GISS says CRU Better0001

Document Sample
GISS says CRU Better0001 Powered By Docstoc
					RE: USA temperatures - question from USA TODAY



              Subject: RE: USA temperatures - question from USA TODAY
              From: Reto Ruedy <rruedy@giss.nasa.gov>
            . Date: Wed, 29 Aug 2007 14:45:41 -0400
            To: "Rice, Doyle" <drice@usatoday.com> .
            CC: James Hansen <jhansen@giss.nasa.gov>, Makiko Sato <makis@giss.nasa.gov>, Reto Ruedy
            <cdrar@giss.nasa.gov>

             Doyle,

             Since this is a technical question        and Dr. aansen      is busy   this
             afternoon, I'll answer it:      .

             No, your statement is NOT correct; to get the US means, NCDC's procedure
             of only using the best stations is more accurate. If that were our goal,
             we would proceed in the same way. Actually, whenever we report on US
             means in our publications, we recompute all US means using only USHCN
             data.

             My recommendation to you is to continue using NCDC's data for the US
             means and Phil Jones' data for the global means. Our method is geared                 to
             getting the global mean and large regional means correctly enough to
             assess our model results.

             We are basically a modeling group and were forced into rudimentary
             analysis of global observed data in the 70's and early 80's since nobody
             else was doing that job at the time. Now we happily combine NCDC's and
             Hadley Center's data to get what we need to evaluate our model results.
             For that purpose, what we do is more than accurate enough. But we have
             no intention to compete with either of the other two organizations  in
             what they do best.

             Sincerely,

             Reto

             On Wed,    2007-08-29   at 12:36 -0400,   Rice,   Doyle    wrote:
              Jim

              Thank you for sending      this clarification.     I also received      the graphs
              from Makiko.



              So is it correct to say that NASA's data is more accurate than NCDC's
              since it has more sources?  In the media, it would be ideal to refer
              to one source rather than two. Traditionally we've used NCDC's data.



              And globally,    we usually   use the Hadley     Centre    data ...

              http://www.cru.uea.ac.uk/cru/info/warming/



              Doyle    Rice




1 nf ..:t                                                                                               12/17/2009 1:01 PM
te: USA temperatures - question from USA TODAY




         Subject: Re: USA temperatures - question from USA TODAY
         From: "James Hansen" <jhansen@giss.nasa.gov> .
         Date: Wed, 29 Aug 2007 16:12:20 -0400
         To: "Rice, Doyle" <drice@usatoday.com>
         cc: "Makiko Sato" <makis@giss.nasa.gov>, "Reto Ruedy" <cdrar@giss.nasa.gov>,           "James Hansen"
         <jhansen@giss.nasa.gov>

         Well, I guess that I would Say it a bit differently.

         Our method of analysis has features that are different than the analyses of the other groups. In some
         cases the differences have a substantial impact.

         For example, we extrapolate station measurements as much as 1200 km. This allows us to include
         results for the full Arctic. In 2005 this turned out to be important, as the Arctic had a large positive
         temperature anomaly. We thus found 2005 to be the warmest year in the record, while the British did
         not and initially NOAA also did not. Independent satellite IR measurements showed that our
         extrapolations of anomalies into the Arctic were conservative. I am very confident that our result was
         the correct one in that instance.

         Also, as we show in our 2001 paper, our urban warming correction in the U.S. differs from the NOAA
         correction (we have a larger adjustment, which decreases recent temperatures relative to last century). I
         would not claim that one is superior to the other, but the different results provide one conservative
         measure of uncertainty. In general it has proven very useful to have more than one group do the
         analysis.

         Also it should be noted that the different groups have cooperated in a very friendly way to try to
         understand different conclusions when they arise. You will see that we had co-authors from the other
         groups on our 2001 paper. And in general it is a bad idea to anoint any group as being THE authority.
         Science doesn't usually work best that way.

         Jim


         On 8/29/07, Reto Ruedy <rruedy@giss.nasa.gov>          wrote:
          Doyle,

           Since this is a technical question and Dr. Hansen is busy this
           afternoon, I'll answer it:

           No, your statement is NOT correct; to get the US means, NCDC's procedure
           of only using the best stations is more accurate. If that were our goal,
           we would proceed in the same way. Actually, whenever we report on US
           means in our publications, we recompute all US means using only USHCN
           data.

           My recommendation to you is to continue using NCDC's data for the US
           means and Phil Jones' data for the global means. Our method is geared to
           getting the global mean and large regional means correctly enough to
           assess our model results.


1 nf"                                                                                                      12/17/2009 1:02 PM
: USA temperatures - question from USA TODAY




         We are basically a modeling group and were forced into rudimentary
         analysis of global observed data in the 70's and early 80's since nobody
         else was doing that job at the time. Now we happily combine NCDC's and
         Hadley Center's data to get what we need to evaluate our model results.
         For that purpose, what we do is more than accurate enough. But we have
         no intention to compete with either of the other two organizations in
         what they do best.

         Sincerely,

         Reto

         On Wed, 2007-08-29 at 12:36 -0400, Rice, Doyle wrote:
         > Jim
         >
         > Thank you for sending this clarification. I also received the graphs
         > from Makiko.
         >
         >
         >
         > So is it correct to say that NASA's data is more accurate than NCDC's
         > since it has more sources? In the media, it would be ideal to refer
         > to one source rather than two. Traditionally we've used NCDC's data.
         >
         >
         >
         > And globally, we usually use the Hadley Centre data ...
         >
         > http://www.cru.uea.ac.uk/cru/info/warmingl
         >
         >
         >
         > Doyle Rice
         >
         >
         >
         >
         >
         >
         >
         >
         >
           ------------~------~~~----------~--------------------~-
         > From;"    @    .com [mailto: .fn\.
                                              com] On Behalf
                                        ~
         > Of James Hansen
         > Sent: Wednesday, August 29,20078:48 AM
         > To: rruedy@giss_nasa.gov
         > Cc: Rice, Doyle; Makiko Sato; James.E.Hansen@nasa.gov; Reto Ruedy
         > Subject: Re: USA temperatures - question from USA TODAY


                                                                                    12/1~/2009 1:02 PM

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:6005
posted:3/22/2010
language:English
pages:3