Climate Change Australia – Did A Switch In Gauges Cause Melbourne’s Temperature “Rise”?

Posted on Tue 09/30/2014 by

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Bolt New 01By Andrew Bolt ~

ClimateChangeAustraliaJo Nova:

Here’s a strange change. After 160 years of fairly constant maximum temperatures, the raw Melbourne records take a sudden step up by 0.7 0C in 1996. Coincidentally (or not) that is the same year that the automatic gauge was installed. The new electronic equipment is much more responsive to short peaks and dips compared to thermometers. Could the step up be due to the better resolution? It’s by no means definitive — these are yearly averages, not monthly, and it may be a real climate shift and not due to the equipment. The obvious question is whether this sort of jump occurs in other stations where AWS (automatic weather stations) were installed. That would have profound implications if it did, but surely it would have been noticed already? 

Tom Quirk:

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During the 1990s the Bureau of Meteorology (BOM) started to install automatic weather stations. The minimum and maximum temperatures along with temperature readings every 30 minutes were recorded electronically. The weather stations used thermistors rather than mercury or alcohol thermometers for temperature measurements. Thermistors are electrical resistors that are very sensitive to temperature changes.

The Melbourne annual maximum temperature readings are shown in Figure 1. There is an unusual feature in the record as shown occurring in 1996. It is a break with a difference of 0.7 0C. The two straight lines are a best fit to the measurements and the difference is calculated from the lines at 1996.

Andrew Bolt is a journalist and columnist writing for The Herald Sun in Melbourne Victoria Australia.

Andrew Bolt’s columns appear in Melbourne’s Herald Sun, Sydney’s Daily Telegraph and Adelaide’s Advertiser. He runs the most-read political blog in Australia and hosts Channel 10’s The Bolt Report each Sunday at 10am. He is also heard from Monday to Friday at 8am on the breakfast show of radio station MTR 1377, and his book  Still Not Sorry remains very widely read.

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