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Thursday, March 3, 2016

The mid-troposphere has been warming faster than you thought

Sou | 3:12 AM Go to the first of 45 comments. Add a comment

A new version of the RSS dataset has been announced in a paper in the AMS Journal of Climate. The paper, by Carl Mears and Frank J. Wentz, was published before the new version has appeared. This is in contrast to UAH, where the paper hasn't yet appeared but version 6.0 beta came out in April last year, and is now at beta 5.

The paper is about middle troposphere measurements, not lower troposphere which is what is usually discussed here. However, it's about the same instruments that are used to estimate lower troposphere temperatures: Microwave Sounding Unit (MSU) channel 2, and the Advanced Microwave Sounding Unit (AMSU) channel 5.

In the abstract, the authors say (my paras):

Previous versions of the RSS dataset have used a diurnal climatology derived from general circulation model output to remove the effects of drifting local measurement time. In this paper, we present evidence that this previous method is not sufficiently accurate, and present several alternative methods to optimize these adjustments using information from the satellite measurements themselves. These are used to construct a number of candidate climate data records using measurements from 15 MSU and AMSU satellites.

The new methods result in improved agreement between measurements made by different satellites at the same time. We choose a method based on an optimized second harmonic adjustment to produce a new version of the RSS dataset, Version 4.0.

The new dataset shows substantially increased global-scale warming relative to the previous version of the dataset, particularly after 1998. The new dataset shows more warming than most other middle tropospheric data records constructed from the same set of satellites. We also show that the new dataset is consistent with long-term changes in total column water vapor over the tropical oceans, lending support to its long-term accuracy.



The authors mention the Po-Chedley paper on diurnal cycle contamination, and talked about how they went about improving the data, correcting for this. They also discussed how they tested their methods, which seems to have been quite thorough. The authors explain:
The derivation of long-51 term trends in tropospheric temperature from satellite observations requires that the diurnally varying component for the observation be removed. This is because the local observation time for most of the satellites drifts over time (Christy et al. 2000; Mears and Wentz 2005), causing diurnal variations to be aliased into the long-term record. Ideally, we would like to use a highly accurate, independent source of atmospheric and surface temperature specify the diurnal cycle. Unfortunately, no such data are available.
They discussed three different approaches for removing the effects of the diurnal cycle, and explained why they adopted the one they did.

[Amended] Below are some charts of the mid-troposphere temperature record, using the two versions of RSS, and both versions of UAH - v5.6 and v6.0 beta 5. The chart is all years to 2014 2015. It stops at 2014 because that's as far as the comparison goes in the paper (which was probably written before the end of 2015):

Data sources: RSS v3.3 and v4; UAH v5.6 and 6.0 beta 5

In the above chart, the trend from 1979 to 2014 is a bit different to what the paper shows, so I might have the data wrong or there may have been further adjustments since the paper was written, or there's some other explanation. I adjusted the RSS baseline to match that of UAH (1981-2010). I got the v4 data from here

The data for RSS v4 has been changed/corrected with a new source here and here. Change the "channel" drop down box here to see the TMT v4 version, and click "download data" for the data. The previous source is no longer available (thanks Anonymous in the comments). The new source is now consistent with the paper, so I've updated the chart. The data also now goes through to the present, so in the above chart the trends are now to 2015 and are:
  • UAH v5.6 0.06 C/decade
  • UAH v6.0 beta 5 0.072 C/decade
  • RSS v3.3 0.08 C/decade
  • RSS v4 0.13 C/decade
Updated by Sou 5:00 pm AEDT 4 March 2016

From the paper, the trend goes from 0.078 C/decade with v3.3 to 0.125 C/decade in v4.0 after all adjustments. Below is the relevant chart from the paper (click to enlarge as always):


This will make UAH odd one out again, as far as mid-troposphere temperatures go. It looks as if the changes are around the time that many of us noticed in the lower troposphere (early 2000s), though the paper doesn't discuss the impact there. Since the same instruments are used, I expect there will be a difference. From the RSS website, where TLT is the lower troposphere:
TLT is a more complex data set constructed by calculating a weighted difference between measurements made at different Earth incidence angles to extrapolate MSU channel 2 and AMSU channel 5 measurements lower in the atmosphere.
I don't know when the new version will be out, however they do provide a preview website.


References and further reading


Carl A. Mears and Frank J. Wentz, 2016: "Sensitivity of satellite-derived tropospheric temperature trends to the diurnal cycle adjustment." J. Climate doi: http://dx.doi.org/10.1175/JCLI-D-15-0744.1 (subs req'd)

Stephen Po-Chedley, Tyler J. Thorsen, and Qiang Fu, 2015: "Removing Diurnal Cycle Contamination in Satellite-Derived Tropospheric Temperatures: Understanding Tropical Tropospheric Trend Discrepancies." J. Climate, 28, 2274–2290. doi:http://dx.doi.org/10.1175/JCLI-D-13-00767.1 (pdf here h/t E Swanson)

New Dataset from RSS: End of the Satellite “Pause”? - article by Tamino

45 comments :

  1. So it looks like RSS will no longer be in favor with the denialist camp ...

    ReplyDelete
    Replies
    1. Yep, I've been spreading the good news on WUWT and Spencer's.

