Tropospheric hot spot?

I think I might just briefly mention the recent Sherwood & Nishant paper, Atmospheric changes through 2012 as shown by iteratively homogenized radiosonde temperature and wind data, which appears to show what some have called a tropospheric hot spot. It’s also been covered elsewhere. As the abstract of the paper says (my bolds)

Temperature trends in the updated data show three noteworthy features. First, tropical warming is equally strong over both the 1959–2012 and 1979–2012 periods, increasing smoothly and almost moist-adiabatically from the surface (where it is roughly 0.14 K/decade) to 300 hPa (where it is about 0.25 K/decade over both periods), a pattern very close to that in climate model predictions. This contradicts suggestions that atmospheric warming has slowed in recent decades or that it has not kept up with that at the surface. Second, as shown in previous studies, tropospheric warming does not reach quite as high in the tropics and subtropics as predicted in typical models. Third, cooling has slackened in the stratosphere such that linear trends since 1979 are about half as strong as reported earlier for shorter periods.

As I understand this, it is indicating the the rate of warming in the troposphere exceeds that at the surface. This is essentially because water vapour does not condense (and release latent heat) equally at all altitudes. It tends to do so more in the at altitudes where the pressure is around 200mb (a few km above the surface) than it does at the surface. This leads to faster warming at these altitudes in the troposphere than at the surface, and produces a negative lapse rate feedback.

Credit : Figure 1 from Sherwood & Nishant (2015)

Credit : Figure 1 from Sherwood & Nishant (2015)


In general, it seems that this result is broadly consistent with climate models, but that there are some differences, such as it not reaching quite as high in the tropics and sub-tropics as predicted. I don’t quite understand the significance of this. I also don’t quite understand the significance of stratospheric trends being about half as strong as reported earlier. Maybe others who do could clarify in the comments. Overall, however, this seems to be an important results which appears to confirm our basic understanding. I’m looking forward to Turbulent Eddie accepting that we now have evidence for a tropospheric hot spot 😀

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83 Responses to Tropospheric hot spot?

  1. J says:

    This paper addresses the tropical troposphere hotspot using radiosonde data. Wasn’t there also a paper by Po-Chedley and Fu a month ago that addressed this using the MSU satellite data? It would be nice to see somebody put these two pieces together.

  2. MikeH says:

    More pecisely, the tropical tropospheric amplification?

    The Po-Chedley paper was discussed here where the term “tropospheric amplification” is used.
    http://www.theguardian.com/environment/climate-consensus-97-per-cent/2015/mar/25/one-satellite-data-set-is-underestimating-global-warming

  3. chris says:

    Po, Chedley and Fu? Is this going to be another thread about the Teletubbies?

  4. MikeH says:

    The Po-Chedley and Fu paper is in fact referenced in Sherwood & Nishant. See 1. Introduction.

  5. Christian says:

    ATTP,

    Sometimes, when People beginn to talk about “tropical Hotspot”, there is often missing, that this “Hot-Spot” doent have to be the same like in Models for now, because the “Hotspot” is a result of a idealized 2xCo2 experiments (havent see other experiments for now) and in that way and knowing about Aersols, i would not expect the totaly same looking “Hot Spot” like in Models.

    Please try me to correct if iam wrong

  6. Tom Dayton says:

    Mike Mann, on his FaceBook page, has explained that the existence of the hot spot actually is evidence against warming being due to one thing other than greenhouse gases. Here is the key quote:
    “What’s the punchline? Well, if global warming really *were* due to a (natural) decrease in volcanic activity over time (rather than due to an anthropogenic increase in greenhouse gases), then we would expect to see an increase in global surface temperatures WITHOUT any mid-tropospheric “hot spot”.”
    “In the end, then, the confirmation of a “hot spot” in this latest study by Sherwood and Nishant isn’t completely irrelevant to the issue of human-caused climate change. While it may not be a unique fingerprint of anthropogenic greenhouse gas increases, it does nonetheless potentially allow us to rule out at least one possible suspect (changes in volcanic activity). It turns out that anthropogenic changes in ozone (both tropospheric, as a surface pollutant, and stratospheric, as a result of stratospheric ozone depletion) are another potential “forcing” of climate change that does not have a clear “hot spot” signature as part of its fingerprint.”

  7. Tom,
    I think that’s because the volcanic influence is to increase/decrease stratospheric aerosols and, consequently, influences the amount of radiation reaching the surface. If it were Solar instead, then I think you’d see a “hot spot”. I must admit that I’m a little confused as to why changes in volcanic activity wouldn’t have an effect because I thought it was due to the temperature dependence of the moist adiabatic lapse rate and I don’t quite see why this wouldn’t also apply to a volcanic influence.

  8. Well, according to this Climate Dialogue post by Stephen Sherwood, it should not depend on what causes the warming:

    The implications for attribution of observed global warming are nil, as far as I can see. The regulation of lapse rate changes by atmospheric convection is expected to work exactly the same way whether global temperature changes are natural or forced (say, by greenhouse gases from fossil fuel burning).

  9. Michael 2 says:

    “I’m looking forward to Turbulent Eddie accepting that we now have evidence for a tropospheric hot spot”

    Provided he accepts that “iteratively homogenized … data” is evidence.

