GOES-14 begins service as GOES-East

May 23rd, 2013 |
CONUS view of GOES 10.7 µm Longwave Infrared (IR Window) imagery

CONUS view of GOES 10.7 µm Longwave Infrared (IR Window) imagery

At 10:00 UTC on 23 May, GOES-14 imagery started flowing to AWIPS as the GOES-East satellite (as seen in the comparison between the 09:30 and 10:10 UTC IR images above). Work continues on evaluating the status of GOES-13. GOES-14 remains in geostationary orbit at 105.5 West longitude, and GVAR data are being broadcast directly from GOES-14 (not relayed through GOES-13). Updates on GOES-13 — and all satellites — can be found here.

GOES sounder water vapor channel (6.5 µm) imagery from GOES-13 and GOES-14

GOES sounder water vapor channel (6.5 µm) imagery from GOES-13 and GOES-14

Sounder data from GOES-14 are also flowing into AWIPS. The 6.5µm water vapor channel imagery from the GOES Sounder is much cleaner on GOES-14 than on GOES-13, as shown in the image comparison above. Note also that the Sounder footprint is slightly different between GOES-13 (positioned at 75 W) and GOES-14 (positioned at 105.5 W).

GOES-14 0.63 µm visible channel images (click image to play animation)

GOES-14 0.63 µm visible channel images (click image to play animation)

For the first 24 hours or so, users will notice some slight problems with the accuracy of the Image Navigation and Registration (INR), as can be seen in a sequence of GOES-14 0.63 µm visible channel images (above; click image to play animation).

GOES-13 outage

May 22nd, 2013 |
Last GOES-13 10.7 µm image before outage

Last GOES-13 10.7 µm image before outage

GOES-13 suffered an anomaly overnight: the satellite is no longer pointed towards the Earth for as yet unknown reasons. The anomaly started at 03:40 UTC on 22 May, and at 04:29 UTC, GOES-15 (GOES-West) began a 30-minute full disk scan schedule.

Last GOES-13 10.7 µm images before outage

Last GOES-13 10.7 µm images before outage

Successive images from just before the anomaly (above), at nominal times of 03:15 UTC and 03:32 UTC, are shown. There is a large navigation offset (~200 km) apparent in the right panel, which panel shows the last scanned image from GOES-13 before the major anomaly. The offset is also apparent in the image at the top of the page (Look, for example, at Cuba, or in the northwest corner of the image)

GOES-14, in standby mode at 105.5 W longitude, has been activated; the first images from GOES-14 will be available at 05:00 UTC 23 May. There are no plans now to move GOES-14 from its current position. In the meantime, GOES engineers are working on a solution to GOES-13’s problems. An update from the Environmental Satellite Processing Center (ESPC) is scheduled for around Noon eastern time (see NOAA NESDIS GOES Special Bulletins). Note that GOES-14 data will *not* be relayed via GOES-13 — so ground station users will need to reposition their antennas to receive GOES-14 direct readout data.

In addition, GOES-12 (GOES-South America) continues to give coverage from its position over 60 W. Full-disk imagery is available every three hours, and routine sampling (both Imager and Sounder) continues and is available here.

— Note to NWS AWIPS Users —

GOES-15 (GOES-West) full-disk coverage

GOES-15 (GOES-West) full-disk coverage

With the temporary loss of GOES-13 (GOES-East), the GOES-15 (GOES-West) satellite has been placed into Full Disk scan mode, which only provides imagery over CONUS every 30 minutes — and the quality of the imagery degrades over the eastern US (above), due to the very large view angle from GOES-15 (which is located at 135 West longitude). Parallax error is also greatly increased.

During such an outage of geostationary satellite data, imagery from polar-orbiting satellite instruments (such as Terra and Aqua MODIS, Suomi NPP VIIRS, and POES AVHRR) can be used when available to help fill in temporal data gaps, and also provide a much more detailed image in terms of spatial resolution (and with a lack of a large parallax error).  The animation below covers the time period from 04:00 UTC to 11:00 UTC, showing the GOES-15 IR imagery at 30 minute intervals with the insertion of IR images from MODIS, VIIRS, and AVHRR when available. You can immediately see the value of the higher spatial resolution provided by the polar-orbiting satellite data.

Animation of GOES-15 IR images, with available polar-orbiter satellite IR images inserted

Animation of GOES-15 IR images, with available polar-orbiter satellite IR images inserted

A direct comparison of GOES-15 and Suomi NPP VIIRS IR imagery around 07:00 UTC (below) again shows the better detail provided by the higher spatial resolution of VIIRS (along with a lack of parallax error) for severe thunderstorms that were producing large hail and damaging winds across parts of the lower Mississippi Valley region.

Comparison of 07:03 UTC Suomi NPP VIIRS IR image and 07:00 UTC GOES-15 IR image

Comparison of 07:03 UTC Suomi NPP VIIRS IR image and 07:00 UTC GOES-15 IR image

In addition, the availability of a Day/Night Band on the VIIRS instrument can provide a “visible image at night”, which can be helpful for locating important  features such as convective overshooting tops and low-level cloud edges (below).

Suomi NPP VIIRS IR and Day/Night Band images

Suomi NPP VIIRS IR and Day/Night Band images

Imagery and products from AVHRR, MODIS, and VIIRS are available in AWIPS via LDM subscription.