      Delete
    2. This comment has been removed by the author.

      Delete
    3. He has a protest article up -- calling it the "Karlization" of the record.

      Delete
    4. http://davidappell.blogspot.dk/2016/02/those-arbitrary-changes-to-uahs-model.html
      “We therefore changed the AMSU5 reference Earth incidence angle (from 35.0 to 38.3 deg.) so that the trends over Greenland and the Himalayas were in much better agreement with the surrounding areas.”

      Delete
  2. Po-Chedley et al. (2015) is available HERE. They compare four time series, UAH, RSS, NOAA and their UW, with the result that UAH is the "odd man out". Of course, the UAH version they use is the earlier 5.6 time series and the latest version 6 presents even lower trend results. US Rep. Lamar Smith and Sen. Ted Cruz will need to "re-calibrate" their anti-science rants...

    ReplyDelete
    Replies
    1. How do you re-calibrate "over my dead body"?

      Delete
    2. I suppose you could add or substitute "bleeding" and/or "still-warm."

      Delete
    3. I suppose you could add or substitute "bleeding" and/or "still-warm."

      Delete
  3. What a sad day for climate science. Now UAH version uno (I'll link to the code as soon as I locate it) is the only purely raw, - published far ahead of its release - and completely unadulterated data available.

    ReplyDelete
    Replies
    1. Irony does not work on the internet.

      Delete
    2. Especially when your screen name is misspelled.

      Best,

      D

      Delete
    3. Well there you go. I didn't know there was such a thing as raw satellite temperature data. Do these things have a means of directly measuring temperature after all?

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    4. Millicent, no, they don't. :)

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    5. A thermomenter hanging on a long rope from a satellite would be rather warm as a result of the atmospheric friction...

      ;-)

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    6. ...thermometer...

      ALthough a febrile mental condition is probably what will result from all this...

      Delete
    7. Bernard - at Climate Etc., I once posted they could ground truth the satellites by hanging thermometers off them on long ropes. Great minds stink alike.

      Delete
    8. A thermomenter hanging on a long rope from a satellite would be rather warm as a result of the atmospheric friction...

      Not if the satellite is in geosynchronous orbit. You'd just need a really, really long rope.

      Delete
    9. "A thermometer hanging on a long rope from a satellite would be rather warm as a result of the atmospheric friction"

      Careful now: frictional heating from satellite thermometer tethers could be the new Russian steam pipes.

      Delete
    10. Of course there's no such thing as a satellite temperature measurement.

      Temperatures are all calculated based on various microwave radiance readings at different times, angles and frequencies, merged from different satellites using merging parameters, and then weighted based on a model of the atmosphere.

      I don't think "raw" data would be much help to anyone.

      Delete
  4. That didn't take long - Anthony Watts calls this "The ‘Karlization’ of global temperature".

    ReplyDelete
    Replies
    1. Mears had better get his email stream ready for Lamar Smith

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    2. The Wattsification of Climate Denial continues.

      RSS is now part of the Vast Global Conspiracy.

      Wasttsification eats brains and makes pepl stoopid.

      Delete
    3. Anthony Watts - who'd be him? He's stuck in a nightmare world where he and his ever-dwindling band of co-loons are the ever-dwindling non-odd-toed-ungulates in Ionesco's Rhinoceros.

      And it's a misery richly deserved!

      Delete
    4. It's called self-marginalisation

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    5. Smith's going to have fun FOIA'ing Mears. He can't :-)

      Delete
    6. 'Karlization' means to make oneself a primary target of malicious and vindictive climate denying politicians and bloggers.

      Delete
    7. Anthony Watts calls this "The ‘Karlization’ of global temperature".

      Oh FFS. Malignant clown.

      Delete
    8. It's not "science" if you adjust any data upwards don't you know. it only counts if you go down.

      Delete
    9. "it only counts if you go down."

      Bang on. Doctor Roy adjusted his temperatures in the WUWT approved direction and they loved him fort it even though he neglected to show anybody his workings.

      Delete
    10. D.C.Petterson, I see you've had a comment deleted on WUWT because you used the D word. Presumably you weren't talking about satellite or pause deniers.

      Delete
    11. The main lesson for me from all this is that Watts now accepts that satellite data can be easily manipulated and should not be trusted - whereas before he was saying it was desperation for anyone to diss the satellite data.

      Delete
    12. Roy Spencer is now also part of the "Karlization’ of global temperature": “I’ve always cautioned fellow skeptics that it’s dangerous to claim no warming”

      Always.