  10. Tom Dayton says:

    Mike Mann has a followup. I don’t know how to link to a particular FaceBook post, but it is the most recent post of his at this moment: https://www.facebook.com/MichaelMannScientist.

  11. Tom,
    Thanks. Sounds like there is still some disagreement. My understanding is that it is related to the dependence of the moist adiabatic lapse rate on temperature, so it would be interesting to know how we can warm in some circumstances without a hot spot, and in others with a hot spot. I notice that Chris Colose mentions tropospheric aerosols, so maybe that has a different effect to stratospheric aerosols.

  12. I’m looking forward to Turbulent Eddie accepting that we now have evidence for a tropospheric hot spot.

    Very good. I saw this paper last month.

    See if you can find the single word, used three times in the article, that tells you
    why this analysis differs from the mean RAOB data and the mean MSU ( both UAH and RSS ) data and which data might be more accurate:

  13. Christian says:

    ATTP,

    I argue on this point, that we now be on a transient state, some Model (ModelE by GISS) often given respones by fixed SST(more to Instant) and 100y-Responses(more to eqibrilium), its hard to find the rigth way to compare observation (which is transient) with Responses to fixed SST or 100y-Response.

    If you ask me, we know(with not so much certain) that Aersols can alter clouds properties and precipitation. Specially for troposheric Aerosols (parts which have not a long livetime) the effect is very regional then global. In GISS-ModelE there is a experiement with the troposheric Aerosols (1880-2000) with an 100y-Respone and there is also a “cool/hot-Spot” in the tropical midde atmosphere but weaker then the near Surface Response between 30-50N.

    See also here: http://data.giss.nasa.gov/tmp/modelE/efficacy/tmpjk.1.Rc.E2TRA.ANN_lin/pjmap.gif

    So yes i agure its not the same like vulcanic Aerosols, because SOx which is not exceeds tropopause has a very short lifte time and their effct is stronger to regional scale then global

  14. Some hints.
    It’s not a word one typically sees with respect to climate or climate change discussions.
    You would not be happy if this word was used in conjunction with surface data.
    And this word does not really apply to a middle of the road consensus approach.

  15. dikranmarsupial says:

    Turbulent Eddie you would probably make your case rather better by just explaining it for yourself. There comes a point where this sort of game becomes rather dull, and for me it reached that point after the first comment.

  16. OK, one final hint ( it’s only been a few minutes and someone might actually read the paper ).

    Mark Twain would not like this data.

  17. Inhomogeneities.

  18. A median is in the middle of the road, but not the middle of the road.

    I’m not a statistician, but I am suspicious when analysis throws out data.

    Beyond the big difference from other analyses, there is also the difference with MSU data.
    There are also some other interesting differences with this set and both the models and observations.
    1. Arctic amplification appears to be missing in this paper while both models and other obs appear to agree.
    2. Models and obs have maximal stratospheric cooling in the upper stratosphere while this paper seems to have less stratospheric cooling at 30 mb than at 50mb
    3. Models and obs appear to agree on a slot of no change over the Souther Oceans ( ~ 60S ) but this paper has upper tropospheric warming there.

    I think this paper merely represents statistical artefacts based on arbitrary statistical definitions of what ‘good’ stations are.

  19. Brandon Gates says:

    TE,

    I think this paper merely represents statistical artefacts based on arbitrary statistical definitions of what ‘good’ stations are.

    Perhaps because you’re suspicious and not a statistician.

  20. BBD says:

    TurbEd

    What exactly is your point? What wider conclusions do you think this study supports or undermines? Why should we care?

  21. Brandon Gates says:

    BBD,

    What wider conclusions do you think this study supports or undermines?

    It denies The Pause, which is generally fatal: Moreover our data do not show any slowdown of tropical atmospheric warming since 1998/99, an interesting finding that deserves further scrutiny using other datasets.

  22. BBD says:

    TurbEd

    why this analysis differs from the mean RAOB data and the mean MSU ( both UAH and RSS ) data and which data might be more accurate:

    Did you do that Christy thing where you average the RSS and UAH (stratospheric-influenced cold-biased) tropical MT data even though they differ by a factor of three?

    Did you do that? 😉

  23. Brandon Gates says:

    TE,

    Beyond the big difference from other analyses, there is also the difference with MSU data.

    1) Which other analyses? Why should those other analyses necessarily be more correct?
    2) One big difference between radiosonde and MSU data is that the latter have far coarser vertical resolution. Another is that radiosondes directly measure temperature in situ whereas satellites clearly do not. It may be an advantage of microwave sounding from space that the data density is higher than that of the balloon-based instruments, however:

