Problem with NSIDC data

I was preparing files of daily data for the Climate Data Service when I received word that NSIDC (the National Snow and Ice Data Center) has suspended their sea ice extent reporting, due to a failure of one of the sensors on the satellite they use. They report thus:


NSIDC has suspended daily sea ice extent updates until further notice, due to issues with the satellite data used to produce these images. The vertically polarized 37 GHz channel (37V) of the Special Sensor Microwave Imager and Sounder (SSMIS) on the Defense Meteorological Satellite Program (DMSP) F-17 satellite that provides passive microwave brightness temperatures is providing spurious data. The 37V channel is one of the inputs to the sea ice retrieval algorithms, so this is resulting in erroneous estimates of sea ice concentration and extent. The problem was initially seen in data for April 5 and all data since then are unreliable, so we have chosen to remove all of April from NSIDC’s archive.

It is unknown at this time if or when the problem with F-17 can be fixed. In the event that the sensor has permanently failed, NSIDC is working to transition to either the DMSP F-18 or possibly the JAXA Advanced Microwave Scanning Radiometer 2 (AMSR2) on the Global Change Observation Mission – Water (GCOM-W) satellite. Transitioning to a different satellite will require a careful calibration against the F-17 data to ensure consistency over the long-term time series. While this transition is of high priority, NSIDC has no firm timeline on when it will be able to resume providing the sea ice time series. For background information on the challenges of using data in near-real-time, see the ASINA FAQ, “Do your data undergo quality control?”

I’ll be transmitting daily data which includes some of the erroneous time span soon (fortunately I captured their data just a few days ago), but with caveats noting the problem. More soon, including a look at the problem time span for both hemispheres.


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10 responses to “Problem with NSIDC data

  1. Countdown to WUWT conspiracy theory in 5…4…3…2…1…

    • There IS a conspiracy, actually. NASA should have received funding to place additional instrumentation long ago.

  2. Oh, Elon! If you’ve got a minute how about doing science a little favor?

  3. I have the data, faults and all, tabulated here and plotted here, with JAXA for comparison.

    • That page is a very fine piece of work Nick. Thank you – it looks like a non-trivial piece of work. And there is even a link to the sources: Tick V.G. :-)

      BTW the # bits of the link get lost in the redirects when I try to go there.

    • The first spike in the NSIDC SH data I recognized can be seen in Nicks plot as early as September 2015. So it is not a recent problem since April 2016.

  4. Martin Smith

    Lamont, you beat me to it. I was going to say: “Steven Goddard blog claiming fraud in 3…2…1…”

  5. If nothing else, it’s a nice example to show people who aren’t familiar with how satellite data are collected what kinds of issues can come up, and how that can affect results. I’m guessing the spurious data are *obviously* bad, but imagine if they weren’t; what sort of subtle errors could creep into the analysis?

  6. So, this is not about the records in question, but it is a spectacular almost unbelievable:
    http://thinkprogress.org/climate/2016/04/13/3768915/greenland-ice-melt-stuns/

    Blistering temperatures and rainfall over Greenland have jump-started the summer melt season weeks early. On Monday, a stunning 12 percent of Greenland’s massive ice sheet was melting — “smashing by a month the previous records of more than 10 percent of the ice sheet melting,” according to the Danish Meteorological Institute (DMI).

    DMI scientists were “at first incredulous.” One DMI climate scientist said, “We had to check that our models were still working properly.” But in fact, temperatures over parts of Greenland this month have been measured as high as 17.8°C — a scorching 64°F.

    “Even weather stations quite high up on the ice sheet observed very high temperatures on Monday,” explained Robert Fausto of the Geological Survey of Denmark and Greenland (GEUS). At one “site at 1840 meters [1.1 miles] above sea level, we observed a maximum temperature of 3.1°C [37.6°F]. This would be a warm day in July, never mind April.”

  7. Much more on the DMSP F-17 gremlins and the resulting cryodenialospheric brouhaha is available at:

    http://GreatWhiteCon.info/2016/04/satellite-problems-with-arctic-sea-ice-measurement/

    Lots of high resolution AMSR2 regional sea ice area plots are available too, if you scout around a bit. If this works, here’s one of them: