Tisdale: An Introduction To The Hadley Centre’s New HADSST3 Sea Surface Temperature Data

 by Bob Tisdale

The Royal Netherlands Meteorological Institute (KNMI) has added the Hadley Centre’s new Sea Surface Temperature (SST) dataset HADSST3 to their Climate Explorer. (Thanks to Dr. Geert Jan van Oldenborgh for the update.) The following post is a quick introduction to the revisions to their global SST data. We’ll take a look at the individual ocean basins in a future post.

The new dataset was introduced in a two-part Kennedy et al (2011) paper:

Reassessing biases and other uncertainties in sea-surface temperature observations measured in situ since 1850, part 1: measurement and sampling uncertainties

And:

Reassessing biases and other uncertainties in sea-surface temperature observations measured in situ since 1850, part 2: biases and homogenisation

Note: The HADSST3 data ends in December 2006. Hopefully the Hadley Centre will be able to update the data in the near future.

Figure 1 is a time-series graph that compares the new HADSST3 Global SST data to its predecessor HADSST2. The data have been smoothed with 13-month running-average filters to reduce the noise and the seasonal signal. The largest correction occurs in 1945 to account for the discontinuity presented in the Thomson et al (2008) paper Identifying Signatures of Natural Climate Variability in Time Series of Global-Mean Surface Temperature: Methodology and Insights.

Figure 1

 

By subtracting the Global HADSST2 data from the HADSST3 data, Figure 2, the magnitude of the correction at that time becomes apparent. The Hadley Centre appears also to have increased the response to the 1883 eruption of Krakatoa, and reduced the rise from 1920 to 1940.

Figure 2

The long-term linear trends of the Global HADSST3 data are basically the same as HADSST2 at about 0.335 deg C per Century, as shown in Figure 3.

Figure 3

Let’s take a look at the trends during the two 20thCentury (plus) warming epochs and the mid-century cooling period. From January 1975 to December 2006, Figure 4, the global HADSST2 and HADSST3 linear trends are basically the same at 0.16 deg C per decade.

Figure 4

The corrections made to the early warming period, Figure 5, has reduced the linear trend for the period of January 1910 to December 1941 from 0.165 deg C per decade for the global HADSST2 data to 0.137 deg C per decade for the HADSST3 data.

Figure 5

The biggest change, of course, occurs during the mid 20thCentury cooling period. Figure 6 illustrates the Global SST anomalies for the two HADSST datasets for the period of January 1941 to December 1975. By correcting the discontinuity in 1945 and gradually aligning the data again in the early 1970s, the linear trend has dropped drastically from -0.008 deg C per decade for HADSST2 to -0.033 deg C per decade for the global HADSST3 data.

Figure 6

And that’s the period the IPCC models have difficulty reproducing. Figure 7 is a comparison of the global HADSST3 data to the IPCC Multi-Model Mean (20C3M) for the mid-century cooling era.

Figure 7

SOURCE

The IPCC Multi-Model Mean TOS data and the data for the two Hadley Centre SST datasets are available through the KNMI Climate Explorer:

http://climexp.knmi.nl/selectfield_obs.cgi?someone@somewhere

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31 thoughts on “Tisdale: An Introduction To The Hadley Centre’s New HADSST3 Sea Surface Temperature Data

  1. The 0.13 or 0.14 per decade increase is what I also get.
    However, what we also need to know is the increases in minima and maxima.
    Average global temp. increase does not show what it caused.
    According to my analysis (which is still on-going), the ratio of increase in
    maximum temps – average temps – and minimum temps
    6:2:1

    http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming

    Clearly it was maximum temps (that happen during the day) pushing up average temps.
    So that leads me to the conclusion that the warming was natural. There is nothing we can do, except be happy. For as long as it lasts.

  2. The Bear really does wish that all who go to so much obvious trouble to compose these `posts’ could go the extra step and draft a simple paragraph explaining in simple language what the implications of the post.

    Can someone help, with this one?