    Satellite sounders available since 1979 can provide some constraint on the vertical variation of warming, but only in the form of broad weighted averages that span much of the troposphere and/or stratosphere. These data have been interpreted as indicating too little warming trend in the upper compared to the lower troposphere (Fu et al 2011, Po-Chedley and Fu 2012) and one satellite product shows less warming in the atmosphere than at the surface (Christy et al 2010). Caution is warranted however because the satellites suffer from uncertain changes over time in calibration and other inhomogeneities, exacerbated by the manipulations of the data necessary to extract the signals of concern here (CCSP 2006). Another problem is that warming trends in the upper troposphere are easily corrupted by the much larger cooling trends in the lower stratosphere (Fu et al 2004), the profile of which varies significantly among different observational records (Sherwood et al 2008); indeed Fu et al (2004) and Fu and Johanson (2005) concluded that MSU-observed tropical warming was consistent with a moist-adiabatic change profile. Meanwhile MSU products targeting the lower troposphere are strongly affected by the surface, which may warm differently. Recent findings suggest that overall global warming rates in the troposphere have been too weak in some previous studies due to characterization of the diurnal cycle and imprecise corrections for calibration errors (Po-Chedley et al 2015). This suggests that the stronger warming in the upper troposphere shown by some recent radiosonde datasets may indeed be correct. More independently generated datasets are needed to verify whether the stronger warming shown by some is correct, and to extend these from 1959 through to recent times.

    So the jury is still out.

    I find no references to throwing out any data. Perhaps you could point to the specific text of the paper which leads you to believe that any data have been discarded.

  24. TE,

    See if you can find the single word, used three times in the article, that tells you
    why this analysis differs from the mean RAOB data and the mean MSU ( both UAH and RSS ) data and which data might be more accurate:

    Rather than throwing out hints, why not just tell us what you it is.

  25. Eli Rabett says:

    Different forcings have different fingerprints. For example solar forcing heats the stratosphere, greenhouse gas forcing cools it (as do CFCs). An interesting idea about looking for solar forcings would be to look at cloud top temperatures because an increase in solar forcing would warm them.

  26. Eli,
    Yes, I realised that the different forcings have different fingerprints, but I wasn’t aware that they would produce a different lapse rate dependence on temperature?

  27. Eli Rabett says:

    Sorry, not clear, you look for the fingerprint characteristic of the expected forcing. So if you say that solar forcing and GHG forcing would both be characteristic of a tropospheric hot spot, and no other forcings, you look for something that can distinguish between the two like stratospheric cooling (also seen in Sherwood).

  28. Eli Rabett says:

    If Sherwood holds up what does that do to the calibration of UAH?

  29. Eli,
    Ahh, okay, yes I agree. The discussion, though, was about Michael Mann suggesting that warming due to a reduction in volcanic aerosols would not produce a hot spot. I wasn’t sure if this was right or not.

  30. If Sherwood holds up what does that do to the calibration of UAH?

    Yes, I’d wondered the same. Po-Chedley & Fu also suggests and issue, I think.

  31. Paul S says:

    Turbulent Eddie,

    1. Arctic amplification appears to be missing in this paper while both models and other obs appear to agree.

    I think maybe your eyes are being tricked by the difference in vertical scales used. However, North of 75ºN radiosonde data is very scarce so trends probably aren’t very reliable there. Similarly for the Southern Ocean – no radiosonde stations there.

    2. Models and obs have maximal stratospheric cooling in the upper stratosphere while this paper seems to have less stratospheric cooling at 30 mb than at 50mb

    Not sure where your obs are coming from? None of the obs images you’ve presented here resolve between 30mb and 50mb. MSU datasets are unsuitable for distinguishing trend differences at these levels so radiosondes is it at the moment. If there are differences from other radiosonde datasets that would be interesting but not necessarily a reason to discount these results.

    Also worth considering that the trend cross-section is for the period 1960-2012, not 1980-2014 as you’ve used. There will be differences due to the influence of El Chichon eruption and timing of Ozone depletion.

    ————————————————–
    I’m not really convinced there’s anything hugely new here, nor that there is necessarily much discrepancy between these results and those from other observations once you take into account differences in what’s actually being measured – e.g. trend periods, geographical coverage, vertical atmospheric weighting.

    Regarding the non-pause in the Tropics, a key issue with radiosondes is sparse coverage. Of particular relevance here, there is a lack of data in the Eastern Pacific, which is a problem because that’s been the main region of tropical cooling over “the slowdown” period. Comparing global tropics with tropics 90W-180E (i.e. cutting out East Pacific) in surface data I find they agree quite well over 1960-1995 but show a substantial divergence thereafter, such that the latter averages about 0.1ºC greater warming over 1997-2012. I suspect coverage bias is the main cause of the non-pause result.

  32. If Sherwood holds up what does that do to the calibration of UAH?

    And RSS.
    And RATPAC.
    And Hadley.
    And…

    It doesn’t mean Sherwood is wrong but it is odd man out.

  33. TE,
    Why is Sherwood relevant to the surface temperature datasets?

  34. Eli Rabett says:

    UAH calibrates against radiosondes

    RSS does not, same with the rest. They may have their own problems, but radiosondes are not one of them

  35. No, but as I display in the graphic (ad nauseum) above, UAH,RSS, and RATPAC ( and other sonde data sets ) tend to look about the same and confirm some aspects of the GCMs but not the hot spot.

  36. Also worth considering that the trend cross-section is for the period 1960-2012, not 1980-2014 as you’ve used. There will be differences due to the influence of El Chichon eruption and timing of Ozone depletion.

    Dman good point.

    Guess I’ll have to have a closer look.

  37. Dman it, I mean damn.

  38. Regarding fingerprints,

    RATPAC-RSS-UAH compared to models:

    ✓ Tropospheric Warming,
    ✓ Stratospheric Cooling,
    ✓ Arctic Maxima
    ✓ Little Atmospheric Change Over Southern Oceans
    ✗ Hot Spot

    Not too bad, really.

