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UAH Release Version 6.0 – Confirms Cooling Trend Since 1998

April 28, 2015



By Paul Homewood


h/t AC Osborn


Roy Spencer reports that, after three years of hard work, UAH have now released the new Version 6.0 temperature dataset. The main result is that the new version reduces the warming trend since 1979 from 0.140C to 0.114C/decade.



Version 6 of the UAH MSU/AMSU global satellite temperature dataset is by far the most extensive revision of the procedures and computer code we have ever produced in over 25 years of global temperature monitoring. The two most significant changes from an end-user perspective are (1) a decrease in the global-average lower tropospheric (LT) temperature trend from +0.140 C/decade to +0.114 C/decade (Dec. ’78 through Mar. ’15); and (2) the geographic distribution of the LT trends, including higher spatial resolution. We describe the major changes in processing strategy, including a new method for monthly gridpoint averaging; a new multi-channel (rather than multi-angle) method for computing the lower tropospheric (LT) temperature product; and a new empirical method for diurnal drift correction. We also show results for the mid-troposphere (“MT”, from MSU2/AMSU5), tropopause (“TP”, from MSU3/AMSU7), and lower stratosphere (“LS”, from MSU4/AMSU9). The 0.026 C/decade reduction in the global LT trend is due to lesser sensitivity of the new LT to land surface skin temperature (est. 0.010 C/decade), with the remainder of the reduction (0.016 C/decade) due to the new diurnal drift adjustment, the more robust method of LT calculation, and other changes in processing procedures.


1. Introduction & Some Results

After three years of work, we have (hopefully) finished our Version 6.0 reanalysis of the global MSU/AMSU data. Many procedures have been modified or entirely reworked, and most of the software has been rewritten from scratch. (Please, before you ask a question, read the following to see if your question has already been answered.)

The MSU and AMSU instruments measure the thermal microwave emission from atmospheric oxygen in the 50-60 GHz oxygen absorption complex, and the resulting calibrated brightness temperatures (Tb) are nearly equivalent to thermometric temperature, specifically a vertically-weighted average of atmospheric temperature with the vertical weighting represented by “weighting functions”.

One might ask, Why do the satellite data have to be adjusted at all? If we had satellite instruments that (1) had rock-stable calibration, (2) lasted for many decades without any channel failures, and (3) were carried on satellites whose orbits did not change over time, then the satellite data could be processed without adjustment. But none of these things are true. Since 1979 we have had 15 satellites that lasted various lengths of time, having slightly different calibration (requiring intercalibration between satellites), some of which drifted in their calibration, slightly different channel frequencies (and thus weighting functions), and generally on satellite platforms whose orbits drift and thus observe at somewhat different local times of day in different years. All data adjustments required to correct for these changes involve decisions regarding methodology, and different methodologies will lead to somewhat different results. This is the unavoidable situation when dealing with less than perfect data.

After 25 years of producing the UAH datasets, the reasons for reprocessing are many. For example, years ago we could use certain AMSU-carrying satellites which minimized the effect of diurnal drift, which we did not explicitly correct for. That is no longer possible, and an explicit correction for diurnal drift is now necessary. The correction for diurnal drift is difficult to do well, and we have been committed to it being empirically–based, partly to provide an alternative to the RSS satellite dataset which uses a climate model for the diurnal drift adjustment.




Roy has the full technical detail behind the changes here.


As the graphs show, most of the changes have been since around 2003, which is significant as this brings the recent trends much more into line with RSS, which has been showing a cooling trend.


No doubt, the changes will be criticised in some areas, but such criticisms will be difficult to sustain when set against the RSS results. As the chart below shows, the two datasets now track pretty closely since 1998, and both show similar cooling trends.





The changes also demote 2014, which ranked the 3rd warmest on the old version, down to only the 6th warmest, again in line with RSS.




The new version, along with RSS, brings into even more clarity the sharp divergence since 1998 between the satellite and surface datasets – the elephant in the room which the climate establishment is so desperate to ignore.

  1. April 28, 2015 6:32 pm

    ‘the sharp divergence since 1998 between the satellite and surface datasets – the elephant in the room which the climate establishment is so desperate to ignore’

    Sounds like ‘hide the decline’ time again.

  2. mkelly permalink
    April 28, 2015 6:59 pm

    As E= hv this 50-60 Ghz emissions they are measuring have more energy than the Mhz that the CO2 puts out plus there are what 250 times more O2 in the atmosphere than CO2. Where is that difference counted in the energy budget?