    Is it actually saying that, looked at over the appropriate time frame, the line of best fit shows a decrease in ocean temps, as opposed to an IPCCC claime increase?

  3. Bigred is another words-rather-than-numbers person who needs a simple paragraph explaining all this in simple language.

    Ta…

  4. Bob.
    Thank you for your efforts.

    http://www.bom.gov.au/climate/enso/enlist/index.shtml

    I wonder if you use this page at the BOM. My point in using it is to compare their ranking of various E-N events to the graphs you present. If the readers select different time periods they will find that the rankings pretty much tally with you graphical presentation. And the commentary is in some instances, telling. I’m referring to fig. 2 and the step changes.
    regards

  5. The corrections made to the early warming period, Figure 5, has reduced the linear trend for the period of January 1910 to December 1941 from 0.165 deg C per decade for the global HADSST2 data to 0.137 deg C per decade for the HADSST3 data.

    As revealed in the (in)famous Feb 2010 Q&A with Professor Phil Jones, 1910-1940 was one of the 4 periods with similar warming rates and “…not statistically significantly different from each other.”

    Period_____Length__Trend(°C/decade)__Significance
    1860-1880__21______0.163_____________Yes
    1910-1940__31______0.15______________Yes
    1975-1998__24______0.166_____________Yes
    1975-2009__35______0.161_____________Yes

    With these “corrections” is 1910-1940 no longer similar, so they may immediately begin the pronouncements about the late-20th century warming being “absolutely unprecedented” for the 20th century?

  6. HenryP says: “The 0.13 or 0.14 per decade increase is what I also get.
    However, what we also need to know is the increases in minima and maxima.”

    HADSST2, HADSST3, and Kaplan SST are provided as anomalies, not in absolute form. If you need absolute SST data, there’s always ERSST.v3b and HADISST and the satellite-era Reynolds OI.v2.

  7. Ref – TBear

    Judgment withheld. Significance unknown. Time will tell.

    PS: At a glance, looks like it may be an improvement over HADSST2.

  8. TBear (Warm Cave in Cold-as-Snow-Sydney)says….

    “Is it actually saying that, looked at over the appropriate time frame, the line of best fit shows a decrease in ocean temps, as opposed to an IPCCC claime increase?”

    A NOAA scientist has stated the oceans temperatures have decreased- but the heat content has increased because the oceans have increased in volume. This stand to reason if you think of the latent heat required to transform ice to water.

    However, all these figures a merely “estimates”.There is no real science in determining Global Temperatures prior to 1970. The UEA,CRU temperatures , particularly SSTs prior to then are not global and those they do rely on – SSTs- have been fiddled around with.

  9. TBear (Warm Cave in Cold-as-Snow-Sydney) says: “Is it actually saying that, looked at over the appropriate time frame, the line of best fit shows a decrease in ocean temps, as opposed to an IPCCC claime increase?”

    The IPCC isn’t claiming that the Sea Surface Temperatures increased during that mid-20th Century cooling period. What I’ve shown is that the IPCC’s multi-model mean of their 20C3M Hindcasts do not reproduce that cooling period. Then again, they don’t model the early warming period very well either:

    We can also illustrate how poorly the model mean captures the multidecadal variability of the SST data by looking at the difference between the observations and the model mean—that is, by subtracting the model mean from the SST data:

  10. @Laurie Ridyard: If ocean temperatures have decreased by spreading the increased heat content over a bigger volume, how does that work in tandem with the (pre-fudge) drop in sea levels? One would imagine that a temperature decrease simply reduced the volume and thus lowered the level?

  11. Sorry Bob, I am stupid. I see now that you are looking at the temp. changes on the seas,
    whereas I look on these land.
    Well, at least it is interesting to note that there is a bit of correlation….

  12. kadaka (KD Knoebel) says: “With these ‘corrections’ is 1910-1940 no longer similar, so they may immediately begin the pronouncements about the late-20th century warming being ‘absolutely unprecedented’ for the 20th century?”

