From: Michael Mann <mann@meteo.psu.edu>
To: Phil Jones <p.jones@uea.ac.uk>
Subject: Re: Why are the temperature data from Hadley different from NASA?
Date: Thu, 16 Oct 2008 13:00:59 -0400
Cc: Judith Lean <jlean@ssd5.nrl.navy.mil>, Yousif K Kharaka <ykharaka@usgs.gov>

   thanks Phil--this all makes sense. I'll be intrigued to hear more about how the melting sea
   ice issue is going to be dealt with. no question there is a lot of warming going on up
   there.

   hope to see you one of these days,

   mike

   On Oct 16, 2008, at 6:52 AM, Phil Jones wrote:

    Hi Mike, Judith and Yousif,
       Mike has basically answered the question. The GISS group average surface T data into
    80 equal area boxes across the world. The UK group (CRU/MOHC) grid the data into
    5 by 5 degree lat/long boxes, as does NCDC. These griddings don't allow so much
    extrapolation of data - no extrapolation beyond the small grid box. The US groups also
    calculate the globe as one domain, whereas we in the UK use (NH+SH)/2.  This also
    makes some difference as most of the missing areas are in the SH, and currently the NH
    is warmer than the SH with respect to 1961-90. Our rationale for doing what we do is that
    it is better to estimate the missing areas of the SH (which we do by tacitly assuming they
    are the average of the rest of the SH) from the rest of the SH as opposed to the rest of
    the world.
        The Arctic is a problem now. With less sea ice, we are getting SST data in for regions
    for which we have no 1961-90 averages - because it used to sea ice (so had no
   measurements).
    We are not using any of the SST from the central Arctic in summer.
    So we are probably underestimating temperatures in the recent few years. We're working
    on what we can do about this. There are also more general SST issues in recent years.
    In 1990, for example, almost all SST values came from ships. By 2000 there were about
    20% from Buoys and Drifters, but by 2008 this percentage is about 85%. We're also
    doing comparisons of the drifters with the ships where both are plentiful, as it is
    likely that drifters measure a tenth of one degree C cooler than ships, and the 1961-90
    period is ship-based average.
        New version of the dataset coming in summer 2009.
      All the skeptics look at the land data to explain differences between datasets and
    say urbanization is responsible for some or all of the warming. The real problem is
    the marine data at the moment.
      Attaching a recent paper on urbanization and effects in China.
    Cheers
    Phil
   At 22:08 15/10/2008, Michael Mann wrote:

     Hi Judith,
     Its nice to hear from you, been too long (several years??).  My understanding is that
     the differences arise largely from how missing data are dealt with.  For example, in Jim
     et al's  record the sparse available arctic data are interpolated over large regions,
     whereas Phil an co. either use the available samples or in other versions (e.g. Brohan
     et al) use optimal interpolation techniques. The bottom line is that Hansen et al 'j05 I
     believe weights the high-latitude warming quite a bit more, which is why he gets a
     warmer '05, while Phil and co find '98 to be warmer.
     But Phil can certainly provide a more informed and complete answer!
     mike
     p.s. see you at AGU this year??
     On Oct 15, 2008, at 5:03 PM, Judith Lean wrote:

     Hi Yousif,
     Many apologies for not replying sooner to your email - but I've only just returned from
     travel and am still catching up with email.
     Unfortunately, I am simply a "user" of the surface temperature data record and not an
     expert at all, so cannot help you understand the specific issues of the analysis of the
     various stations that produce the differences that you identify. I too would like to
     know the reason for the differences.
     Fortunately, there are experts who can tell us, and I am copying this email to Mike Mann
     and Phil Jones who are such experts.
     Mike and Phil (hi! hope you are both well!), can you please, please help us to
     understand these differences that Yousif points out in the GISS and Hadley Center
     surface temperature records (see two attached articles).
     Many thanks, for even a brief answer, or some reference.
     Judith
     On Oct 8, 2008, at 1:50 PM, Yousif K Kharaka wrote:

     Judith:
     I hope you are doing well (these days OK would be good!) at work and personally.
     Can you help me to understand the huge discrepancy (see below) between the temperature
     data from the Hadley Center and GISS? Any simple explanations, or references that I can
     read on this topic? I certainly would appreciate your help on this.
     Best regards. Yousif Kharaka
     Yousif Kharaka, Research Geochemist      Phone: (650) 329-4535
     U. S. Geological Survey, MS 427                   Fax: (650) 329-4538
     345, Middlefield Road                                       Mail: [1]ykharaka@usgs.gov
     Menlo Park, California 94025, USA
     ----- Forwarded by Yousif K Kharaka/WRD/USGS/DOI on 10/08/2008 10:42 AM -----
     Yousif K Kharaka/WRD/USGS/DOI
     10/06/2008 02:07 PM

