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

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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About Bob Tisdale

Research interest: the long-term aftereffects of El Niño and La Nina events on global sea surface temperature and ocean heat content. Author of the ebook Who Turned on the Heat? and regular contributor at WattsUpWithThat.
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23 Responses to An Introduction To The Hadley Centre’s New HADSST3 Sea Surface Temperature Data

  1. kim says:

    You can’t make fudge without picking some smudge.
    ================

  2. Pingback: Anonymous

  3. Bob Tisdale says:

    Thanks, Pascvaks. It never occurs to me to add a link to the additional comments at WUWT. One of these days, I’ll have to add the links to all of my posts at WUWT.

  4. Julian Flood says:

    The new graph — is it just me or does it look like a series of 30 year trends? 1850 to 1880, rising, 1880 to 1910, falling, etc.

    Can that be simulated by something like a linear 1 dec C per century and a sine wave of amplitude about .4? If so then I suspect that those adjusting the data may have done us all a big favour. It could save trillions.

    JF

  5. timetochooseagain says:

    The corrections seem to have the effect of bringing the AMO as calculated by HADSST more closely in accord with the “Kaplan SST” variations:

    http://devoidofnulls.wordpress.com/2011/07/14/new-sst-record-effects-on-amo/

  6. Robert E. Phelan says:

    Bob:

    Sorry for the OT. I want to borrow one of your blink comparators but am having a devil of a time getting what I need. Could you send me an e-mail that I can respond to and I’ll explain what I want, why I want it, etc.

    Regards,
    Another Bob

  7. Bob Tisdale says:

    Robert E. Phelan: Whatcha need? Didn’t I include a direct tinypic link?

  8. Bob Tisdale says:

    timetochooseagain: The HADSST3 corrections certainly did bring their North Atlantic SST anomalies back into line with Kaplan. I never really noticed how much the 1940 hump and 1945 discontinuity impacted the HADSST2 AMO data. Thanks for the heads-up.

  9. nevket240 says:

    http://www.csiro.au/news/Ocean-salinities-show-an-intensified-water-cycle.html

    Bob. I do not know if you are aware of this work or the claims made.

    http://journals.ametsoc.org/doi/pdf/10.1175/2010JCLI3377.1

    this is the paper link.
    regards

  10. Bob Tisdale says:

    nevket240: Thanks for the link. I had not seen it yet.

  11. timetochooseagain says:

    nevket240-Aside from the tendency for “hydrological cycle acceleration” being conflated with all manner of doom and gloom notions about hydrological extremes, there is not much controversial about the idea, basically it says that, globally, there should be some increase in precipitation and evaporation from increased temperature…but that is true of a change regardless of the cause, and it is not clear how it is supposed to be a bad thing, unless one conflates it with other hydrological trends on a local to regional scale, which is wrong.

  12. Hi Bob,
    I followed your posts only occasionally via Antony´s website. But now you may help me to understand SST calculation better. I work since some time on a scientific paper looking for all the possible – mostly systematic- errors which are present in historical meteorological temperature as well as sea level data. Due to that measurement of SST and its potential errors as well as their possible compensation is one of the most interesting aspects of this work. The papers of Pat Frank recently published in E & E („Uncertainty in the global average surface air temperature index: representative lower limit“ and „Imposed and Neglected Uncertainty in the Global Average Surface Air Temperature Index“) show in some details also the direction of my work, although I go in specifiying the potential errors much deeper. Since oceans are covering about 70 % of earth surface and due to the fact that Hadley as well as CRU are using SST rather than MAT for their global calculation I am interested in the answers of the following questions.
    1. Where can I find evidence that SST can be used as a “..good surrogate for marine air temperature…” as Brohan 06 pointed out. I know Parker et. al 2004 as well as others Jones et al 1999 (p.174 and p 175) but found nothing at Parker but only a statement in Jones. Especially I wonder how problem is solved having air temperatures below -1.8 °C which are quite normal in higher latitidues north an south, bit seawater freeze to ice.
    2. What methods are used over time to construct daily means, monthly means, annually means of SST in order to determine its anomaly against the “station normal”. ( is this called climatology?). As far as I have learnt this is done by selecting a grid box and draw in this by hand or computer an isoline of same temperature but for 4 different times 0-6-12-18 o,clock. Than using the value of each time per day in oder to produce the gridded mean. Is this correct?
    3. How did they manage to produce an timeseries with an uncertainty of only ± 0.1 °C of global SST (Brohan 06) having seen Reynolds REYNOLDS, R. W. & RAYNER, 2002] p 1611 and Rayner 2002 (Improved Analyses of Changes and Uncertainties in Sea Surface Temperature Measured In Situ since the Mid-Nineteenth Century: The HadSST2 Dataset) FIG. 9. “Time series of global SST data availability for each month 1826–2004: (a) number of 5° area grid boxes containing data; (b) number of observations” … how sparse the data had been over time as well as over the area. I wondered how Hadley GISS and CRU can calculate a SST map for the whole oceans of the world by using this poor data.
    From my understanding as an engineer I am not able to understand how to produce such a small uncertainty knowing al lot about measurements errors. I am also well aware about used method of anomalies and its behaviour.
    Thanks for your help
    Michael

  13. Bob Tisdale says:

    Michael Limburg: Your questions are very detailed and beyond my ability to answer. Have you tried asking Richard Reynolds or any other of the NOAA scientists responsible for the SST data?
    Reynolds email address is at the bottom of the following link:

    http://www.emc.ncep.noaa.gov/research/cmb/sst_analysis/

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  21. tallbloke says:

    Hi Bob, why does HADsst3 only go to 2006 on the KNMI explorer?

  22. Bob Tisdale says:

    As far as I know, tallbloke, the Hadley Centre is splicing HADSST2 data onto it for Jan 2007 to present as a temporary measure until they figure out how to update HADSST3 in a timely manner.

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