Monday, September 24, 2007

Australia not increasing in temperature overnight

Previously we showed that Australian temperatures since world war II have increased dramatically. Maximum's and minimum temperatures have both increased at a significant rate.

However what is happening to overnight temperatures? We have also previously discussed the terrible statistical technique of somehow defining the average temperature as being the average of the minimum and maximum and have long suggested that time based temperatures, where the time is kept constant (unlike max/min temps), is a far better way to analyse temperature and will also provide a lot more meaningful information.

So lets have a look at what is happening for Australian temperatures overnight. In particularly Midnight, 3am and 6am.

As shown below temperatures at midnight show no obvious trend, and statistically there is no significant increase or decrease in temperature (t = 1.6, p = 0.1)

Similary, at 3am as shown below we have also found no significant increase or decrease in temperature (t = 1.27, p = 0.2).

And not surprisingly, also at 6am as shown on the graph below, we have found that Australia has not recorded any significant increase or decrease in temperature (t = 1.3,p = 0.17)

So if Australia is not warming up at night, then how come we have seen a s significant increase in minimum temperatures? We will answer that question shortly, but in our next article we will look at what happens to Australia's temperatures during the day, starting off in the morning at 9am.


philip said...

Jonathan, did you manage to get data on time of day for min and max temperatures? That would make an interesting analysis.

Jonathan Lowe said...

It would make great analysis. I have requested it, but it is not readily available. More recent stations have minute by minute temperature readings and hence have the time of max/min. However these stations have only come into existence in the last decade or 2.