From	Michael E. Mann	Date	Thu, 16 Oct 2008 13:00:59 -0400
To	Phil Jones
CC	Judith Lean, Yousif K Kharaka
Subject	Re: Why are the temperature data from Hadley different from NASA?
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 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 ---------------------------------------------------------------------------- -- 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 Visible links 1. mailto:ykharaka@usgs.gov 2. mailto:jenkins@chartwood.com 3. mailto:allyson_anderson@energy.senate.gov 4. mailto:drahovzal@uky.edu 5. mailto:dvance@arcadis-us.com 6. mailto:ebarron@jsg.utexas.edu 7. mailto:eshinn@marine.usf.edu 8. mailto:jarmenrock@gmail.com 9. mailto:jblank@aapg.org 10. mailto:Jeffrey@LevineOnLine.com 11. mailto:jjones@vanoperating.com 12. mailto:julie.kupecz@shell.com 13. mailto:pgrew@unlnotes.unl.edu 14. mailto:rick-bsr@tyler.net 15. mailto:scott.tinker@beg.utexas.edu 16. mailto:tpaexpl@aol.com 17. mailto:w.a.morgan@conocophillips.com 18. Notes:///8825668F00670ABE/DABA975B9FB113EB852564B5001283EA/A93F684FF508B452872574D90044850F 19. mailto:ykharaka@usgs.gov 20. mailto:mann@psu.edu 21. http://www.meteo.psu.edu/~mann/Mann/index.html 22. http://www.essc.psu.edu/essc_web/news/DirePredictions/index.html 23. mailto:p.jones@uea.ac.uk 24. mailto:mann@psu.edu 25. http://www.meteo.psu.edu/~mann/Mann/index.html 26. http://www.essc.psu.edu/essc_web/news/DirePredictions/index.html Hidden links: 27. http://www.met.psu.edu/dept/faculty/mann.htm