The DMSP satellite is still operating, but the SSM/I sensor is not
Regular readers will recall that on Feb 16th I blogged about this graph of arctic sea ice posted on the National Snow and Ice Data Center sea ice news page. The downward jump in the blue line was abrupt and puzzling.
Click for larger image
Today NSIDC announced they had discovered the reason why. The sensor on the Defense Meteorological Satellite Program (DMSP) satellite they use had degraded and now apparently failed to the point of being unusable. Compounding the bad news they discovered it had been in slow decline for almost two months, which caused a bias in the arctic sea ice data that underestimated the total sea ice by 500,000 square kilometers. This will likely affect the January NSIDC sea ice totals.
Figure 1. High-resolution image Daily Arctic sea ice extent map for February 15, 2009, showed areas of open water which should have appeared as sea ice. Sea Ice Index data. About the data. Please note that our daily sea ice images, derived from microwave measurements, may show spurious pixels in areas where sea ice may not be present. These artifacts are generally caused by coastline effects, or less commonly by severe weather. Scientists use masks to minimize the number of “noise” pixels, based on long-term extent patterns. Noise is largely eliminated in the process of generating monthly averages, our standard measurement for analyzing interannual trends. Data derived from Sea Ice Index data set.
Figure 2.
High-resolution imageDaily total Arctic sea ice extent between 1 December 2008 and 12 February 2009 for Special Sensor Microwave/Imager SSM/I compared to the similar NASA Earth Observing System Advanced Microwave Scanning Radiometer (EOS AMSR-E) sensor. —Credit: National Snow and Ice Data Center
Dr. Walt Meier of NSIDC had planned to do a guest post here on WUWT, but this evening, with the magnitude of the problem looming, he’s asked to defer that post until later. I certainly can’t fault him for that. He’s got his hands full. Hopefully they have a contingency plan in place for loss of the sensor/space platform. I applaud NSIDC for recognizing the problem and posting a complete and detailed summary today. I’ve resposted it below in its entirety. Note that this won’t affect other ice monitoring programs that use the Advanced Microwave Scanning Radiometer (EOS AMSR-E) sensor, which is on an entirely different platform, the AQUA satellite.
UPDATE: 2/19 Walt Meier writes with a clarification: “One detail, though perhaps an important [one]. I realize that it is bit confusing, but it is just one channel of the sensor that has issues. And it isn’t so much that it “failed”, but that quality degraded to the point the sea ice algorithm – the process to convert the raw data into sea ice concentration/extent – failed on Monday.” – Anthony
From NSIDC Sea Ice News:
As some of our readers have already noticed, there was a significant problem with the daily sea ice data images on February 16. The problem arose from a malfunction of the satellite sensor we use for our daily sea ice products. Upon further investigation, we discovered that starting around early January, an error known as sensor drift caused a slowly growing underestimation of Arctic sea ice extent. The underestimation reached approximately 500,000 square kilometers (193,000 square miles) by mid-February. Sensor drift, although infrequent, does occasionally occur and it is one of the things that we account for during quality control measures prior to archiving the data. See below for more details.
We have removed the most recent data and are investigating alternative data sources that will provide correct results. It is not clear when we will have data back online, but we are working to resolve the issue as quickly as possible.
Where does NSIDC get its data?
NSIDC gets sea ice information by applying algorithms to data from a series of Special Sensor Microwave/Imager (SSM/I) sensors on Defense Meteorological Satellite Program (DMSP) satellites. These satellites are operated by the U.S. Department of Defense. Their primary mission is support of U.S. military operations; the data weren’t originally intended for general science use.
The daily updates in Arctic Sea Ice News & Analysis rely on rapid acquisition and processing of the SSM/I data. Because the acquisition and processing are done in near-real time, we publish the daily data essentially as is. The data are then archived and later subjected to very strict quality control. We perform quality control measures in coordination with scientists at the NASA Goddard Space Flight Center, which can take up to a year. High-quality archives from SSM/I, combined with data from the earlier Scanning Multi-channel Microwave Radiometer (SMMR) data stream (1979–1987) provide a consistent record of sea ice conditions now spanning 30 years.
Data error sources
As discussed above, near-real-time products do not undergo the same level of quality control as the final archived products, which are used in scientific research published in peer-reviewed journals. However, the SSM/I sensors have proven themselves to be generally quite stable. Thus, it is reasonable to use the near-real-time products for displaying evolving ice conditions, with the caveat that errors may nevertheless occur. Sometimes errors are dramatic and obvious. Other errors, such as the recent sensor drift, may be subtler and not immediately apparent. We caution users of the near-real-time products that any conclusions from such data must be preliminary. We believe that the potential problems are outweighed by the scientific value of providing timely assessments of current Arctic sea ice conditions, as long as they are presented with appropriate caveats, which we try to do.
