Drift

The Rabett made an interesting post recently, based on an idea that occurred to him on the subject of the “Cruz pause” (a drawback to slumming at Lucia’s).


If the changes in temperature over short periods (like days or months or even annually) track each other, even just in direction in the satellite and surface records (so) then that is pretty convincing evidence that the problem is a long term drift in one or the other and that on the short term they are measuring the same thing.


Eli’s approach was to compare the land-only part of RSS to the surface temperature data from CRUTEM4, from 2005 through 2015. It occured to me to compare things that are supposed to be measuring the same thing (at least approximately), the lower-troposphere temperature from RSS and UAH, and the lower-troposphere temperature from RATPAC (for the 850-300 hPa level).

As for data from “Wood for Trees,” despite its value (which is considerable), we don’t need no stinkin’ Wood for Trees. Nor do we need to restrict ourselves to post-2005 data, I went for the entire period covered by the satellites. I did, however, average the satellite data over 3-month periods to emulate the RATPAC data. Then I removed the “trend” part (the long-term stuff) from each with a lowess smooth. This enables us to compare the “ups and downs” by comparing what’s left over (a.k.a. residuals). Namely, this:

detrend

Just from the satellite-vs-surface comparison, Eli finds that “MSU and CRUTEM4 are consistent on a monthly and even an annual basis.” But for the short-term stuff as shown here, MSU and RATPAC are beyond consistent — they’re stunningly similar. Yes, they’re measuring the same thing, at least (very very) approximately. No doubt about it.

But that doesn’t tell us whether they’re drifting apart. For that we should compare the longer-term stuff, the smooths. Like here:

trend

Yes, they’re drifting apart. No doubt about it either.

This uses UAH v5.6, but Spencer and Christie are trying to switch to their v6, which is a lot closer to the RSS result. Their reasons are unclear — but the suspicious among us might think it’s because it’s a lot closer to the RSS result.

But the upshot is that there is drift — the instrumentation issue, most likely with the satellite data, isn’t a short-term fluctuation thing, it’s a long-term drift thing. As per the chief bunny, I’ll also point you to Nick Stokes.

As for the “Cruz pause,” it’s about as believable as the “Monckton pause.” Interested bunnies can decide for themselves which of the two should feel more insulted by the comparison.


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13 responses to “Drift

  1. Masking only for co-located observations prior to averaging would help further to illustrate the point as it would remove the criticism that Ratpac is not adequately ‘global’

  2. Say guys, want to write a paper?

    FWIW Eli used only used 2005 to 2015 to spread out the figure during the period of the divergence and emphasize the short term agreement

  3. So… the AGW denier meme “the satellite data is the most accurate” turns out to be “the satellite data most accurately reflects our legendary confirmation bias”. Who knew? :-)

  4. Very nice. Ugh, the Engineers are denying it up again today on the Faculty email list. One of the specimens is a so called expert in time series data. Awful, embarrassing, depressing.

  5. Lets extend the period to 18 years, and stay above the surface in the free troposphere: http://postmyimage.com/img2/397_Tropospheretrends.png
    There are other radiosonde datasets as well, but they stop in 2012. However, their somewhat shorter trends would also fall between the red and yellow trendlines in the chart, way above the cool blue ones, that the deniers cherry-pick and like..

  6. Just checking if comment works- just had one disappear (didn’t get the usual “your comment is awaiting moderation”)

  7. Remember Pinko, it’s the surge! the surge!

  8. Weng et al (http://link.springer.com/article/10.1007%2Fs00382-013-1958-7) reported that lowest AMSU channel were significantly impacted by cloud liquid water, with higher rates of warming when cloud effects were ‘removed’ (or at least when only “clear-sky” data were used). Could the ‘drift’ in satellite temps be related to this cloud contamination, given that water vapour is apparently increasing in the lower atmosphere (https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-4-2-1.html)?

  9. Would it not be interesting to see what Po-Chedley’s work on the MSU correction gives? If this is a problem with the satellite or the MSU it should show up there as well. If not it is a methodological issue with S&C – but I’m inclined to assume innocence where they are concerned.

  10. The difference between 5.6 and 6 has to do with the fact that UAH USED to do this — “UAH does not yet correct the diurnal drift for satellites carrying Advanced Microwave Sounding Units because they attempt to use these satellites during periods when the diurnal drift is small.”

    http://www.theguardian.com/environment/climate-consensus-97-per-cent/2015/mar/25/one-satellite-data-set-is-underestimating-global-warming

    Now they are using a diurnal drift correction – but this got them closer to the RSS than to the CRUtemp…

    So there is something affecting the diurnal drift, if eliminating it effectively gets rid of the problem.

    Yeah… you folks can do this.

  11. One day I would like Eli to adopt me. And for Tamino to be my foster brother. ;-)

    As for the proponents of “satellites disprove global warming” meme – ruh roh…

  12. I’m vying to be a pet in that household, Bernard.
    When Robert Way writes
    “Masking only for co-located observations”

    Can someone expand that for the woof side of comprehension? I’m hoping it means “satellite and balloon/sonde observations located at the same time/place”

    (I have mentioned my uninformed suspicions about that dark gray cloud you can see moving around over and downwind of India (and sometimes clearly fenced in by the Himalayas) in all the DSCOVR imagery).

    Someone please tell me it’s covered so I can quit asking whether the increase in smog thereabouts could have begun confusing the satellites in the past 10-15 years.