Moore, Oklahoma tornado

May 20th, 2013 |
GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images (click image to play animation)

GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images (click image to play animation)

A devastating tornado struck Moore, Oklahoma just after 20:00 UTC or 3:00 PM local time on 20 May 2013, causing extensive (EF4 to EF5) damage and at least 24 fatalities. McIDAS images of GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible channel data (above; click image to play animation; also available as a QuickTime movie) showed the line of rapidly-developing thunderstorms over southern and central Oklahoma during the early afternoon hours — Moore is located about halfway between Oklahoma City (OKC) and Norman (OUN). Earlier in the day the GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode (providing images as frequently as every 5-10 minutes), while the GOES-15 satellite was placed into Super Rapid Scan Operations (SRSO) mode (providing bursts of imagery at 1-minute intervals) after 20:15 UTC. According to the preliminary NWS damage survey, the tornado began around 19:45 UTC just west of Newcastle, and ended around 20:35 UTC just east of Moore.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

An AWIPS comparison of 1-km resolution Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images about an hour before the tornado arrived in Moore (above) revealed the presence of shadowing from overshooting tops and cloud-top IR brightness temperatures as cold as -68º C. About 30 minutes prior to the Moore tornado, a comparison of 1-km resolution Aqua MODIS 0.65 µm visible channel and 11.0 µm IR channel images (below) again indicated signatures of vigorous overshooting tops, with cloud-top IR temperatures as cold as -76º C.

Aqua MODIS 0.65 µm visible channel and 11.0 µm IR channel images

Aqua MODIS 0.65 µm visible channel and 11.0 µm IR channel images

Comparisons of the 1-km resolution VIIRS 11.45 µm IR and MODIS 11.0 µm IR images with their corresponding 4-km resolution GOES-13 10.7 µm IR images (below)  demonstrated the value of higher spatial resolution to aid in the earlier and more accurate detection of the cold cloud-top IR brightness temperatures values associated with these rapidly-developing convective cells. There were significant differences in the magnitude of the coldest cloud-top IR brightness temperatures with the more northerly cell that spawned the Moore tornado:  -68 C on VIIRS vs -51 C on GOES, and -76 C on MODIS vs -62 C on GOES. The northwestward shift in the location of features on the GOES-13 images was due to parallax.

Comparison of 1-km resolution VIIRS 11.45 µm IR image and corresponding 4-km resolution GOES-13 10.7 µm IR image

Comparison of 1-km resolution VIIRS 11.45 µm IR image and corresponding 4-km resolution GOES-13 10.7 µm IR image

Comparison of 1-km resolution MODIS 11.0 µm IR image and corresponding 4-km resolution GOES-13 10.7 µm IR image

Comparison of 1-km resolution MODIS 11.0 µm IR image and corresponding 4-km resolution GOES-13 10.7 µm IR image

A 250-meter resolution Aqua MODIS true-color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below; viewed using Google Earth) shows a closer view of the northernmost cell that produced the Moore tornado, along with hail as large as 3.25 inches in diameter (SPC storm reports).

MODIS true-color Red/Green/Blue (RGB) ima

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

GOES-13 sounder Convective Available Potential Energy (CAPE) derived product images (below; click image to play animation) showed how the atmosphere rapidly destabilized during the day, with CAPE values in excess of 5000 J/kg (lighter purple color enhancement) at 18:00 UTC east of the stationary frontal boundary just prior to convective development.

GOES-13 sounder CAPE derived product images (click image to play animation)

GOES-13 sounder CAPE derived product images (click image to play animation)

Cloud Top Temperature retrievals created using data from the IASI, CrIS, and AIRS polar-orbiting sounder instruments (below; courtesy of Elizabeth Weisz and Nadia Smith, CIMSS) showed the rapid trend in cloud-top cooling during the 15:56-19:35 UTC timeframe.

Cloud Top Temperature retrievals from IASI, CrIS, and AIRS sounder instruments

Cloud Top Temperature retrievals from IASI, CrIS, and AIRS sounder instruments

 

Flooding along the Yukon River in Alaska

May 20th, 2013 |
Suomi NPP VIIRS 1.61 µm near-IR "snow/ice channel" images

Suomi NPP VIIRS 1.61 µm near-IR “snow/ice channel” images

A comparison of AWIPS images of Suomi NPP VIIRS 1.61 µm “snow/ice discrimination channel” data from 19 May and 20 May 2013 (above) revealed the areal extent of flooding along the Yukon River upstream of the Fort Yukon (station identifier PFYU) area in northeastern Alaska. Both ice and water are strong absorbers at the 1.61 µm wavelength, so they appear very dark on the images. The flooding along the Yukon River began as a surge of ice and water moved through the Eagle, Alaska (station identifier PAEG) area on 17 May, then continued downstream to produce major flooding in the Circle, Alaska area on 19 May (Circle is located about halfway between PAEG and PFYU). An ice jam had formed about 12 miles upstream of Fort Yukon, which then impounded the flow of ice and water that had flooded Circle, leading to the increased flooding seen upstream of Fort Yukon on 20 May.

A comparison of Suomi NPP VIIRS 0.64 µm visible channel, 0.86 µm “land/water discrimination channel”, and 1.61 µm “snow/ice discrimination channel” at 20:52 UTC on 20 May (below) showed how the 0.86 µm and 1.61 µm images can be used to identify the darker flooded portions of the Yukon River that are not apparent on the 0.64 µm visible image.

Suomi NPP VIIRS 0.64 µm visible channel, 0.86 µm "land/water" channel, and 1.61 µm "snow/ice channel" images

Suomi NPP VIIRS 0.64 µm visible channel, 0.86 µm “land/water” channel, and 1.61 µm “snow/ice channel” images