    I’m glad someone caught that. Thanks. Now I have another graph to present that I prepared for the post, but did not include. The HADSST3 trend for the late warming period is 16% higher than the early 20th Century warming period trend(0.16 deg C per decade divided by 0.137 deg C per decade). Refer to Figures 4 and 5. But the IPCC multi-model mean for SST has the trend of the late warming period 3.6 times higher than the trend of the early period (0.126 deg C per decade divided by 0.035 deg C per decade):

    As usual, the models show no skill at reproducing the instrument temperature record. Kind of hard for anyone to attribute the recent warming to greenhouse gases when the models have no basis in reality.

  13. nevket240 says: “I wonder if you use this page at the BOM.”

    Thanks for the link. I know of the BOM’s discussions but I do not tyoically refer to them with my posts.

  14. Pascvaks says:
    quote
    PS: At a glance, looks like it may be an improvement over HADSST2.
    unquote

    I always look at the period 1940 to ’45. They have been trying to get rid of that blip since Tom Wigley wrote ‘why the blip?’. So, no, I don’t see it as an improvement, I see it as a continuation of their bad habits. Data should be explained, understood, not adjusted to fit the narrative.

    JF

  15. HenryP says: “Well, at least it is interesting to note that there is a bit of correlation….”

    There are a number of papers that describe why Land Surface Temperatures mimic Sea Surface Temperatures.

  16. The Bear suggests that Mr Watts might consider tagging esoteric posts, such as this one, as `technical’? Unless, or course, someone `in the know’ can draft a short summary of the significance of the information. Just a broad clue, would be nice.

    Do not take this as a general criticism of the site.

    The Bear loves this site and the information it provides.

    Focking cold, here in Sydney …. Grrrrrrr

  17. It looks like they are changing the temperature record to fit the models…

    Now that is some good science right there. (Micheal Mann with a redneck accent….) /sarc

  18. Robert M says: “It looks like they are changing the temperature record to fit the models… ”

    In this case they changed the temperature record and it will be more difficult for the models to replicate it.

  19. This kind of bugs me. I haven’t yet read the papers – but do I understand that because of the difficulty of matching the models to the data – they have used said models to CHANGE the data?

    The big changes for Krakatoa and 1920-1940 seem fishy to me. This is something that I must read to understand. Thanks for the analysis Bob! Great job. And thanks to KNMI.

  20. TBear (Warm Cave in Cold-as-Snow-Sydney) says:
    July 12, 2011 at 7:56 am

    Focking cold, here in Sydney …. Grrrrrrr

    20 centigrade! thats our summer temperature in the UK.

  21. Re Bob Tisdale on July 12, 2011 at 4:51 am:

    Well, it’s nice to know the models are even more screwed up than I thought. However it’s long been a contention among skeptics that those two earlier periods were similar in the rates of warming without the CO2 concentrations being as high as in the late 20th century, the period often cited as “unprecedented” in the rate of rise. I’m concerned that the 1910-1940 “adjustments” erase the similarity of that period. Further, I’ve also noticed according to your Figure 2 that they’ve made similar downward “adjustments” to the 1860-1880 period.

    They’ve admitted, as you’ve noted, that the models aren’t matching the instrumental record. So that’s moot. What skeptics have been arguing is from the instrumental record, how those two earlier periods had similar rates of warming. And now, in a manner I consider suspicious, these “adjustments” seem to have conveniently removed that argument.

  22. As someone who has followed this since reading about in the ClimateGate emails, I’m a little relieved they didn’t make more change than this – such as increasing the overall trend which it seems they did not do.

    But how are they going to keep it updated if ICoads is not going to be updated anymore?

    I guess they just append OIsst V2 to it but I note HadSST3 increases by about 0.1C more than OIsst V2 from November 1981 to December 2006 so they are not consistent.