For several years, we used the SSM/I sensor on the DMSP F13 satellite. Last year, F13 started showing large amounts of missing data. The sensor was almost 13 years old, and no longer provided complete daily data to allow us to track total daily sea ice extent. As a result, we switched to the DMSP F15 sensor for our near-real-time analysis. For more information on the switch, see “Note on satellite update and intercalibration,” in our June 3, 2008 post.
On February 16, 2009, as emails came in from puzzled readers, it became clear that there was a significant problem—sea-ice-covered regions were showing up as open ocean. The problem stemmed from a failure of the sea ice algorithm caused by degradation of one of the DMSP F15 sensor channels. Upon further investigation, we found that data quality had begun to degrade over the month preceding the catastrophic failure. As a result, our processes underestimated total sea ice extent for the affected period. Based on comparisons with sea ice extent derived from the NASA Earth Observing System Advanced Microwave Scanning Radiometer (EOS AMSR-E) sensor, this underestimation grew from a negligible amount in early January to about 500,000 square kilometers (193,000 square miles) by mid-February (Figure 2). While dramatic, the underestimated values were not outside of expected variability until Monday, February 16. Although we believe that data prior to early January are reliable, we will conduct a full quality check in the coming days.
Sensor drift is a perfect but unfortunate example of the problems encountered in near-real-time analysis. We stress, however, that this error in no way changes the scientific conclusions about the long-term decline of Arctic sea ice, which is based on the the consistent, quality-controlled data archive discussed above.
We are actively investigating how to address the problem. Since we are not receiving good DMSP SSM/I data at the present time, we have temporarily discontinued daily updates. We will restart the data stream as soon as possible.
Some people might ask why we don’t simply switch to the EOS AMSR-E sensor. AMSR-E is a newer and more accurate passive microwave sensor. However, we do not use AMSR-E data in our analysis because it is not consistent with our historical data. Thus, while AMSR-E gives us greater accuracy and more confidence on current sea ice conditions, it actually provides less accuracy on the long-term changes over the past thirty years. There is a balance between being as accurate as possible at any given moment and being as consistent as possible through long time periods. Our main scientific focus is on the long-term changes in Arctic sea ice. With that in mind, we have chosen to continue using the SSM/I sensor, which provides the longest record of Arctic sea ice extent.
For more information on the NSIDC sea ice data, see the following resources on the NSIDC Web site:
- Sea Ice Index
- Why is the Sea Ice Index product used to study sea ice?
- Do your data undergo quality control?
There has been and are significant problems with the F15 satellite.
http://www.ssmi.com/ssmi/ssmi_browse.html
“Since 2006-Aug-14 UTC, SSM/I F15 22GHz(V) channel has been degraded by a RADCAL beacon. The interference has been characterized and removed; ocean products are now available.”
“SSM/I F15 from August 14, 2006 to the present should not be used for climate work.”
“Beacon Alert!!!
The F15 beacon problem has gotten much worse, beginning January 15, 2009.
Until further notice, do not use recent SSM/I F15 for research.”
http://nsidc.org/data/docs/daac/f15_platform.gd.html
“Also carried on board DMSP F15 is an experimental payload, called the Radar Calibration (RADCAL) beacon, that is used to transmit C-band data for the purpose of testing C-band tracking radar performance at Vandenberg Air Force Base. RADCAL also transmits Doppler data for the Naval Research Laboratory’s Coherent Electromagnetic Tomography (CERTO) experiment.
The RADCAL beacon operates at 150 MHz and 400 MHz. On-orbit testing conducted in August 2005 confirmed that transmissions from the RADCAL 150 Mhz beacon produced interference in the SSM/I 22 GHz vertical polarization (22V) channel and that the 400 Mhz beacon interfered with SSMT-2 channel 4 performance. The SSMT-2 on F15 has since been declared non-operational due to an unrelated component failure. Thus, users of F15 SSM/I data should be advised that the 22V channel will be dramatically degraded during RADCAL beacon transmission, particularly with regards to snow classification and depth.”
Oh yes the bears.
I just saw, again, the World Wildlife Fund (WWFusa.com commercial on MSNBC using the polar bears and AGW to pitch for donations.
“The ice is all vanishing the ploar bears are being stranded, mother bears are leaving their cubs, they’re dying and need saving, please donate ,,,,,”
All very sad. Not the bears, they’re fine.
It’s the the pathetic commercial and those behind it that is sad.
It’s such a shamelsss display of blatant lying.