  3. April 28, 2015 7:05 pm

    I don’t want to say it….
    …but I told you so….
    [UAH was not agreeing with 4 other “global” data sets from 2002; actually 7 data sets , if I include my own]
    Unfortunately it looks like WFT has not yet updated to UAH version 6

    • April 28, 2015 8:33 pm

      Wft seem well behind on everything. I emailed Paul but it bounced back

      • April 28, 2015 8:39 pm

        I got that same impression. Looks to me he’s gone surfing…

  4. April 29, 2015 7:37 am

    Much of this seems to be argument over which dubious data set is correct and what it means. It strikes me that the interesting value on the graph is 1998 which followed a fairly fast rise in the rate of change of the difference; it was this period that made global warming seem credible and allowed the predictions of Armaggedon to become news.

    Once a bogey-man has been created it is difficult to destroy it, and with our press and the churches ( just saw your blog on the Vatican censorship) self-censorship of criticism, the public are still convinced that we are all doomed.

    • AndyG55 permalink
      April 29, 2015 12:22 pm

      Looking just at Australia data, (I’m an Aussie, in case you hadn’t figured it out yet)

      There has been basically a ZERO warming since the beginning of 1998. (0.0014ºC/year

      In fact , if you take from 1979 to just before the small El Nino effect in 1998, there is basically a zero trend there as well. (0.009ºC/year)

      The ONLY real warming in the satellite data is the 1998 El Nino event.

      That step appears to be about 0.3ºC in the Australian data as well as in the global data.

      • AndyG55 permalink
        April 29, 2015 12:26 pm

        error correction..

        There has been basically a ZERO warming since the beginning of 1998.

        ( 0.0004ºC/year )

    • Howard permalink
      May 1, 2015 4:01 pm

      I am trying to renew and old contact with a personal friend. Are you Jacksel Broughton? Do you live in Santa Barbara? Are you a retired Air Force Col. Howard Lowe – Houston.

  5. April 29, 2015 10:34 am

    Of course this will get misreported by our MSM and BBC friends.
    I imagine as “the new version reduces the warming trend since 1979 from 0.140C to 0.114C/decade. what do you think ‘Tony’ about this report that shows that the temperature is rising faster than ever ?
    – Note how in 2014 interview with B Peiser the BBC local radio presenter mixed up Ozone hole and Climate Change.

    • April 29, 2015 4:20 pm

      According to my data set, earth has been warming at about 0.012K since 1974 (which corresponds closely now with Roy’s figures)
      It has been cooling at ca. -0.015K per annum since 2000.
      Ask Paul to publish my results.
      [it seems to me, I am always right?]

      • April 29, 2015 6:16 pm

        According to my data set, earth has been warming at about 0.012K since 1974 (which corresponds closely now with Roy’s figures)

        that should read

        According to my data set, earth has been warming at about 0.012K per annum since 1974 (which corresponds closely now with Roy’s figures)

      • AndyG55 permalink
        April 29, 2015 8:17 pm

        It has not been a trend warming.. It is a step warming from one event.

        I don’t know about your data, but this is very obvious in both UAH and RSS.

        Very little warming before, cooling since.

      • April 29, 2015 8:32 pm

        See my reply to norman. No steps in the speed of warming.
        All quadratic functions

      • AndyG55 permalink
        April 29, 2015 9:20 pm

        Have you stepped those years backward and forward to see if its robust?

        Please show the graph when you step all your picked years forward 2 years.

        Why not display all the trends for each year on your little parabolic graph?

        Sorry Henry, but there is no trend in the RSS or UAH data, just the step change due to the El Nino.

      • April 29, 2015 9:56 pm

        Andy says: Please show the graph when you step all your picked years forward 2 years.

        Henry says,
        that would be silly, as it [the speed of warming/cooling) is predictable from the equation, which stands true if it is 100% correlated with 4 points (as is the case with minima that I checked, 54 stations x 365days x 40years =788400 measurements, balanced 50/50% NH/SH, to almost zero by latitude and 70/30% @sea/inland )

        Anyway, for means I got 0.012K per annum since 1974 and Roy has 0.0114K/annum since 1978 so we are good. From the new milennium it started cooling:

        and this will continue until 2038.