      Delete
    13. Below is an actual exchange on Spencer's own blog:

      Larry Fig
      March 1, 2016 at 11:34 AM
      Dr. Spencer,

      Might I kindly suggest you take another look at your new way of adjusting satellite data to get temperatures? Obviously your Mar. data is too high.

      With respect,
      Larry

      Roy W. Spencer, Ph. D.
      March 1, 2016 at 11:45 AM
      let me know what you think the answer should be and I’ll correct it. LOL

      Larry Fig says:
      March 1, 2016 at 11:54 AM
      As long as you don’t make it higher than the peak in 1998 we can say that the the pause continues. What you are doing is very dangerous and irresponsible.

      With respect,
      Larry

      http://www.drroyspencer.com/2016/03/uah-v6-global-temperature-update-for-feb-2016-0-83-deg-c-new-record/#comments

      Delete
  5. The new dataset is now included here:
    http://images.remss.com/msu/msu_data_monthly.html?type=trend

    not in the link that you provided (anymore?)

    ReplyDelete
    Replies
    1. "Anonymous", your link opens up with "Channel: TLT", but that is not the v4.0 result (it's the old v3.3 result). But the drop-down list for "Channel" does have v4.0 results for TTT and TMT.

      TLT for v4.0 is likely to follow, but I have not seen any projected release date yet.
      --GP Alldredge

      Delete
  6. Spencer will be ecstatic. Now UAH 6 will be the standard most accurate data set.

    ReplyDelete
  7. Has anyone else noticed that Watty has ads playing sound on WU now?

    Feeling the pinch?

    ReplyDelete
  8. Thanks to Anonymous, I've been able to update the TMT chart with the correct data, which is now consistent with the paper. I've amended the article accordingly.

    ReplyDelete
  9. Senior seems or appears to be upset about this new peer reviewed paper. Suggests that the always error prone Spencer and Christy should have been peer reviewers on JoC version of paper.

    https://twitter.com/RogerAPielkeSr/status/705160376300675072
    https://twitter.com/RogerAPielkeSr

    Ho hum.

    It looks like Spencer and Christy will be the only proxy based time series index meeting the "fixed" nature of a "gold standard" of "flatlined" data acceptable to their fellow peers, like Curry, like Senior, like Watts, like Godtard, like Monkers, like Cruz and especially like Lamar Smith.

    ReplyDelete
    Replies
    1. Spencer and Christy deviating from what everyone else is seeing. We know how that ends.

      Delete
    2. The whole discussion is, once again, illuminating when it comes to Roger Pielke Sr.

      Apparently Spencer & Christy are "affected" by this paper...

      Delete
    3. Related to Senior but not limited to him, one of the things I’ve been amazed at lately is how science has progressed over the last couple decades while some individuals haven’t. To illustrate, Senior and a graduate student published a paper in 2005 containing photographs showing poorly sited stations. Their conclusion: It is “not advisable to use” data from these stations. A few weeks later while paddling a kayak in northern Wisconsin on a camping trip, I suddenly realized that Senior never actually looked at the data. So I did, wrote a paper, and submitted it. I didn’t rebut anything Senior wrote, I just used the metadata they had generated. But my goodness what response: Senior argued that my paper should only be accepted for publication if he could publish a rebuttal in the same issue. The editor said no, as my paper didn’t impugn his work at all. I was told he then took the matter to the editior-in-chief and got the same response and then on to the AMS publications commission, which again gave the same response. In the intervening years he doesn’t seem to have changed his view of how he and his colleagues should use peer review. Ah, ‘tis nice to be retired and feeling freer to share these experiences publically. FYI, my paper is available here: http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-87-8-1073.

      Delete
    4. Thanks Thomas. I can understand why Senior tried to interfere with the publication of your paper.

      "This analysis takes the opportunity afforded by the work
      of Davey and Pielke to evaluate not only the effects of poor station siting, but also the homogeneity adjustment techniques painstakingly developed over many years at the National Climatic Data Center. The results indicate that the work was not done in vain: the homogeneity adjustments did an excellent job of accounting for time-dependent biases at the stations examined and the homogeneity-adjusted data do not indicate any time-dependent bias caused by current poor station siting"

      And I am guessing that your colleagues were following that example when they took the same approach to rebutting Anthony Watts' claims a few years later.

      http://thinkprogress.org/climate/2010/01/28/205416/watts-not-to-love-new-study-finds-the-poor-u-s-weather-stations-tend-to-have-a-slight-cool-bias-not-a-warm-one/

      Delete
    5. Thanks for that background, Tom. I wondered whether Pielke Sr demanded(*) one of you guys review the Fall et al paper.

      * because surely he would *demand* that, considering his own views that those who are 'affected' by a paper should be allowed to review the paper!

      Delete

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