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Tampering With Alice

May 1, 2013
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By Paul Homewood

 

image

Figure 1

http://data.giss.nasa.gov/cgi-bin/gistemp/show_station.cgi?id=501943260000&dt=1&ds=12

 

According to the above chart from GISS, there has been a steady warming trend at Alice Springs in Australia, something like a degree and a half since 1940. This may look perfectly reasonable, until we examine the original temperature records, and find that they are totally different.

 

Until 2011, GISS used the raw data, which they then adjusted for UHI, what they refer to as “homogenisation”. Since then they have altered their system, which now uses  “Adjusted GHCN data” as the input. Fortunately, GISS still show the raw data up to 2011 on their website, and this is plotted in Figure 2.

 

 

image

Figure 2

http://data.giss.nasa.gov/cgi-bin/gistemp/show_station.cgi?id=501943260004&dt=1&ds=1

 

Lo and behold! Where has the temperature increase gone? Let’s compare the numbers for 1942 and 2011. (The choice of 1942 will become apparent later).

 

Year Raw GHCN Adj
1942 21.77 20.04
2011 20.22 20.16
Inc/(Dec) (1.55) 0.12

 

So a drop of 1.55C has been adjusted into an increase of 0.12C, a total change of 1.67C. What do the Australian Bureau of Meteorology (BOM) have to say? Their graphs for maximum and minimum temperature are shown below, and both show that temperatures have been essentially flat since the station opened at the airport in November 1941. (Prior to that, the station was a few miles away in town, hence my starting comparisons in 1942).

 

015590_36_13_1494414366208755300

http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_display_type=dataGraph&p_stn_num=015590&p_nccObsCode=36&p_month=13

015590_38_13_8764744362687202407

http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_display_type=dataGraph&p_stn_num=015590&p_nccObsCode=38&p_month=13

 

The adjusted temperatures, as now used by GISS, are the same as the actual data from BOM for recent years. It is the historical data that has been adjusted downwards. For instance, compare the numbers for January 1942:-

 

GISS 26.2C
BOM 27.9C

 

If the Australian BOM are happy with their temperature record, why are GHCN adjusting it? The metadata shows that the station has been at the same site, to within a few yards, since it was established in 1941. It also shows that there have been no significant changes in equipment, or any change in time of observation. In short, there is no reason at all to suppose the original measurements were wrong.

Furthermore, if any adjustments were to be made, surely they should have been in the opposite direction? The UHI effect must have increased at the airport in the last 70 years, when it has changed from little more than a grass track, to the modern airport seen below. (Even though Alice Springs has a population of 18000, and the site is at an airport, GISS in their ultimate wisdom have decided that no UHI adjustment is necessary).

 

 

As with similar adjustments in Iceland, I asked Bryant Korzeniewski, of the GHCN team at NOAA, last year to provide an explanation of how these adjustments had been arrived at. This is quite a simple procedure for them to carry out, as he confirmed to me. Six months later, despite chasing, I have still to receive an reply. I can only assume that the answer is embarrassing for them.

I will probably get some moron telling me that It’s all explained in the “peer reviewed literature”. Sorry, but I am not that gullible.

 

 

References

BOM data is here.

https://notalotofpeopleknowthat.wordpress.com/2013/05/01/tampering-with-alice/#more-3118

4 Comments
  1. John F. Hultquist permalink
    May 1, 2013 4:22 pm

    The two figures are hard to reconcile. In Fig. 1 there is a peak shown for 1942 that appears to be a bit over 20 and no previous year has a higher temperature. In Fig. 2 that year’s number is about 21.7 with five earlier years higher and several more nearly as high. The change appears to be linked to the year 1933. Note the same shape just prior to that peak in 1942 for about 8 or 9 years. Go back the next couple of years (pre ’33) and the shape has changed. Also, the shift is generally about 2 degrees down in the adjusted Figure 1.

    A computer algorithm, a look-up table, or a person looking at a screen appears to have “decided” to make a significant change in the data. Maybe not a lot of people know why, but surely someone does!

    • May 1, 2013 5:48 pm

      It would be understandable if they had adjusted down the pre 1942 numbers, on the basis that the station was based in the town itself upto then. But after 1942 there is no logic.

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