Extending my last post to show that the current problem is in the 22v channel,
http://nsidc.org/data/docs/daac/nsidc0080_ssmi_nrt_tbs.gd.html
“On 16 February 2009, NSIDC noticed significant problems with the NRT brightness temperature product. Upon investigation, the problem was found to be due to an issue with the DMSP F15 SSM/I 22 GHz frequency brightness temperature fields. The problem began around 1 January 2009 and gradually worsened until it became noticeable in the sea ice product (NRT DMSP SSM/I Daily Polar Gridded Sea Ice Concentrations). NSIDC is working to correct the issue and provide reliable NRT brightness temperature data. In the meantime, F15 data since 1 January 2009 should not be used.”
and
“As of 02 June 2008, NSIDC has switched its SSM/I processing stream from the DMSP-F13 satellite to the DMSP-F15 satellite. This is due to a failing recorder on F13 which has been operational since 1995 and is expected to be decommissioned in the near future. For data continuity, F15 data has been acquired back to 01 January 2008. F13 products since 01 January 2008 remain and will continue to be produced until data quality degrades to an unusable level or the satellite is out of service.
You may continue to use data from F13 or switch to the data from F15. In switching, you should be aware of the following differences in the satellite data:
Interference with the F15 22 GHz channel from a radar calibration (RADCAL) beacon biasing the F15 brightness temperatures 10 K to 15 K higher than F13.”
Just ask the residents of the Seward Peninsula and Pt. Barrow, Alaska if they no longer have to beat the Polar Bears off with shotguns. As for the rest of the uninhabited North, who’s there to know if the Polar Bears are going extinct?
Ask the Inuit, Eskimos and other tribes.
When in doubt, check with the locals.
So they want your money? That says volumes about the status of the Polar Bear decline. What will they do with your money? Raise Polar Bears?
There’s a reason why affected Alaskan residents have to fight off the Polar Bears. They stalk and eat anything, including residents. They are always aggressive and have no fear of man.
So, who wants to raise these things?
Yeh, but the ER doctor guy is really cute. And if he is shameless to boot, count me a warmer. Gettin warm already.
I’m wondering how long it will be before the new Washington administration finds a way to shut this and other divisive sites down in the interests of Unity.
REPLY: I’m already working on it. I’m getting an offshore co-lo site in Tuvalu. – Anthony
😉
From Cryosphere Today,
We do not know where George Will is getting his information, but our data shows that on February 15, 1979, global sea ice area was 16.79 million sq. km and on February 15, 2009, global sea ice area was 15.45 million sq. km. Therefore, global sea ice levels are 1.34 million sq. km less in February 2009 than in February 1979. This decrease in sea ice area is roughly equal to the area of Texas, California, and Oklahoma combined.
It is disturbing that the Washington Post would publish such information without first checking the facts.
Cryosphere Today’s own graph clearly shows the global sea ice anomaly at the end of 1979 at the same level as the start of 2009.
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily.ice.area.withtrend.jpg
And the outrageous piece of cherry picking of one date, February 15 to ‘prove’ the opposite is one of the lamest things I’ve seen in the climate debate, which is saying a lot.
One wonders why they don’t feel shame or embarassment at such blatant distortions of the facts.
Appears that someone may still be processing data from the F15 SSM/I:
http://iabp.apl.washington.edu/maps_daily_ncepice.html
Second that!
*****************************
Looking forward to Dr. Meier’s guest post.
From Cryosphere Today,
“and on February 15, 2009, global sea ice area was 15.45 million sq. km.”
Now that’s really something.
What are they doing using the the “data dropouts and bad data due to satellite issues” from NSIDC?
Probably a dumb OT question: If the satellite is in a Polar Orbit, why then do the images still have a hole at the pole(s)?
http://www.guardian.co.uk/environment/2003/dec/11/weather.climatechange
Paul Brown in Milan guardian.co.uk, Thursday 11 December 2003 02.12 GMT Article historyThe Inuit people of Canada and Alaska are launching a human rights case against the Bush administration claiming they face extinction because of global warming.
By repudiating the Kyoto protocol and refusing to cut US carbon dioxide emissions, which make up 25% of the world’s total, Washington is violating their human rights, the Inuit claim.
For their campaign they are inviting the Washington-based Inter-American Commission on Human Rights to visit the Arctic circle to see the devastation being caused by global warming.
Sheila Watt-Cloutier, the chairwoman of the Inuit Circumpolar Conference, which represents all 155,000 of her people inside the Arctic circle, said: “We want to show that we are not powerless victims. These are drastic times for our people and require drastic measures.”
The human rights case was announced at the climate talks in Milan, Italy, where 140 countries are trying to put the finishing touches to the Kyoto protocol, the first international agreement to reduce greenhouse gases. The backing of Russia, which is hesitating about ratifying the agreement, is required to bring the protocol into force. The US is trying to persuade the Russian president, Vladimir Putin, not to sign the protocol.