      • AndyG55 permalink
        April 29, 2015 10:15 pm

        There was a very small, insignificant warming trend before the El Nino.

        It has been cooling since the culmination of that El Nino in 2001, at about the same magnitude as the prior small warming trend.
        That cooling has cancelled the small warming trend from before the El Nino.

        The only major warming in the whole satellite record was the El Nino step of approximately 0.3ºC.

        Only by including that step can you producing any warming trend what-so-ever.

      • AndyG55 permalink
        April 29, 2015 10:22 pm

        “that would be silly, as it [the speed of warming/cooling) is predictable from the equation, which stands true if it is 100% correlated with 4 points ”

        Seriously ?

        3 points will always lie on a parabola.. It only takes one lucky or specially selected point for the 4th point.

        Show us ALL the warming trends for each year,
        Show us how predictable the “equation” is.

    • April 29, 2015 4:44 pm

      Actually, ozone has something to do with natural climate change, but so do peroxides and nitrogenous oxides.
      There are only a few of us who figured it all out.

      • April 29, 2015 4:48 pm

        That last comment was meant @stewgreen.

      • nigel permalink
        May 1, 2015 12:27 pm

        A subtle point:

        Time is NEVER an EXPLANATORY variable.

        A time series which appears to be neither entirely RANDOM nor obviously PERIODIC, is properly first described as SYMPTOMATIC, not as TRENDING.

        For, one does not FIND trends in a time series, one IMPOSES them through a model (which is often implicit, but should be explicit) and then sees whether this indicates with reasonable probability that there is an explanatory variable, or variable process, masquerading as, or manifesting through, time.

        ‘Andyg55’ is suggesting an explanatory model for the ‘anomalies of temperature’ time series, which is along the lines of, “mean-reverting random” all the time, combined with a single step-change in the mean, caused by particular features of the 1998 El Nino.

        ‘MorecarbonOK’ is suggesting, by insisting on the word TREND for the whole period, an implicit model in which there really is an underlying small change every second in a warming direction, caused by something definite like increasing CO2, whilst everything else is perturbations with a mean of zero.

        There is a useful ‘rule of thumb’ in analyzing a time series which is that you do not think ‘Trend!’ between two periods, if the data for the two periods has overlap at well separated times. Since all the UAH and RSS temperature series have all of the data SINCE the 1990’s well inside the extremes of the late 1990’s and therefore overlapping with the data of the period of the late 1990’s, this suggests that the word is probably inappropriate for the last twenty years.

  6. April 29, 2015 5:57 pm

    It is of interest that the trends in the UAH v6 are much closer to the RSS data,. In particular they confirm the RSS global cooling trend since 2003 when the natural millennial solar activity cycle peaked.
    It is these satellite data sets which should be used in climate discussions because the land and sea based data sets have been altered and manipulated so much over the years in order to make them conform better with the model based CAGW agenda.
    The IPCC climate models are built without regard to the natural 60 and more importantly this 1000 year periodicity so obvious in the temperature record. This approach is simply a scientific disaster and lacks even average commonsense .It is exactly like taking the temperature trend from say Feb – July and projecting it ahead linearly for 20 years or so. The models are back tuned for less than 100 years when the relevant time scale is millennial. This is scientific malfeasance on a grand scale.
    The temperature projections of the IPCC – Met office models and all the impact studies which derive from them have no solid foundation in empirical science being derived from inherently useless and specifically structurally flawed models. They provide no basis for the discussion of future climate trends and represent an enormous waste of time and money. As a foundation for Governmental climate and energy policy their forecasts are already seen to be grossly in error and are therefore worse than useless.
    A new forecasting paradigm urgently needs to be adopted and publicized ahead of the Paris meeting.
    For forecasts of the timing and extent of the coming cooling based on the natural solar activity cycles – most importantly the millennial cycle – and using the neutron count and 10Be record as the most useful proxy for solar activity check my blog-post at
    The most important factor in climate forecasting is where earth is in regard to this quasi- millennial natural solar activity cycle which has a period in the 960 – 1020 year range. For evidence of this cycle see Figs 5-9. From Fig 9 it is obvious that the earth is just approaching ,just at or just past a peak in the millennial cycle. I suggest that more likely than not the general trends from 1000- 2000 seen in Fig 9 will likely repeat from 2000-3000 with the depths of the next LIA at about 2650. The best proxy for solar activity is the neutron monitor the count and 10 Be data. My view ,based on the Oulu neutron count – Fig 14 is that the solar activity millennial maximum peaked in Cycle 22 in about 1991. There is a varying lag between the change in the in solar activity and the change in the different temperature metrics. There is a 12 year delay between the neutron peak and the probable millennial cyclic temperature peak seen in the RSS data in 2003.
    There has been a declining temperature trend since then (Usually mis-interpreted as a “pause”) There is likely to be a steepening of the cooling trend in 2017- 2018 corresponding to the very important Ap index break below all recent base values in 2005-6. Fig 13. The Polar excursions of the last few winters are harbingers of even more extreme winters to come more frequently in the near future.

