RE: USA temperatures - question from USA TODAY
Subject: RE: USA temperatures - question from USA TODAY
From: Reto Ruedy
. Date: Wed, 29 Aug 2007 14:45:41 -0400
To: "Rice, Doyle" .
CC: James Hansen , Makiko Sato , Reto Ruedy
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" .
Date: Wed, 29 Aug 2007 16:12:20 -0400
To: "Rice, Doyle"
cc: "Makiko Sato" , "Reto Ruedy" , "James Hansen"
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 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