Tuesday, September 18, 2007

Australian Maximum and Minimum Temperatures

Using Australia's most reliable long term non urban weather stations that have time bed temperatures that go back to at least 1970, we can get a good grasp on Australia's changing temperatures. The stations, as mention previously, are shown below.

The reason why such stations have been chosen is because this sit wants to analyze time based temperature trends instead of the normal maximum and minimums. There is no scientific literature released that does so and I believe the analysis of such information is crucial to determine how and why global warming is occurring.

To start off with, we will look at maximum and minimum temperatures. Temperature anomalies are taken from the average of 1961 to 1990 which is the norm for such analysis.

Shown below is Australia's maximum temperature anomalies:

As one can see, aside from some haphazard temperature swings prior to 1940 we can witness an increasing maximum temperature trend that is strong and significant (t = 5.9 , p < 0.01). It can be said, that without doubt that records of Australia's maximum temperatures have significantly increased since the 1940s. In fact maximum temperatures in Australia have been increasing at a rate of 0.0132 degrees Celsius per year since 1942, or 0.85 degrees in that span of 64 years.

Shown below is the temperature anomalies of minimum temperatures from the selected stations across Australia:

The graph above shows significant decrease in temperature since 1911 (t = -2.1, p < 0.05). However this has generally occurred due to larger than normal positive anomalies from 1911 to about 1940. Should we investigate the temperature swings in minimum temperature from 1940 onwards only we find the opposite has occurred. Minimum temperature has significantly increased from 1942 (amount of data increased substantially from 1942) onwards (t = 4.2, p < 0.01). The rate of increase from 1942 is at 0.0082 degrees Celsius per year or at 0.525 degrees over the last 64 years.

This increase, whilst still as large as maximum temperature increases is still large and significant.

So how does this compare to the Australian Bureau of Meteorology's graphs? We'll look into that next.

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