                                                                                            To

     "Dr David Jenkins" <[2]jenkins@chartwood.com >

                                                                                            cc

     [3]allyson_anderson@energy.senate.gov, [4]drahovzal@uky.edu, [5]dvance@arcadis-us.com,
     [6]ebarron@jsg.utexas.edu, "'Gene Shinn'" <[7]eshinn@marine.usf.edu>,
     [8]jarmenrock@gmail.com, [9]jblank@aapg.org, [10]Jeffrey@LevineOnLine.com,
     [11]jjones@vanoperating.com, [12]julie.kupecz@shell.com, [13]pgrew@unlnotes.unl.edu,
     [14]rick-bsr@tyler.net, [15]scott.tinker@beg.utexas.edu, [16]tpaexpl@aol.com,
     [17]w.a.morgan@conocophillips.com

                                                                                       Subject

     Why are the temperature data from Hadley different from NASA? [18]Link
     David and all:
     One advantage (or great disadvantage if you are very busy!) of membership in GCCC is
     that you are forced to investigate topics outside your areas of expertise. For some time
     now, I have been puzzled as to why global temperature data from the British Hadley
     Centre are different from those reported by NASA GISS, especially in the last 10 years.
     GISS reports that 2005 was the warmest year (see first attachment) on record, and that
     2007 tied 1998 for the second place. The Hadley group continues reporting 1998 (a strong
     El Nino year) as having the highest global temperature, and then showing temperature
     decreases thereafter. The two groups report their temperatures relative to different
     time intervals (1951-1980 for GISS; 1961-1990 for Hadley), but much more important is
     the fact that GISS data include temperatures from the heating Arctic that are excluded
     by others (see second attachment).  If you are interested in the topic of sun spots, the
     11-year irradiance cycle, and solar forcing versus AGHGs, see the first attachment for
     what NASA has to say.
     We may need help on this complex topic from a "true climate scientists", such as Judith
     Lean!
     Cheers. Yousif Kharaka
     Yousif Kharaka, Research Geochemist      Phone: (650) 329-4535
     U. S. Geological Survey, MS 427                   Fax: (650) 329-4538
     345, Middlefield Road                                       Mail: [19]ykharaka@usgs.gov
     Menlo Park, California 94025, USA

     <GCC-Data @ NASA GISS_ GISS Surface Temperature Analysis_ 2007.pdf>
     <GCC-2005 Warmest Year In A Century.pdf>

     <GCC-Data @ NASA GISS_ GISS Surface Temperature Analysis_ 2007.pdf><GCC-2005 Warmest
     Year In A Century.pdf>

     --
     Michael E. Mann
     Associate Professor
     Director, Earth System Science Center (ESSC)
     Department of Meteorology              Phone: (814) 863-4075
     503 Walker Building                    FAX:   (814) 865-3663
     The Pennsylvania State University      email:  [20]mann@psu.edu
     University Park, PA 16802-5013
     website: [21]http://www.meteo.psu.edu/~mann/Mann/index.html
     "Dire Predictions" book site:
     [22]http://www.essc.psu.edu/essc_web/news/DirePredictions/index.html

   Prof. Phil Jones
   Climatic Research Unit        Telephone +44 (0) 1603 592090
   School of Environmental Sciences    Fax +44 (0) 1603 507784
   University of East Anglia
   Norwich                          Email    [23]p.jones@uea.ac.uk
   NR4 7TJ
   UK
   ----------------------------------------------------------------------------

     <jonesetal2008_china.pdf>

   --
   Michael E. Mann
   Associate Professor
   Director, Earth System Science Center (ESSC)
   Department of Meteorology              Phone: (814) 863-4075
   503 Walker Building                    FAX:   (814) 865-3663
   The Pennsylvania State University      email:  [24]mann@psu.edu
   University Park, PA 16802-5013
   website: [25]http://www.meteo.psu.edu/~mann/Mann/index.html
   "Dire Predictions" book site:
   [26]http://www.essc.psu.edu/essc_web/news/DirePredictions/index.html

References

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   6. mailto:ebarron@jsg.utexas.edu
   7. mailto:eshinn@marine.usf.edu
   8. mailto:jarmenrock@gmail.com
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  13. mailto:pgrew@unlnotes.unl.edu
  14. mailto:rick-bsr@tyler.net
  15. mailto:scott.tinker@beg.utexas.edu
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  19. mailto:ykharaka@usgs.gov
  20. mailto:mann@psu.edu
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  22. http://www.essc.psu.edu/essc_web/news/DirePredictions/index.html
  23. mailto:p.jones@uea.ac.uk
  24. mailto:mann@psu.edu
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