  23. In numbered bullets, the comparison between the datasets reveals the following:

    1. The long-term (i.e., 150 years) warming trend remains essentially unchanged around 0.335 deg C per century.
    2. The second, short-term (i.e., 1975 to 2006) warming trend of the century remains essentially unchanged. This is the genesis of the global warming scare (promoted in its infancy by Hansen)
    3. The mid-century (i.e., 1941 to 1975) cooling trend is more pronounced (i.e., it cooled more than previously reported). This was the genesis of the global cooling scare (supported by a younger Hansen).
    4. The first, short-term (i.e., 1910 to 1945) warming trend of the century was less intense than previously reported.

    From an IPCC perspective, break out the bubbly for they will be happy with Bullets 1, 2, and 4. In fact, the claim will be made that the new dataset supports the existing models’ predictive abilities at trending – even in light of the limitations with the old dataset. Yes, the earth is warming, but I don’t think anyone (alarmist or skeptic) is denying or surprised with that.

    The IPCC will likely dismiss the significance of the cooling trend’s revision because the models mostly reference baselines that incorporate a portion of the trend. However, this doesn’t change the fact that the models (when run regressively) fail to report with any confidence this cooling trend. This failure casts doubt on the models’ abilities to track future trends (at least in the short-term and possibly long-term) with confidence. In fact, this has been confirmed by most of the existing models’ inability to track the current short-term cooling trend.

  24. I also like simple, plain, expalantions of what all this stuff actually means.

    In this case, the message seems to be

    (a) the models don’t fit the figures, so the models are crap
    (b) the figures are pretty much crap, too
    (c) no-one knows what the hell is going on
    (d) it’s damned cold in Brisbane, too
    (e) we’re doomed

    Did I miss anything?

  25. mrdarcy_pemberley says: “From an IPCC perspective, break out the bubbly for they will be happy with Bullets 1, 2, and 4.”

    They should not be happy with 4. The models show no skill at hindcasting the rise in SST anomalies during the early warming period.

    For the early warming period, the global SST trend for the multi-model mean is 0.035 deg C per decade while the observations show the rise was 0.137 deg C per decade.

  26. Bob Tisdale says: “They should not be happy with 4. The models show no skill at hindcasting the rise in SST anomalies during the early warming period.”

    As my spouse often qualifies my responses using the term, “should” is the operative word in that statement. Personally, I agree the discrepancy between the datasets for the first, short-term warming period in the last century casts further doubt on the models’ abilities. However, the difference is such that it’ll be lost in the scientific “chaff” that the AGW proponents would throw at the comparison of the datasets. “After all, the long-term trend is reaffirmed by both datasets, right?”

    This is overly simple but easily saleable to the global public.

    If pressed, though, the IPCC will likely (1) emphasize the “smallness” of the difference (statistical significance is immaterial when the planet’s fate is at stake), (2) attribute the discrepancy to the vagaries in the recording of the data (there’s always a range of error associated with human-initiated input, which must be tolerated), (3) and the more trustworthy data (because it incorporates these things called… satellites) is entirely affirmed, as reflected in the second, short-term warming trend.

    While we know it would be affirmed regardless given the baseline, that nuance is lost on the global public.

    So, on the whole, I believe the IPCC is “happy” with Bullet 4 because its supports the “storytelling” they enjoy vis-à-vis their summaries for policymakers.

  27. sceptical said on July 13, 2011 at 9:46 pm:

    So the planet is warming.

    Yup, in general, since the Little Ice Age, as we’ve been saying. Glad to know you’ve been paying attention. ☺

  28. whilst talking about the planet warming….

    I think I have pretty much eliminated the probability / possibility that the warming – or even part of the warming – is due to an increase in carbon dioxide or other GHG’s.

    http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming

    not so?
    However, when arguing with myself on this, I think we cannot get past the reasoning that all those planes,rockets, traffic, electricity and fuel (including nuclear) that we burn and use must be adding some warmth to atmosphere.

    the real problem is to find some kind of formula that would calculate the part of the warming that is man made.
    I think it simply has to be based on the total energy consumed versus the atual energy coming in from the sun, no matter how small that portion that may be?

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