NOAA and NASA "versions" of average US temperature

17 Jan 20120

I've already posted this graph somewhere else but I can't find it. So I'll start a new thread.

It shows that the 2009 annual US temperature, according to NOAA, returned to the 20th century average. That's a bit of a surprise, isn't it, what with all those hockeysticks we are so accustomed to seeing?

A bit of background.

There are three institutions that collate global temperature datasets, CRU, NOAA and NASA/GISS. They are all based on the Global Historical Climate Network that has been described in detail by the Chiefio here http://thesequal.proboards.com/index.cgi?board=climate&action=display&thread=20

The GHCN is deeply flawed. It was savagely reduced in about 1990 from 6,000 to about 1,500 surface stations, its raw data are subject to SERIOUS Urban Heat Island Effect and other non-climatic distortions and some of the data has already been fiddled with by the National Metorological Bureaux before it even gets o the GHCN!

THEN the IPCC favoured sons (NASA/GISS, NOAA and CRU) get to fiddle with it even more (adjustments and homogenisation) to produce their idea of what the global average temperature is. This thread is about the difference between the NASA/GISS and NOAA figures for the United States.




Steve McIntyre cautions:

Readers need to keep in mind that there is a substantial “divergence” between NOAA US and NASA US temperatures as shown in the graphic below. Since 1940, NOAA’s US has increased relative to NASA’s US at a rate of 0.39 deg C/century, thus 0.27 deg C since 1940.



Figure 2. Difference (deg C) between NOAA US and NASA US temperature anomalies.


At present, we don’t know very much about the NOAA calculation. To my knowledge, they make no effort to make a UHI adjustment along the lines of NASA GISS. As I’ve mentioned before, in my opinion, the moral of the surfacestations.org project http://www.surfacestations.org/ in the US is mainly that it gives a relatively objective means of deciding between these two discrepant series. As others have observed, the drift in the GISS results looks like it’s going to be relatively small compared to results from CRN1-2 stations – a result that has caused some cackling in the blogosphere. IMO, such cackling is misplaced.

The surfacestations results give an objective reason to view the the NOAA result as biased. It also confirms that adjustments for UHI are required. Outside the US, the GISS meta-data on population and rural-ness is so screwed up and obsolete that their UHI “adjustment” is essentially random and its effectiveness in the ROW is very doubtful. Neither NOAA nor CRU even bother with such adjustments as they rely on various hokey “proofs” that UHI changes over the 20th century do not “matter”.

Steve then tetchily points out that though we layfolk may be surprised that there should be a difference between the findings of NOAA and NASA that is based on a wrong assumption. He says "you’re assuming that there is “data” that gives you a straightforward answer; there isn’t. Measurement systems and environments have changed. Having said that, there are better and worse data sets and better and worse ways of handling data. There are dozens of threads on this."

So, we've been told!

It take it that this means until the data are settled the science is not settled, either. Good! Glad we've got that sorted.

I found the original graph which I obtained from Pat Michaels' blog entitled

"Another normal year in the US"

http://www.worldclimatereport.com/index.....year-in-the-us/








Figure 1. U.S. annual average temperature, 1895-2009 (source: National Climatic Data Center)