  39. BBD says:

    TurbEd

    And your point is… ?

  40. Brandon Gates says:

    BBD,

    Oh who knows. As for the three instances of a dirty word, here’s my guess for the offending passage:

    2.2. Modifications for this study

    Several modifications have been made for IUKv2.

    First, we found and corrected two minor bugs affecting how data were smoothed before computing EOFs. Fortunately this had very little impact on results.

    Second, we include two pressure levels (700 and 400 hPa) that were omitted in the original dataset. The reason they were omitted before was to give equal weight to the troposphere and stratosphere in detecting change points; here, we omit these levels only during change-point detection, while still including them subsequently. Multi-level changes points detected from the other levels are also assumed to exist at these two levels.

    Third, we no longer carry out the third step of change-point detection nor provide data for stations reporting only once per day. This is because the homogenization of these stations was judged to be unreliable, and they were typically not used. The original study found that the final step and associated round of homogenization did not have a significant effect on the results at twice-daily stations.

    The associated Twain quote might be: Get your facts first, and then you can distort them as much as you please.

    I thought at first this might have been what caught his eye: Caution is warranted however because the satellites suffer from uncertain changes over time in calibration and other inhomogeneities, exacerbated by the manipulations of the data necessary to extract the signals of concern here (CCSP 2006).

    Except that “dirty” word only appears once. Other than this puzzler and an ironic appeal to odd-men out he’s not got much going … other than assiduously ignoring that MSUs don’t resolve trends in the pressure levels of interest as well as radiosondes do.

    To be fair, I stand corrected for not recognizing at first read that data from once-daily reporting stations were indeed excluded.

  41. BBD says:

    Thank you, BG

    Pending clarification from TurbEd, I shall go to bed.

  42. Get some shuteye BBD, you deserve it.

    I’ve gotta do the dishes, then I’ll turn in too.

  43. Steven Mosher says:

    Eddy

    “I’m not a statistician, but I am suspicious when analysis throws out data.

    Beyond the big difference from other analyses, there is also the difference with MSU data.”

    1. I am suspicious when an analyst Keeps data without First checking that the observational
    conditions are relatively homogenous.
    2. You NEVER complained about Sherwoods previous versions when he also omitted data.

    3. MSU data cannot be compared with Sonde data. One measures temperature IN SITU
    the other measures brightness, and INFERS temperature from that.

    Then there is this:

    Guess the author

    ““[8] We examined the data records of the 183 tropical
    stations available in the Integrated Global Radiosonde
    Archive (IGRA) database at the National Climatic Data
    Center [Durre et al., 2005]. To use a sonde profile to
    simulate LT, we required that it reach at least 100 hPa. To
    include a station, we required that it have at least 180 of the
    possible 312 months of data. Enforcing these criteria
    reduced the number of stations to 73. Comparing the sonde
    and satellite series for consistency we eliminated the 43000
    block (India) as being unacceptably noisy (as in Parker et
    al. [1997] and Lanzante et al. [2003]). We were left with the
    58 stations shown in Figure 1 and described in Tables S1
    and S21
    . Of these, 29 provided observations for both day
    and night, 28 for day only, and one for night only. ”

    That would be Spencer!!!!

    what is the point. When spencer goes to compare and calibrate his product to Sondes, you see the kinds of omissions he has to make. you were never suspicous, you accepted the UHA data because you liked the answer.

  44. Peter Thorne says:

    ATTP,

    having been in this game since my PhD … in the tropical troposphere the only vertical mixing show in town is convection so folks are throwing you curve balls here. Whatever happens at the surface gets amplified aloft. So, the volcanic recovery signal would lead to a hotspot (over the short period but on multi-decadal timescales the trend would be zero …) for example. See Mitchell et al., 2013, GRL for how a whole bunch of models collapse on one another when you change the viewing angle from absolute temperatures to amplification which is the physically constrained aspect. The surface is the energy source and the rest is convection. This really is physics 101. The tropical hot spot is a first-order physical manifestation of a warming surface, and a tropical cool spot would be a first order manifestation of a cooling surface. It has zero to do with forcing and everything to do with dynamics.

    It is hard to see a mechanism whereby some other factor could come into play here as that mechanism would somehow have to change the density of the troposphere and we’d know about it by now because the physical effects would be observable and have been debated ad nauseum. If it did then it fundamentally would challenge our understanding of and ability to model half the global atmosphere (the tropics) and understand their circulation. My mortgage is on amplification here all the way …

  45. Peter,

    in the tropical troposphere the only vertical mixing show in town is convection so folks are throwing you curve balls here. Whatever happens at the surface gets amplified aloft. So, the volcanic recovery signal would lead to a hotspot

    Thanks, that’s kind of what I thought. This started with Michael Mann claiming on facebook that it wouldn’t. It seems that his latest update has modified this slightly.

  46. folks are throwing you curve balls here

    Is it folks here? or mother nature? or GCM fidelity?

    The case for GCM unfaithfulness is pretty easy.

    The ITCZ is fairly narrow:

    and the thunderstorms within are smaller still so as to be sub-gridscale.

