Watts Up With That?

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From environmentalist Jennifer Marohasy’s blog in Australia, please pay her a visit here – Anthony

There has been criticism of the potential for official weather stations in the USA to record artificially high temperatures because of the changing environments in which they exist, for example, new asphalt, new building or new air conditioning outlets.   Meteorologist, Anthony Watts, has documented evidence of the problem and Canadian academic, Ross McKitrick, has attempted to calculate just how artificially elevated temperatures might be as a consequence.

A reader of this blog, Michael Hammer, recently studied the official data from the US official weather stations and in particular how it is adjusted after it has been collected.   Mr Hammer concludes that the temperature rise profile claimed by the US government is largely if not entirely an artefact of the adjustments applied after the raw data is collected from the weather stations.

Does the US Temperature Record Support Global Warming?
By Michael Hammer

IN the US, the National Oceanic and Atmospheric Administration (NOAA) collects, analyses and publishes temperature data for the United States.   As part of the analysis process, NOAA applies several adjustments to the raw data.

If we consider, the above graph, which shows, their plot of the raw data  (dark pink) and the adjusted data (pale pink), it is obvious that the adjustments have little impact on data from early in the 20th century but adjust later temperature readings upwards by an increasing amount.  This means that the adjustments will create an apparent warming trend over the 20th century.  [Click on the above chart for a better larger view, this chart can also be viewed at http://cdiac.ornl.gov/epubs/ndp/ushcn/ndp019.html .]

NOAA state that they adjust the raw data for five factors.  The magnitude of the adjustments are shown in Figure 2.

Figure 2.  Form of individual corrections applied by NOAA. The black line is the adjustment for time of observation.  The red line is for a change in maximum/minimum thermometers used.  The yellow line is for changes in station siting. The pale blue line is for filling in missing data from individual station records. The purple line is for UHI effects (this correction is now removed).  [Click on the chart for a better larger view or visit the same website as for Figure 1.] Read the rest of this entry »