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Temperature Adjustments by National and Global Data Centers

By Joe D'Aleo
Monday, December 14, 2009

NOAA’s United States Historical Climate Network, USHCN was first established in 1990. First version had a UHI adjustment based on the work of Karl (who used the work of Oke and Landsberg among others). But lack of warming since 1940 was an inconvenient fact they had to explain away with US being a special case and only 19% of the global data.


That didn't sit well with some folks so in 1999, NCDC began a slow backing off of the surface UHI and in 2007, eliminated the urban heat island with the results below. These are NASA GISS plots of the USHCN network. Fortunately thanks to the late John Daly we have the earlier version from 1999 as plotted by NASA GISS to compare with. They have the current version as well. Note the significant changes made with cooling of the earlier 20th century warm period and a warming of the late 20th century ocean and solar driven cyclical peak.

The difference between the annual 1999 versus the current is shown below.

The data stations also suffer from increasingly bad siting as shown by Anthony Watts


It was at one time at least briefly the best of the global data bases.


The back off of UHI was very evident in Central Park data.

This is monthly for January - raw from NWS WSFO and UHI adjusted USHCN.

This would imply a depopulation of NYC post 1990. This is clearly not the case.

Had they left UHI constant, this would have been the result. Why no UHI shown in a big city? Because it has been a big city for the whole century and because the sensors are reasonably well sited in a park setting (as opposed to the old Battery Park site on the 23rd floor of the Whitehall Building on asphalt, next to the rivers (three sides) and southwest of a steampipe.

Here by the way is a plot of Central Park with USHCNV1 (rose), raw (blue) and the NOAA GHCN global (green) versions. In this case July (January very similar).

Note GHCN decided NYC raw data was not warm enough and adjusted upward. If NOAA can't decide what the right temperature for a well established and stable site should be to within 10F, how can we take their word on changes the order of a few tenths of a degree?????


Alaska Climate – Station Data vs Adjusted GHCN/IPCC

Dr. Richard Keen, University of Colorado wrote us to comment:

I recently completed a study of central Alaska's climate. For this study I computed the average annual temperature for nine long-term Alaskan stations (and station combinations), which are: Eagle/Dawson, Ft. Yukon/Central, Fairbanks University, McKinley Park, Talkeetna, Gulkana/Kennecott/Chitina/McCarthy, Yakutat, Cordova, and Valdez.  Then I averaged the nine stations for a regional mean.  The data source was NCDC.


The annual values on the next plot clearly show the dominance of the PDO in Alaskan climate. 

For comparison with the IPCC thumbnail for Alaska (I hope you can find an enlarged version of this), I replotted the regional temperatures as ten-year averages.  My averages show that the past three decades have shown no warming (since the PDO shift in 1977), and are in fact no warmer than the 1935-1944 decade.  This is very different from the IPCC which shows a substantial warming over the past three decades.

Here is the plot of annual versus the stages of the PDO, note the stepladder dscontinuities with the PDO climate shifts.

Here is the GHCN annual temperatures for the same region.  The GHCN data is dominated by an upward trend.  My analysis gives an upward linear trend of 0.69 C/century (due to starting during a cold PDO and ending during a warm PDO), while the GHCN trend is 2.83 C/century - over 2 degrees larger!

My study and the GHCN use the same stations, because there are no other long-term stations in the regions.  I applied no "corrections" beyond offsets used when combining two or more stations with overlapping records (no other adjustments were warranted).  One can only guess what "corrections" were applied to the GHCN and IPCC data sets, but I can easily guess their magnitude - about 1 degree.  Curiously, the magnitude of the adjustments is about the same as the "global warming" signal of the past century.

New Zealand – Are We Feeling Warmer Yet?

The Climate Conversation Group and the New Zealand Climate Science Coalition chimed in:


There have been strident claims that New Zealand is warming. The Inter-governmental Panel on Climate Change (IPCC), among other organizations and scientists, allege that, along with the rest of the world, we have been heating up for over 100 years.


But now, a simple check of publicly-available information proves these claims wrong. In fact, New Zealand’s temperature has been remarkably stable for a century and a half.

So what’s going on?


New Zealand’s National Institute of Water & Atmospheric Research (NIWA) is responsible for New Zealand’s National Climate Database. This database, available online, holds all New Zealand’s climate data, including temperature readings, since the 1850s. Anybody can go and get the data for free. That’s what we did, and we made our own graph. Before we see that, let’s look at the official temperature record. This is NIWA’s graph of temperatures covering the last 156 years: From NIWA’s web site –

Mean annual temperature over New Zealand, from 1853 to 2008 inclusive, based on between 2 (from 1853) and 7 (from 1908) long-term station records. The blue and red bars show annual differences from the 1971 - 2000 average, the solid black line is a smoothed time series, and the dotted [straight] line is the linear trend over 1909 to 2008 (0.92C/100 years).