    That does also mean that radiosonde soundings very poorly capture the convection zones of the tropics, however the ‘Hot Spot’ is modeled to be of a fairly broad band ( 30S to 30N ).

    Do the parameterizations for a 1degree by 1degree grid cell accurately reflect the total convection within? With Northern Summer approaching, those in North America can go here:
    http://weather.rap.ucar.edu/upper/
    to check each morning’s local parameterizations and try there own hand at forecasting thunderstorms in their area. After a summer of this, reassess your faith in GCM modeling of convection. Is a very small but intense thunderstorm the same as four weak but widespread thunderstorms within a grid cell?

    Then reflect that the ITCZ represents the convergence of polar air masses from each hemisphere.


    The convergence is chaotic which means divergence from actual conditions the longer a model runs. The small divergences provide feedback to further variance from actual but do they amplify into longer term variations? Observations of decadal and centennial scale variations suggests that they do.

    Another consideration of the HotSpot is heating and humidifying the tropical upper troposphere will increase the cooling rate of that spot. The hotter the spot, the faster it will cool, which should lead to further convective transfer which should lead to a hot spot which should enhance cooling, which…. Convection and radiance are locked in epic battle. Slight miscalculation of this struggle through resolution or non-linearity could exhibit a different response.

    It would not be surprising if the known unpredictable features of GCMs ( the dynamics ) failed to verify in some ways. This doesn’t require some missing process or invalid physics, just the same old boring shortcomings ( resolution and non-linearity ) that have plagued the endeavour from the beginning.

  47. izen says:

    @- TE
    Turns out GCMs model the ITCZs quite accurately….

    http://www.clidyn.ethz.ch/papers/Bischoff-Schneider-2014.pdf

  48. Steven Mosher says:

    Peter,

    “See Mitchell et al., 2013, GRL for how a whole bunch of models collapse on one another when you change the viewing angle from absolute temperatures to amplification which is the physically constrained aspect. The surface is the energy source and the rest is convection. This really is physics 101. The tropical hot spot is a first-order physical manifestation of a warming surface, and a tropical cool spot would be a first order manifestation of a cooling surface. It has zero to do with forcing and everything to do with dynamics.”

    Thanks for that! very clear

  49. Steven Mosher says:

    Eddy ,

    “folks are throwing you curve balls here”

    Eddy.. you threw the first curveball with a vague attack on the data. Of course you had nothing to back it up, which is why you launched a vague attack. You couldnt actually call any the specific decisions into question, so you questioned the whole process of cleaning data. When it was pointed out to you that the data you like to use has ALSO been through a process of adjustment you ran away.

    Two position for you are possible.

    A) you attack all attempts to QC data and demand only raw data, in which case many if not all of the sources you rely on fall to bits.
    B) you make specific criticisms of Sherwood’s choices.

    Path A is the stupid pet trick and it really precludes you from saying anything about anything.
    Path B is how obseration science moves forward. Data is usually a mess and step one is doing a compentent defensible job of making tough data analysis choices.

    So, Choose.

    or change the subject.

  50. izen,

    Interesting paper which more or less indicates what I said – tropical convection fluctuates as a result of variation in the unpredictable general circulation.

  51. Eddy.. you threw the first curveball with a vague attack on the data. Of course you had nothing to back it up, which is why you launched a vague attack. You couldnt actually call any the specific decisions into question, so you questioned the whole process of cleaning data. When it was pointed out to you that the data you like to use has ALSO been through a process of adjustment you ran away.

    Two position for you are possible.

    A) you attack all attempts to QC data and demand only raw data, in which case many if not all of the sources you rely on fall to bits.
    B) you make specific criticisms of Sherwood’s choices.

    Path A is the stupid pet trick and it really precludes you from saying anything about anything.
    Path B is how obseration science moves forward. Data is usually a mess and step one is doing a compentent defensible job of making tough data analysis choices.

    So, Choose.

    Mosher, it’s interesting you are so defensive of Sherwood data without being familiar with it.

    You are correct that all data needs to be QC’d.

    But do consider, one of the first things they tell newbie weather forecasters is “don’t forecast record breaking events” – the logic being that extreme events are not likely.

    There’s a problem, however. Weather records are routinely broken. When one QC’s data on the basis of variance, that pre-supposes that variance determines accuracy – not valid when measuring physical phenomenon. Doing so includes all the stations with smaller errors, perhaps excluding stations with valid but exceptional data.

    To be fair, I am not intimately familiar with the IUK, though I’m going to take a look. Unfortunately the series is not up to date and didn’t, as far as I saw, include comparable statistics to other sonde data sets which means writing some analysis code.

    If you beat me to it with your analysis, have at it.

    Now, my initial reaction is somewhat based on the claim of displaying a hot spot based on different periods of analysis ( 1960 to 2012 ) versus the satellite era ( 1979 to present ). Using the satellite era allows for comparison with MSU analyses. Did the hot spot disappear over the last third century? Possible. Or are the models incorrect because the hot spot is a function of weather, weather is determined by non-linear partial differential equations, the solutions and fine scale approximations of which are known not to be predictable.

    You decide.

  52. izen says:

    It all seems so long ago… I can barely remember,!

