Wednesday, September 26, 2007

As soon as the sun rises, so does the temperature

We previously found that overnight temperatures have not increased, with all of Midnight, 3am and 6am not having any significant increase in temperature, hence providing strong evidence that Australian temperature have not increased overnight. This despite increases in the daily minimum.

But what happens when the sun makes its appearance? How will the temperature record respond then? Using our designated Australian weather stations, we found that at 9am, since 1943, we have had a very significant increase in temperature as shown on the graph below:

The increase is highly significant (t = 5.5, p < 0.01) and is increasing at a rate of 1.1 degrees Celsius per 100 years. This is, as one would expect, very strange. In that how can we have such a huge and significant increase at 9am and yet 3 hour previous have no swings in temperature at all? What is causing this massive sudden increase at 9am? Could it possibly be the sun?

Well lets have a look at Noon and see if the same issue is occurring.

And yes, as shown on the graph above, one again a big and significant (t = 4.3, p < 0.01) increase in temperature is occurring. The increase is at 0.99 degrees Celsius per 100 years.

So here we have a situation that at Midnight, 3am and 6am we detect no significant increases or decreases in temperature since the second world war. The suddenly at 9am and Noon, the temperature increases suddenly and dramatically.

Australia is definitely heating up. But maybe its only when the sun is out? We'll look at 3pm, 6pm and 9pm next.


Peter Hartley said...

I find your analysis very provocative. It certainly would appear to be important evidence for helping us decide what has been causing recent climate change. I am surprised that you appear to be the only person looking at temperature trends for a fixed time of day. Do you know anyone else who is doing this for other continents?

ILJAY said...
This comment has been removed by the author.
Raging Tiger said...

Don't you see that sunrise also coincides with the time when fat people start getting into their 4x4's to go to work :-)

Jonathan Lowe said...

Hi Peter Hartley,
unfort. no-one in the scientific literature has done temperature analysis based on time of day. Maximum and minimums have only been looked at, which I believe has a very dubious statistical relevance.

I suggest you read this article on maximum and minimum temperatures.

Ralph said...

Hi Johnathan,

this is very interesting. Do you know if the GCMs produce compatible results (i.e., no warming trend at night, genuine warming trend during the day) or do they predict warming 24 hours a day?

philip said...

ralph, CO2 driven warming predicts less cooling at night and this is what the GCMs show (to the extent they are a realistic model of climate). Jonathan's Analysis shows more cooling is occuring at night. Clear evidence (conclusion proof IMO) that CO2 is not a significant driver of temperatures.

When the history of this gets to be written, one of the key errors that will be highlighted is that increasing minimum temperatures were interpreted to mean increasing nighttime temperatures and decreased nighttime cooling.

It's surprising how few people know that minimum temps usually occur in the daytime.

BTW, you really need to publish this. I'm willing to bet it will be one of those studies thats mostly ignored when its published but gets widely quoted 20 or 30 years later.

BTW, there are a couple of post about your work in the TOB thread at Climate Audit.