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 1214 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 (NWS Wilmington NC summary). McIDAS images of EUMETSAT Meteosat-3 Infrared (11.5 µm) channel images (above) 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 (13 March), a larger-scale view of Meteosat-3 Infrared (11.5 µm) images (below) 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 corresponding large-scale view of Meteosat-3 Water Vapor (6.4 µm) images (below) 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 GOES-7 Visible (0.65 µm) image at 18:01 UTC or 1:01 PM Eastern Time on 13 March (below) showed several interesting 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 (click to enlarge)

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 sum, 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

GOES-15 replaces GOES-11 as the operational GOES-West satellite

December 6th, 2011 |

At 15:46 UTC on 06 December 2011, GOES-15 replaced GOES-11 as the operational GOES-West satellite. GOES-11 (launched in 2000, and operational since 2006) was one of the older GOES-I/J/K/L/M series of satellites (GOES-8/9/10/11/12), while GOES-15 (launched in 2010; Post Launch Test) is one of the newer GOES-N/O/P series of satellites (GOES-13/14/15) — so there are some important differences that users of the new GOES-15 imagery should be aware of:

  1. Improved water vapor channel (Imager channel 3)
  2. Slightly different visible channel (Imager chanel 1)
  3. 13.3 µm IR (Imager channel 6) replaces the 12.0 µm  IR (Imager channel 5)
  4. Improved Image Navigation and Registration (INR)
  5. Shorter image outages during Spring and Fall season “eclipse periods”
  6. Less noise on many of the Sounder channels
GOES-11 vs GOES-15 Imager water vapor channel data as the source for GOES-West

GOES-11 vs GOES-15 Imager water vapor channel data as the source for GOES-West

The improvement made to the GOES-15 Imager instrument water vapor channel is likely the most important change that operational users will notice. In the sequence of AWIPS images above, the first 3 images are using the 8-km resolution GOES-11 6.7 µm channel as the source for GOES-West water vapor imagery, while the final 3 images use the 4-km resolution GOES-15 6.5 µm channel. Note the change to slightly warmer/drier water vapor brightness temperatures (brighter yellow color enhancement) after the changeover to GOES-15 — this in part due to the fact that the spectral response function of the 4-km resolution water vapor channel on GOES-12 and beyond is much wider than that of the 8-km resolution water vapor channel on GOES-8 through GOES-11. In addition, notice that the north-south “seam” joining the GOES-West and GOES-East water vapor channel images disappears, since the characteristics of the water vapor channels are now identical on those two satellites.

In the sequence of AWIPS images below, the first 2 images are using the GOES-11 Sounder instrument 6.5 µm channel as the source for GOES-West water vapor imagery, while the final 2 images use the GOES-15 Sounder 6.5 µm channel. Note the improvement in noise seen in the Sounder instrument water vapor images after the changeover to GOES-15. Since the 3 GOES Sounder water vapor channels are a component of the GOES Sounder Total Precipitable Water derived product imagery, the quality of that product should also improve.

GOES-11 vs GOES-15 Sounder 6.5 µm water vapor channel data as the source for GOES-West

GOES-11 vs GOES-15 Sounder 6.5 µm water vapor channel data as the source for GOES-West

In terms of the visible imagery, a comparison using GOES-11 (the first 3 images) vs GOES-15 (the final set of 3 images) Imager visible channel data is seen below (during a test on 29 November). Immediately obvious is the fact that the GOES-15 visible channel imagery appears “brighter” than the GOES-11 visible channel imagery — this is due to the fact that the performance of the GOES visible detectors degrades over time. The 0.63 µm visible channel on GOES-15 is also slightly different than the 0.65 µm visible channel on GOES-11, as is discussed in the “GOES-13 is now the operational GOES-East satellite” blog post. GOES-15 is similar to GOES-13, since it is part of the GOES-N/O/P series of spacecraft.

Using GOES-11 vs GOES-15 as the source for GOES-West visible channel images

Using GOES-11 vs GOES-15 as the source for GOES-West visible channel images

One of the benefits of GOES-15 is improved Image Navigation and Registration (INR), which leads to less image-to-image “wobble” when viewing an animation. The improved GOES-15 INR is quite evident when compared to GOES-11 for this blowing dust case on 27 November (below; click image to play animation).