    Back in the distant past, when it was still credible to have doubts about the actual behaviour of the climate despite the physics of AGW, there had been cooling (an ice age cometh!) and the analysis of weather station data to try and detect small climate trends was just starting. Then the first decade of satellite observations showed cooling.

    The underlying process of tropical amplification was evident in the lapse rate, but with a cooling trend the tropical tropospheric hot-spot amplification predicted by climate models, was obviously NOT evident in the data.
    While there were doubts about the growing discrepancy between surface measurements and satellite data, the radio-sonde data seemed to support the satellite data.
    however the sonde data was known to have problems.
    As I think Victor mentioned up-thread sonde thermometers in the past might be rather more indicative of radiant warming of the housing that the ambient air temperature.

    However even back in those days the absence of a tropical hot-spot trend was flourished as the final nail in the AGW theory coffin.

    As Radio-sonde data improved and re-analysis of past data developed the discrepancy between the satellite observations and the other sources of global temperature data became more problematic. After an official investigation, and several adjustments, corrections and improvements in the satellite data record that brought it more in line with the warming observed by other methods, it was judged that the discrepancies were within the observational errors of the various methods, with the clear implication that the satellite record was the more dubious of the options.

    If I remember rightly Christy and Spencer claimed at one point that their very low warming trend was credible because it was similar to the trend seen in the historical radio-sonde data.
    Glossing over the fact that they used that selected sonde data to calibrate the corrections and derive tropospheric temperatures from the sensor observations.

    It was generally recognised that the data required to detect the trend in the tropical tropospheric hot-spot (TTHS) was not available with present methods or from past observations.

    This has not prevented the inability to show a TTHS from still being flourished as the (un)-smoking gun that kills off AGW… as sen in this thread.

    A few years ago I think, there was analysis of sonde and satellite observations that detected the TTHS trend over the course of a Julian-Madden event and there is also evidence of the effect predicted in models during an ENSO transition. However clear detection of a TTHS tremd on a ~third of a degree shift within a few months is obviously easier than detecting the trend from 0.75degC over ~60 years.

    Modern sonde data may be better, but detecting a TTHS trend is still dependent on deriving a credible set of data from the past problematical record. Satellite observations are inherently unable to resolve in sufficient vertical detail to provide significant data on a TTHS. In part because their vertical separation of temperatures from the sensor observations is rooted in those same sonde records, but with a further uncertainty in just WHAT altitude or pressure band their derived temperature refers to.

    I am however fully confident in the versatility and creativity of voodoo science. Even if the TTHS trend is unequivocally detected and attributed to AGW I am sure that there will be some zombie/vampire argument that a discrepancy or uncertainty is the final stake through the heart of AGW…

    Some people are always sceptical, I think Fred Singer is still dubious of all those ‘corrections’ Spencer and Christy made to the UAH satellite record and still uses version 1 or 2 that shows cooling.

  53. However even back in those days the absence of a tropical hot-spot trend was flourished as the final nail in the AGW theory coffin.

    Well, that’s not what I think at all.

    In fact,
    ✓ Tropospheric Warming,
    ✓ Stratospheric Cooling,
    ✓ Arctic Maxima
    ✓ Little Atmospheric Change Over Southern Oceans
    ✗ Hot Spot

    The two features from strictly radiative factors ( tropospheric warming and stratospheric cooling ) do tend to confirm AGW.

    And the slot of little change over the Southern Oceans gives credence to the dynamics there anyway.

    The Arctic Amplification would seem a little less certain, because it seems to be regulated by Arctic Sea ice which appears to have varied in the past and has some portion which is natural.

    But all these features are borne out by previous sonde analysis and RSS as well as UAH MSU analysis.

    So the lack of a hot spot doesn’t disprove AGW at all.

    Now, what it might do is indicate some lessening of the expected rate of AGW.

    How?

    Most car engines are almost closed heat systems. Heat is generated in the engine by combustion and carried by the convection of ‘coolant’ to the misnamed ‘radiator’ which sheds heat and returns ‘coolant’ back to the engine. Two factors can control the engine temperature:
    1. The rate of convective transfer ( if the ‘water pump’ goes out, the engine overheats ) and
    2. The cooling rate of the radiator ( if the radiator fan stops turning the radiator cools less and … )

    The atmosphere may be similar. Heat is generated at the surface by net radiative gain. Heat is carried aloft through convection where it is more readily radiated to space. Increases in the rate of convective heat transfer and the rate of cooling aloft may reduce some of the imbalance imposed by radiative forcing from CO2.

  54. Heat is generated at the surface by net radiative gain. Heat is carried aloft through convection where it is more readily radiated to space. Increases in the rate of convective heat transfer and the rate of cooling aloft may reduce some of the imbalance imposed by radiative forcing from CO2.

    You’re essentially arguing for a more negative lapse rate feedback.

  55. izen says:

    @-TE
    “tropical convection fluctuates as a result of variation in the unpredictable general circulation.”

    I am not sure in what sense you can regard the general circulation as ‘unpredictable’.
    As a perusal of Isaac Held’s blog, (which seems to be back up,) would show, modelling can ‘predict’ the general circulation at the global scale very well.
    http://www.gfdl.noaa.gov/blog/isaac-held/2013/10/21/42-aqua-planet-hurricanes-and-the-itcz/
    It is after all shaped by Coriolis forces and constrained by 2nd LoT.
    Lots of local turbulence, and sea-land distribution has big effects, but that limits models to projecting the envelope of behaviour at the less predictable regions.
    Clearly defined bounds of doubt and uncertainty!