The Inuit have no voice at the conference, since they are not a nation state, but Mrs Watt-Cloutier said: “We are already bearing the brunt of climate change – without our snow and ice our way of life goes. We have lived in harmony with our surroundings for millennia, but that is being taken away from us.
“People worry about the polar bear becoming extinct by 2070 because there will be no ice from which they can hunt seals, but the Inuit face extinction for the same reason and at the same time.
http://news.nationalgeographic.com/news/2000/12/122900inuits.html
Global Warming Melts Inuit’s Arctic Lifestyle
Lisa Krause (July 12, 2000)
Traditionally, the 130 members of the Inuit community of Sachs Harbor, located on the western tip of Banks Island in the Canadian Arctic, supported themselves through age-old patterns of hunting, trapping, and fishing. Recently, however, members of the community have taken on a new role: climate-change observers.
Here, 400 miles (640 kilometers) north of the Arctic Circle, global warming is not a theory that is debated among scientists, but a reality of everyday life. Sea ice is thinning, and disappearing. Indigenous animals are moving farther north. And melting permafrost has loosened the ground enough to weaken foundations and cause homes to lean. This, plus rising sea levels, threatens to displace an entire community.
Surrounded by signs of change, in 1998 the residents of Sachs Harbor devised a plan to document the changes affecting their home and bring attention to the very obvious signs of global warming.
Led by Rosemarie Kupatana, a Sachs Harbor resident, Inuit Observations on Climate Change is a community-based project developed in cooperation with the International Institute for Sustainable Development. Aided by project scientists, community members are working to produce a video that will record the changes threatening their home.
SIGNS OF CHANGE CLOSE TO HOME
Among the most alarming changes is the disappearance of native species. Caribou, long a staple of Inuit diet, are falling through once-solid sea ice. Polar bears are moving farther north, as are seals, who need the shelter of pack ice to give birth to their young.
As traditional Arctic species move north, new species are moving in. Grizzly bears have been spotted in territory once dominated by polar bears. Salmon, never before caught this far north, are making appearances in fishermen’s nets.
How do you get sea levels to rise dramatically in the Arctic, but here they have only risen 2″ in the last century?
Why would there be a problem with Polar Bears moving farther north when the Inuit can load up on Salmon that have moved in behind them?
Makes me wonder how long the Inuit have been around if during some of the past warming periods they saw the Caribou fall through the ice in the past?
(seems like a daily dinner bonus…hey honey….it’s caribou stew tonight !!)
Beat off polar bears with shotguns? A shotgun is likely to only irk a polar bear. A .50 cal Barrett semi auto rifle is more like it.
By the way,
Once again a huge ‘thank you’ to WUWT, and all of the other skeptics who endure the ad homs, the disparaging, the slander and vilification of the AGW promotion industry for showing yet another example of how a major tenet of AGW is flat out wrong.
thefordprefect,
I frankly wonder if there is any truth at all in the article you posted.
Mannnn… the polar bears aren’t killing us anymore and now we have lots of fish… also the caribou are still hanging around. Actually, Sachs Harbour is part of Canada. Canada can no longer care for her own? Perhaps socialism was not a good choice for Canada.
Mike Borgelt (05:04:44) :
No, a shotgun slug would do the trick very well actually – just remember to not have bird shot anywhere near your ammo bag.
There are similarly shaped areas of “missing” ice in the Antarctic pictures as well. Please see:
http://nsidc.org/data/seaice_index/images/daily_images/S_daily_extent_hires.png
The “upper left” ice field has an angular section of ice “missing” and the “left” ice field has a similar hard edge on the “top” that might be “missing” ice. Perhaps WattsUpWithThat can contact Dr. Meier and ask him to take a closer look at the Antarctic data (that seems to be taking a simlarly unusual loss in ice) as well?
Last post should stipulate the image dated 18 February 2009.
Philip_B (22:16:55) :
hunter (05:37:54) :
thefordprefect,
I frankly wonder if there is any truth at all in the article you posted.
Prove to me the statements made are false. They were 2 articles from 2 sources that were not blogs.
bluegrue,
The pooint is that
1) the data source is no longer credible
2) if it is correct, the actual difference is not significant, and is not indicative of anything like what Hansen & co. claim- that we are near a tipping point with a catastrophic end result.
JUST ASKING….
Looking back at the figure showing the apparently enormous [and subsequently discovered to be erroneous] drop in sea ice, we se the magnitude of the drop is from about 14.5 to 13.8, or 0.7. (0.7/14.8)*100= 4.7%
Am I missing something here, or would the addition of error bars obliterate all or most of any apparent differences between yearly averages (assuming the data isn’t corrupted to begin with)?