  7. April 30, 2015 2:20 am

    Thanks, Paul. This is good news!
    With UAH and RSS closely agreeing instead of going in different ways since 1979, there is no reason to rely on heavily adjusted and homogenized thermometers.

  8. ColA permalink
    April 30, 2015 5:41 am

    Will someone please show this information to the Pope he needs to pray for the BoM to do some urgent homogenisation!!! 🙂 🙂

  9. April 30, 2015 2:43 pm

    the sun is absolutely spotless….
    You share a very rare moment with me in history. The sun is now at its absolute brightest point in 87 or 88 years.
    I feel like I am pissing in my own (black) pants: it gives you a warm feeling but nobody notes it…..

  10. April 30, 2015 2:47 pm

    I am puzzled about the date, it should have been 30/04/2015
    I try again

  11. April 30, 2015 2:48 pm

    OK, well, it seems the picture is not saved every day, but it means the sun has been spotless now since at least 10 days ago.

  12. April 30, 2015 2:50 pm

    sorry if you are looking for a reference:

  13. April 30, 2015 7:20 pm

    I wonder if you guys also can feel that the sun is hotter? I cannot go outside here without my hat for 5 minutes or my ears get burned….
    here: is South Africa

  14. nigel permalink
    May 1, 2015 8:02 am

    The Royal Observatory of Belgium has a good sun site. They state that Cycle 24 peaked one year ago – but also that it hasn’t said its last word.

    • May 1, 2015 10:17 am

      thx, nigel


      “Therefore, cycle 24 proves to be 30% weaker than the previous solar cycle, which reached 119.7 in July 2000, and thus belongs to the category of moderate cycles, like cycles 12 to 15, which were the norm in the late 19th and early 20th century”.

      It is exactly like I said:
      2016 = 1927

      give or take a year.

  15. May 1, 2015 1:45 pm

    Good news for all weather- and climate realists…, bad news for all the “adjusters” and “alarmists”…

  16. May 1, 2015 3:10 pm

    nigel says
    MorecarbonOK’ is suggesting, by insisting on the word TREND for the whole period, an implicit model in which there really is an underlying small change every second in a warming direction, caused by something definite like increasing CO2, whilst everything else is perturbations with a mean of zero.

    henry says
    if the climate scientists looked at maxima (see graph above, established in 2012) and minima they would long have figured it out [that you must look at energy coming in and leaving]

    instead they insist on looking at means, which in itself is a bit of a labyrinth,
    e.g. my A-C wave for the drop in maximum temperatures obviously does not reflect exactly at the same time what happens to temperatures on earth. Earth has an intricate way of storing energy in the oceans. There is also earth’s own volcanic action, lunar interaction (mixing of warm and cooler waters), the turning of Earth’s inner iron core, electromagnetic force changes, etc.

    CO2 has absorption in energy leaving earth but it is very low level. Ozone, peroxides and nitrogenous oxides, which btw are manufactured by the sun usw TOA, have absorption in UV A + B, 200-300 nm which is coming in; the level of this energy is many, many times higher than the CO2 problem going outwards. Remember the solar spectrum has a chi-square distribution. Go figure.
    Ask me more.

  17. May 1, 2015 6:29 pm

    in the light of activity the current very low solar activity and all of my own results on temperature, i.e being able to identify the exact time period of the Gleissberg cycle,
    I am predicting that the solar fields will switch over again, within the next 12 months,
    in other words,

    the dotted lines will go in the opposite direction, not as predicted in this picture, but rather down to zero field strength and then switch over again, meaning we would have two switch overs within “one” solar cycle

    this phenomenon [when it happens] of the change of the solar dynamo appears to be caused by some gravitational force [by the planets]

    When the switch does occur, we will start the beginning of the new Gleissberg cycle.


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