  56. izen,
    Indeed, I had thought that GCMs did global circulation well. I think Steve Easterbrook’s TED talk illustrates this well.

  57. BBD says:

    So the lack of a hot spot doesn’t disprove AGW at all.

    What ‘lack’ of a hotspot? WTF is Eddie on about?

    He just carries on with the same old bullshit regardless of the evidence.

  58. John Hartz says:

    Another piece of the puzzle has been solved…

    Scientists have zeroed in on the tropical Pacific as a major player in taking up that heat. But while it might have held that heat for a bit, new research shows that the Pacific has passed the potato to the Indian Ocean, which has seen an unprecedented rise in heat content over the past decade.

    The new work builds on a series of papers that have tracked the causes for what’s been dubbed the global warming slowdown, a period over the past 15 years that has seen surface temperatures rise slower than they did the previous decade. Shifts in Pacific tradewinds have helped sequester heat from the surface to the top 2,300 feet of the ocean. But unlike Vegas, what happens in the Pacific doesn’t stay in the Pacific.

    Heat is Piling Up in the Depths of the Indian Ocean by Brian Kahn, Climate Central, May 18, 2015

  59. FWIW, I downloaded the IUK data and ran some statistics.
    Here’s the comparison using 1979-2012:

  60. TE,
    What are your figures illustrating? You really do need to explain what you post. You seem to be showing a “hot spot” from the model – on the left – and then various other things on the right which you haven’t explained.

  61. dhogaza says:

    Summary of TE:

    Science proven wrong once again by a random internet person posting a random graphic on a random (sorry, ATTP) blog.

  62. dhogaza,
    Well, I’m not sure. The paper I mention here suggests observations indicate a surface warming of 1.4K/century and a tropospheric warming (at 300hPa) of 2.5K/century. Seems broadly consistent with the GISS model that TE shows (left-hand figure).

  63. I guess it’s been a really long time since I looked at the map of surface temperature trends.
    I didn’t realize how much of the Pacific has a cooling trend since 1979:

    Given the cooling, and lessened tropical SST trends overall, one would not expect a hot spot.

    The problems with the models may not be so much that sea surface and upper tropospheric temperatures are coupled but that the models don’t predict the quite striking PDO signature.

  64. JCH says:

    Exactly. Since 1980 the PDO has been progressively fighting the AGW signal. In the 200s the PDO finally went into a cool phase and it has caused the unspeakable: the pause.

    So contrary to what everybody s saying, the AMO/Girma/Lewis crowd, ACO2 has had to overcome the declining PDO index, natural variation, since 1980.

    And that is likely over with as the PDO went sharply positive in 2013. Right on schedule. It drives the global mean surface temperature, so it went up in lock step.

    We’re about to see aggressive warming.

  65. It’s possible. However, PDO doesn’t appear to be regular or periodic and is certainly unpredictable:
    http://upload.wikimedia.org/wikipedia/commons/0/09/PDO.svg
    A reminder from this is that the GCMs don’t have accurate representation of the PDO, ENSO, AMO, et. al..

  66. JCH says:

    Well, they do. Over decades, It averages to near zero.

  67. Marco says:

    “Given the cooling, and lessened tropical SST trends overall, one would not expect a hot spot.”

    http://data.giss.nasa.gov/cgi-bin/gistemp/nmaps.cgi?sat=-1&sst=3&type=trends&mean_gen=0112&year1=1979&year2=2014&base1=1951&base2=1980&radius=250&pol=rob

    Look at the bottom map. Trends in the tropical region is around .2/.3
    HadSST gives a little bit lower, but still warming.

  68. Look at the bottom map. Trends in the tropical region is around .2/.3
    HadSST gives a little bit lower, but still warming.

    Yes.

    The GISS model predicts 2 to 3 times that rate of warming for the tropics at the surface,
    so it’s not surprising if there’s not a hot spot, but still consistent with convective coupling.

    It’s a reminder ( as if anyone needed it ) that the GCMs can’t predict weather and by weather, we include multi-decadal oscillations.

  69. BBD says:

    Over the C20th for example.

  70. Marco says:

    TE, thanks for the nonresponse.

  71. Marco?

    You pointed out that the surface warming in the tropics is two to three times less than modeled.

    I agree.

    This raises questions on whether one should expect a hot spot – or not.

  72. Marco says:

    “You pointed out that the surface warming in the tropics is two to three times less than modeled.”

    That is not what I pointed out.

    You also again make claims without providing references.

  73. I have a question about Christy’s hotspot report. I’ve asked this question in multiple places, but still have not gotten a good answer from any of Christy’s defenders. So I thought you might be interested.

    Please see pages 24 and 25 of Christy’s report:
    https://thsresearch.files.wordpress.com/2017/04/ef-data-research-report-second-editionfinal041717-1.pdf

    Christy presents “tropical stratospheric” temperature data at a pressure of 150mb, with no cooling trend. But that pressure level is for the tropical tropopause, not the stratosphere, as shown in:
    “Tropical Tropopause Layer” [doi:10.1029/2008RG000267]

    So in order to avoid addressing stratospheric cooling (one of the hall-marks of CO2-induced global warming), Christy tries to pass off tropopause temperature as being stratospheric temperature. Isn’t that misleading?