GOES-11 0.65 µm and GOES-15 0.63 µm visible images (click image to play animation)

GOES-11 0.65 µm and GOES-15 0.63 µm visible images (click image to play animation)

A comparison of the GOES-15 0.63 µm visible channel, the 10.7 µm “IR window” channel, and the 13.3 µm “CO2 absorption” IR channel (below) shows that high cloud features will show up with more clarity on the 13.3 µm images — by examining the weighting function of the 13.3 µm IR channel, it can be seen that this CO2 absorption channel samples radiation from a much deeper, much higher altitude than the standard 10.7 µm IR window channel.

GOES-15 0.63 µm visible channel, 10.7 µm IR channel, and 13.3 µm IR channel images

GOES-15 0.63 µm visible channel, 10.7 µm IR channel, and 13.3 µm IR channel images

The 13.3 µm “CO2 absorption” IR channel is also used for the creation of derived products such as Cloud Top Pressure. An example of a combined GOES-15 (GOES-West) + GOES-13 (GOES-East) Cloud Top Pressure product is shown below (courtesy of Tony Schreiner, CIMSS).

GOES-15 + GOES-13 Cloud Top Pressure product

GOES-15 + GOES-13 Cloud Top Pressure product

An example of the value of having larger batteries onboard the GOES-13/14/15 spacecraft during eclipse periods can be seen below, as Hurricane Ike was making landfall along the Texas coast in September of 2008. During the approximately 3 hour image outage from GOES-12 during the eclipse period (when the satellite was in the Earth’s shadow, and the solar panels could not generate the power necessary to operate the GOES imager and GOES sounder instrument packages), GOES-13 IR images continued to be available — and these GOES-13 images showed a strong spiral band that was in the process of intensifying and moving inland along the far northeastern Texas and far southwestern Louisiana coastlines.

GOES-12 vs GOES-13 IR images (Hurricane Ike making landfall)

GOES-12 vs GOES-13 IR images (Hurricane Ike making landfall)

Additional information can be found on the VISIT training lesson “GOES-15 Becomes GOES-West“.

HISTORICAL NOTE: GOES-15 became GOES-West on the 45th anniversary of the launch of ATS-1 on 06 December 1966. ATS-1 was the first meteorological satellite to provide geostationary images — an example of an early ATS-1 visible image is seen below, and QuickTime movies are available which show animations of some of the early ATS-1 images.

ATS-1 visible image (11 December 1966)

ATS-1 visible image (11 December 1966)

35-year anniversary of the sinking of the Edmund Fitzgerald

November 10th, 2010 |
48-hour simulated IR satellite imagery from the CRAS model (9-11 Nov 1975)

48-hour simulated IR satellite imagery from the CRAS model (9-11 Nov 1975)

Today marks the 35-year anniversary of the powerful Great Lakes storm that was responsible for the sinking of the SS Edmund Fitzgerald (on 10 November 1975). Since the first operational geostationary weather satellites (SMS-1 and SMS-2) were relatively new back in 1975, the CIMSS Regional Assimilation System (CRAS) model was utilized to generate synthetic IR satellite images to provide an idea of what the satellite imagery might have looked like for this intense storm (CRAS model surface winds). A 48-hour sequence of synthetic IR images (above) shows the evolution of the model-derived cloud features at 1-hour intervals.

As part of the CIMSS involvement in GOES-R Proving Ground activities, CRAS synthetic forecast satellite imagery (IR and Water Vapor channels, below) is currently being made available in an AWIPS format for interested NWS forecast offices to add to their local AWIPS workstations (via LDM subscription). For more information, see the CRAS Imagery in D-2D site. VISIT training is also available on the topic.

CRAS forecast IR imagery in AWIPS

CRAS forecast IR imagery in AWIPS

CRAS forecast water vapor imagery in AWIPS

CRAS forecast water vapor imagery in AWIPS