GOES-13 Sounder Anomalies

September 16th, 2013 |
GOES-13 10.7 µm IR channel images (click unage to play animation)

GOES Sounder DPI Lifted Index from 1300 UTC 15 September

The GOES-13 Sounder has been experiencing an increased number of unexpected scan line lengths. This was originally detected on 1 July 2013 and it has become more common since 12 September 2013. The anomaly is manifest in the data by occasional pixel gaps in all channels of the Sounder images. Some images show only a single gap (and therefore just one missing pixel); other images have several gaps. In the image above, the missing values are the black pixels just off the North Carolina coast (for example), or near the Mississippi River in southwestern Mississippi. Note that missing data only is present in the GOES-13 part of the domain. The GOES-15 signal is clean. The root cause of this error is under investigation. From NESDIS: “No telemetry violations have occurred, and all Sounder filter wheel telemetry data, including Filter wheel currents and period monitors, are within expected values.”

The missing pixels are also present in the real-time Sounder data available at CIMSS at this link. An example from September 15th is shown below. Or, click here for a composite (GOES-13/GOES-15) single-band image.

GOES-13 10.7 µm IR channel images (click unage to play animation)

GOES Sounder DPI Lifted Index from 1300 UTC 15 September

A quick analysis at two times (0246 and 1446 UTC) suggests that prior to 28 August, errors per image were limited to 20 or so pixels. Between 28 August and 9 September, fewer than 100 pixels were affected each hour. Since 10 September, the number of pixels affected in each image has increased one some days to more than 200. There are nearly 64000 pixels in each sounder image, so the number of bad points remains a small percentage of the total.

GOES-15 Navigation Anomalies

September 10th, 2013 |
GOES-15 3.9 µm shortwave IR images on 10 September (click image to play animation)

GOES-15 3.9 µm shortwave IR images on 10 September (click image to play animation)

GOES-15, in service as GOES-West over the Equator at 135 W, has experienced navigation anomalies on each of the past three mornings, September 8, 9 and 10, 2013 (as noted here, for example). Navigation anomalies occur approximately between 0830 and 1100 UTC. GOES Engineers are investigating the source of the anomaly, which can be on the order of 40 km. The animation above is the shortwave infrared from Tuesday 10 September. Animations for 6, 7, 8 and 9 September are below. Note that even the 6 September and 7 September have small navigation issues.

(Update: From SATOPS: NOTE: GOES-15 (West) Image registration (alignment of images to earth grid coordinates) was shifted by approximately 40 kilometers on DOY251 (ed. note: 8 September) from 08:50z to 10:50z and shifted by approximately 25 kilometers on DOY252 & DOY253 (ed. note: 9 and 10 September) from 9:30z to 10:40z. The earth coordinate grid shift was due to a lack of available valid star data for predicting the proper attitude pointing profile around eclipse. The root cause is under investigation.) In other words, the Star Pointer was unable to find enough targets to produce accurate navigation. (Link)

Update, 11 September: The anomalies continued on 11 September, starting after the 0845 UTC image, peaking at the 1000 UTC image, and subsiding by 1045 UTC. Link.

Update, 17 September: Large navigation anomalies were not present overnight.

GOES-15 3.9 µm shortwave IR images on 6 September (click image to play animation)

GOES-15 3.9 µm shortwave IR images on 6 September (click image to play animation)

GOES-15 3.9 µm shortwave IR images on 7 September (click image to play animation)

GOES-15 3.9 µm shortwave IR images on 7 September (click image to play animation)

GOES-15 3.9 µm shortwave IR images on 8 September (click image to play animation)

GOES-15 3.9 µm shortwave IR images on 8 September (click image to play animation)

GOES-15 3.9 µm shortwave IR images on 9 September (click image to play animation)

GOES-15 3.9 µm shortwave IR images on 9 September (click image to play animation)

Morgan Fire northeast of San Francisco

September 9th, 2013 |
GOES-15 3.9 µm shortwave IR images (click image to play animation)

GOES-15 3.9 µm shortwave IR images (click image to play animation)

The Morgan Fire began burning in the Mount Diablo State Park northeast of San Francisco during the afternoon hours on 08 September 2013, which caused the evacuation of dozens of homes near the fire. McIDAS images of 4-km resolution GOES-15 3.9 µm shortwave IR data (above; click image to play animation; also available as a .mp4 file) revealed that the fire “hot spot” (red color enhancement) first appeared on the 21:30 UTC (2:30 PM local time) image. The fire appeared to “settle down” for a few hours after sunset, but then there was an apparent flare-up of the fire from 04:00 – 06:30 UTC.

