1960) is shown below (courtesy of Rick Kohrs, SSEC).

The actual first TIROS-1 image (taken on 01 April 1960)

The actual first TIROS-1 image (taken on 01 April 1960)

20-year anniversary of the March 1993 “Storm of the Century”

March 13th, 2013
Meteosat-3 11.5 µm IR channel images (click image to play animation)

Meteosat-3 11.5 µm IR channel images (click image to play animation)

The 12-14 March 1993 “Storm of the Century” (aka “the ’93 Superstorm” or “the Great Blizzard of 1993″) was one of the most significant storms to impact the eastern United States. McIDAS images of EUMETSAT Meteosat-3 11.5 µm IR channel images (above; click image to play animation) showed the storm as it initially began to experience rapid intensification in the Gulf of Mexico on 12 March. At the time, Meteosat-3 was on loan to the US and serving as the “GOES-East” satellite after the failure of GOES-6 in 1989.

On the following day (March 13), a larger-scale view of Meteosat-3 11.5 µm IR channel images (below; click image to play animation) revealed the very large size of the storm as it moved along the Eastern Seaboard of the US. Some highlights of the storm included snowfall amounts as high as 56 inches at Mount LeConte in Tennessee, a wind gust to 144 mph at Mount Washington in New Hampshire, a minimum sea level pressure of 28.28 inches at White Plains in New York, and a post-storm record low temperature of -12º F in Burlington, Vermont.

Meteosat-3 11.5 µm IR channel images (click image to play animation)

Meteosat-3 11.5 µm IR channel images (click image to play animation)

The correspnding large-scale view of Meteosat-3 6.4 µm water vapor channel images (below; click image to play animation) showed the well-defined dry slot and large comma head associated with the storm.

Meteosat-3 6.4 µm water vapor channel images (click image to play animation)

Meteosat-3 6.4 µm water vapor channel images (click image to play animation)

A 0.65 µm GOES-7 visible channel image at 18:01 UTC or 1:01 PM Eastern Time on 13 March (below) showed several interested aspects of the storm, including widespread stratucumulus cloud streets over the Gulf of Mexico and the Atlantic Ocean (due to cold air advection over warmer waters), and also a large cloud arc in the Pacific Ocean south of Mexico, which was the leading edge of a Tehuano mountain gap wind event (see Schultz, et al, 1997). A rope cloud marked the leading edge of the strong cold front, which at the time of the image had plunged as far southward as Honduras in Central America.

GOES-7 0.65 µm visible channel image

GOES-7 0.65 µm visible channel image

Recovering Old GOES Imagery at the UW-Madison SSEC Data Center

January 11th, 2012
GOES-5 Visible Imagery of Hurricane Dennis over Florida in August 1981

GOES-5 Visible Imagery of Hurricane Dennis over Florida in August 1981

The University of Wisconsin served as the official National Satellite Archive for many years before the National Climatic Data Center took over that responsibility. The original operational GOES satellite archive was acquired at the UW-SSEC Data Center onto Sony U-Matic tapes starting in 1978. When these data were converted from U-Matic tapes to IBM 3590 tapes in the mid-1990s through the early 2000s, notable gaps in the satellite record were obvious. (Click here for the image shown above in its originally ingested form).

Recent work at the SSEC Data Center has started to fill in those missing gaps using newly written software that reconciles redundant data and interrogates any anomalies found. Errors that arise from mis-tracking on the U-Matic tape, for example, can be corrected. Similarly, Ingest/signal transmit errors on the U-Matic tape can be rectified. It is important to note that no data are changed, averaged or otherwise manipulated in this processing; rather, data are uncovered by correcting errors in previous processing.

Playback from the U-Matic tapes in the 1990s and 2000s for one image may have occurred multiple times if the Engineer determined that tracking or other errors could be mitigated by adjusting the playback. Usually this involved manual tracking working with an oscilloscope. Present-day recovery involves reprocessing data saved on 3590s (originally pulled from U-Matic tapes), effectively re-ingesting all images, possibly resulting in multiple different ingested images (If an image was played back more than once from the U-Matic tape) that can be merged together into one image that is far more complete than its separate pieces. In a second type of recovery, the playback is redone only once, but smarter ingest software corrects tracking noise, signal noise and tape deterioration. All of the signal (including the noise) was saved onto the 3590s.

More examples of the correction results are shown below. In each case, the original version saved on 3590 is on the left, and the cleaned version is on the right.

About 2800 Mode-A images thought to be completely lost have been recovered by this processing. Nearly 8100 images had corrections to at least 95% of their lines. More than 25000 images had framing errors that were corrected, which errors affected every visible scan in the image. In some, about 2 full years of data have been recovered from the archive by the smarter re-processing.

GOES-1 Visible Imagery from March 1979

GOES-1 Visible Imagery from March 1979

GOES-1 Visible Imagery from May 1979

GOES-1 Visible Imagery from May 1979

GOES-5 Window Channel Imagery from August 1981

GOES-5 IR Window Channel Imagery from August 1981