  74. Atomsks,
    I haven’t had a chance to read it in detail, but the whole thing seems rather misleading. This, for example, isn’t really correct

    Stated simply, first, the THS is claimed to be a fingerprint or signature of atmospheric and Global Average Surface Temperatures (GAST) warming caused by increasing GHG/CO2 concentrations2.

    The Hot Spot is not a signature of warming caused by increasing GHG/CO2 concentrations, it is simply a signature of any kind of surface warming (increased evaporation and increased deposit of latent heat in the atmosphere). Also, as Michael Mann pointed out in his congressional testimony recently, if there is no hot spot (or it’s weaker than we expect) it actually suggests that we’re more sensitive than we expect because it would indicate that the lapse rate feedback (which is negative) is weaker than we expect.

  75. Actually, that report is even more bizarre than I at first thought. It seems to have some kind of process for removing natural influences, which then leads to virtually all the temperature datasets showing almost no warming since about 1960 and then concluding that CO2 has no influence on temperature.

  76. JCH says:

    Two years ago:

    So contrary to what everybody s saying, the AMO/Girma/Lewis crowd, ACO2 has had to overcome the declining PDO index, natural variation, since 1980.

    And that is likely over with as the PDO went sharply positive in 2013. Right on schedule. It drives the global mean surface temperature, so it went up in lock step.

    We’re about to see aggressive warming.

  77. …and Then There’s Physics,

    Yup. The “report” uses a cumulative ENSO index and cumulative TSI index to subtract out the warming. That makes no sense. Anyway, I wanted you to know that I have an answer to the questions I asked you: Christy is simply contradicting himself.

    In the 1st edition of his “report”, Christy claims that 150mb is the tropical upper troposphere:
    “On the Existence of a “Tropical Hot Spot” & The Validity of EPA’s CO2 Endangerment Finding” (page pages 23, 25, and 59):
    https://thsresearch.files.wordpress.com/2016/09/wwww-ths-rr-091716.pdf

    But in the 2nd edition of his report, he claims that 150mb is the tropical stratosphere:
    “On the Existence of a “Tropical Hot Spot” & The Validity of EPA’s CO2 Endangerment Finding, Abridged Research Report, Second Edition” (pages 24, 25, and 70):
    https://thsresearch.files.wordpress.com/2017/04/ef-data-research-report-second-editionfinal041717-1.pdf

    So in the transition from the 1st to the 2nd edition, Christy re-labelled upper tropospheric temperature as stratospheric temperature, with the effect of making it look like the stratosphere warmed. He did this despite the fact that the stratosphere actually cooled (as shown in the very source Christy cited in his “report”). Christy’s re-labeling is convenient for his position, because Christy’s solar warming hypothesis implies stratospheric warming. Furthermore, CO2-induced global warming would result in stratospheric cooling, and Christy’s “report” is committed to saying that CO2 has had no significant impact on temperature records.

    Normally I like to give people the benefit of the doubt, especially well-credentialed scientists like Christy. But what Christy did here is beyond the pale for me. This looks like a clear instance of Christy distorting the facts in a way that fits his preferred narrative. I’m surprised that he would cite such a distorted “report” to the US Congress:
    “U.S. House Committee on Science, Space & Technology, 29 Mar 2017, Testimony of John R. Christy” (pages 10 and 11):
    https://science.house.gov/sites/republicans.science.house.gov/files/documents/HHRG-115-SY-WState-JChristy-20170329.pdf

  78. Also wanted to mention a few other papers that found the hot spot, along with the data sources for the papers (I think you already posted paper #6 in your discussion):

    In satellite data:
    #1 : “Contribution of stratospheric cooling to satellite-inferred tropospheric temperature trends”
    #2 : “Temperature trends at the surface and in the troposphere”
    #3 : “Removing diurnal cycle contamination in satellite-derived tropospheric temperatures: understanding tropical tropospheric trend discrepancies”, table 4
    #4 : “Comparing tropospheric warming in climate models and satellite data”, figure 9B

    In radiosonde (weather balloon) data:
    #5 : “Internal variability in simulated and observed tropical tropospheric temperature trends”, figures 2c and 4c
    #6 : “Atmospheric changes through 2012 as shown by iteratively homogenized radiosonde temperature and wind data (IUKv2)”, figure 1 and 2
    #7 : “New estimates of tropical mean temperature trend profiles from zonal mean historical radiosonde and pilot balloon wind shear observations”, figure 9
    #8 : “Reexamining the warming in the tropical upper troposphere: Models versus radiosonde observations”, figure 3 and table 1

    In re-analyses:
    #9 : “Detection and analysis of an amplified warming of the Sahara Desert”, figure 7
    #10 : “Westward shift of western North Pacific tropical cyclogenesis”, figure 4b
    #11 : “Influence of tropical tropopause layer cooling on Atlantic hurricane activity”, figure 4
    #12 : “Estimating low-frequency variability and trends in atmospheric temperature using ERA-Interim”, figure 23 and page 351

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