One thing to note on the GOES-15 shortwave IR animation above is that there was a significant Image Navigation and Registration (INR) anomaly during the 08:45 – 10:41 UTC period. An AWIPS 1-km resolution Suomi NPP VIIRS 3.74 µm shortwave IR image was available at 09:24 UTC (during the GOES-15 INR anomaly) — a comparison of this VIIRS image with the closest available GOES-15 shortwave IR image (below) demonstrates the value of higher spatial resolution VIIRS data to aid in a more accurate determination of the actual fire size and location.

Suomi NPP VIIRS 3.74 µm and GOES-15 3.9 µm shortwave IR images

Suomi NPP VIIRS 3.74 µm and GOES-15 3.9 µm shortwave IR images

Hot spots associated with the ongoing Rim Fire — so far the 3rd-largest fire on record in California — can also be seen about 100 miles to the east-southeast.

GOES-12 is retired from service

August 16th, 2013 |

The GOES-12 Sounder has sent its last data, ending more than 12 years of service. The GOES-12 Sounder was turned off at 1100 UTC on 13 August. GOES-12 was launched on July 23, 2001, and GOES-12 transmitted data from 16 August 2001 – 7 January 2002, and then more or less continuously from January 16, 2003 onward, a lengthy record of data collection for a geostationary satellite. GOES-12 initially served as GOES-East, replacing GOES-8. After April, 2010, when GOES-13 began service as GOES-East, GOES-12 was moved to 60 West longitude and supplied data over South America. The end of its fuel supply after a dozen years in orbit requires a decommissioning that is scheduled for Friday 16 August.

GOES-12 Sounder Imagery over South America, 0931 UTC on 13 August 2013

GOES-12 Sounder Imagery over South America, 0931 UTC on 13 August 2013

The last GOES Sounder images were centered over Bolivia, as shown above. Sounder data can be used to estimate Total Precipitable Water, or Cloud Top Pressure. A toggle between these last two products from GOES-12 is shown below.

GOES-12 DPI Total Precipitable Water and Cloud-Top Pressure, nominal time of 1100 UTC 13 August 2013

GOES-12 DPI Total Precipitable Water and Cloud-Top Pressure, nominal time of 1100 UTC 13 August 2013

The GOES-12 Imager was turned off at approximately 2330 UTC on 15 August 2013; De-orbit maneuvers are scheduled at 0100 and 1300 UTC on 16 August 2013.

The loss of data flowing from GOES-12 will have an impact on the GOES-13 scanning strategy. During routine GOES-13 scanning, there are six South American images every three hours. However, during past GOES-13 Rapid Scan Operations (RSO), only one South American Image was scanned every three hours — the Southern Hemisphere Short Sector (SHSS) that was south of the Equator, west of South America. (An example is here). In the scanning strategy now, a South American Image over the southern Amazon Basin (the South American ‘A’ Sector; here is a second example) will be produced near the top of the hour, and a South American Image over the southern part of the Continent (the South American ‘B’ Sector; here is a second example) will be produced near the bottom of the hour. An RSO call late on 13 August yielded the following two images in an hour.

GOES-13 South America Sectors (A and B)

GOES-13 South America Sectors (A and B)

=================UPDATE 16 August 2013=======================

GOES-12 10.7 µm infrared channel images (click image to play animation)

GOES-12 10.7 µm infrared channel images (click image to play animation)

The Imager was shut off around 2340 UTC on August 15 2013. The loop above shows the final two days of the Full Disk imagery. The final set of Imager imagery — all five channels — is below.

GOES-12 Imager over South America, 2328 UTC on 15 August 2013

GOES-12 Imager over South America, 2328 UTC on 15 August 2013

GOES-12 produced many excellent loops. Perhaps the most famous, a visible imagery loop of Hurricane Katrina in the Gulf of Mexico, is available here (Or here as a Quicktime movie).