This graph is the centrepiece of NIWA’s temperature claims. It contributes to global temperature statistics and the IPCC reports. It is partly why our government is insisting on introducing an ETS scheme and participating in the climate conference in Copenhagen. But it’s an illusion.

Dr Jim Salinger (who no longer works for NIWA) started this graph in the 1980s when he was at CRU (Climate Research Unit at the University of East Anglia, UK) and it has been updated with the most recent data. It’s published on NIWA’s website and in their climate-related publications.

The actual thermometer readings:

To get the original New Zealand temperature readings, you register on NIWA’s web site, download what you want and make your own graph. We did that, but the result looked nothing like the official graph. Instead, we were surprised to get this:

The seven stations Dr Salinger used to create the graph are (with start dates):

·  Auckland (1853)

·  Masterton (1906)

·  Wellington (1862)

·  Hokitika (1866)

·  Nelson (1862)

·  Lincoln (1863)

·  Dunedin (1852)


Find the one nearest your place! Are you feeling warmer yet?


Here are all the adjustments, expressed in degrees Celsius per hundred years:

No Global Warming in 351 Year British Temperature Record

The Carbon Sense Coalition then commented:

The Central England Temperature (CET) record, starting in 1659 and maintained by the UK Met Office, is the longest unbroken temperature record in the world. Temperature data is averaged for a number of weather stations regarded as being representative of Central England rather than measuring temperature at one arbitrary geographical point identified as the centre of England.

A Scottish Chemist, Wilson Flood, has collected and analyzed the 351 year CET record. Here is the comparison of the 18th Century with the 20th Century. See more here.

When Results Go Bad


Willis Eschenbach likewise has found how another researcher Professor Karlen could not get the local temperatures to agree with the IPCC assessment for the Nordic countries. This is what his analysis showed.

This is what the IPCC showed.

Next Willis turned his attention to Australia. “NASA [GHCN] only presents 3 stations covering the period 1897-1992. What kind of data is the IPCC Australia diagram based on? If any trend it is a slight cooling. However, if a shorter period (1949-2005) is used, the temperature has increased substantially. The Australians have many stations and have published more detailed maps of changes and trends.

The folks at CRU told Wibjorn that he was just plain wrong. Here’s what they said is right, the record that Wibjorn was talking about, Fig. 9.12 in the UN IPCC Fourth Assessment Report, showing Northern Australia (below, enlarged here).

Here’s every station in the UN IPCC specified region which contains temperature records that extend up to the year 2000 no matter when they started, which is 30 stations.

Still no similarity with IPCC. So I looked at every station in the area. That’s 222 stations. Here’s that result:

The answer is, these graphs all use the raw GHCN data. But the IPCC uses the “adjusted” data. GHCN adjusts the data to remove what it calls “inhomogeneities”. So on a whim I thought I’d take a look at the first station on the list, Darwin Airport, so I could see what an inhomogeneity might look like when it was at home.

Then I went to look at what happens when the GHCN removes the “in-homogeneities” to “adjust” the data. Of the five raw datasets, the GHCN discards two, likely because they are short and duplicate existing longer records. The three remaining records are first “homogenized” and then averaged to give the “GHCN Adjusted” temperature record for Darwin.

To my great surprise, here’s what I found. To explain the full effect, I am showing this with both datasets starting at the same point (rather than ending at the same point as they are often shown).

YIKES! Before getting homogenized, temperatures in Darwin were falling at 0.7 Celcius per century...but after the homogenization, they were warming at 1.2 Celcius per century. And the adjustment that they made was over two degrees per century...when those guys “adjust”, they don’t mess around.

Intrigued by the curious shape of the average of the homogenized Darwin records, I then went to see how they had homogenized each of the individual station records. What made up that strange average shown in Fig. 7? I started at zero with the earliest record. Here is Station Zero at Darwin, showing the raw and the homogenized versions.

Yikes again, double yikes! What on earth justifies that adjustment? How can they do that? We have five different records covering Darwin from 1941 on. They all agree almost exactly. Why adjust them at all? Theyve just added a huge artificial totally imaginary trend to the last half of the raw data! Now it looks like the IPCC diagram in Figure 1, all right...but a six degree per century trend? And in the shape of a regular stepped pyramid climbing to heaven? What’s up with that?”