Sunday, May 20, 2007

The sunshine state: North Queensland

Now, onto Queensland, often called the sunshine state, so it will be interesting to see what effect the sun has on this state’s temperatures. To start off with we will go to the far north. Data comes from several stations including Cooktown and Cairns airport. The data also is pretty good, with maximum and minimum temperatures spanning back to 1910, and all time based weather readings back to 1943, with the exception of midnight (which seems to be a regular case) only back to 1993.

Maximum temperatures saw a significant raise (t = 4, p<0.01) largely to a significant lower than normal maximum temperatures between 1910 and 1920. Minimum temperatures also saw a significant increase (t = 6, p <0.01).

However surprisingly, 9am was the only time based temperature that saw a significant increase in temperature (t = 3.8, p < 0.01). Temperatures at 3pm saw no increase in temperature (t = -0.5, p = 0.6). This ties in with the fact that the only reasons why we saw a maximum temperature increase was because of very early low maximum temperatures which are not accounted for in the time based temperatures.

However the usual pattern was found when looking at the rate of change of temperatures between adjoining times. 9am recorded a significantly higher temperature anomaly than 6am (p<0.01) and 6pm showed a significant lower temperature anomaly than at 3pm (p<0.05), despite the last few years being positive. Hence indicating that all recent warming in north Queensland is due to the suns output.

Temperature analysis between 3am,6am and the minimum temperature, saw the minimum temperature increasing significantly at a rate of up to 1.7 degrees per 100 years in comparison to overnight temperatures. This once again indicates that temperatures at night are not warming up in northern Queensland and that the minimum is only increasing due to the influence of the sun.


Steve M. said...

You say that 9am was the only series with a significant rise and attribute this to the maximum temperatures being early in the day (i.e. 9am is warmer than 3pm). Since the mean temperatures at 3pm (9am) are typically -using Gyndah as my example- ~30 (26) in summer and ~22 (15) in winter, it seems that this would actually need looking at before you can claim it.

Is 9am consistently warmer than 3pm across the Queensland stations?

I'd like to see a plot of (time of peak temperature) against (year) for, say, January and July. If you're right, then the plots should start with the 3pm bin showing the peak temperature most often and move (as the years pass) to the peak being observed at 9am.

(You may also need to treat the tropical and sub-tropical stations differently)

Steve M. said...

One more thing... space-based observations of the total solar irradiance show a downward trend (modulated by the 11-year activity cycle) since the measurements began in 1978. This trend exceeds the instrumental uncertainty.

While the solar effect on climate is well-established from paleoclimate studies, it would seem that if solar radiation was the zeroth order forcing then we'd have seen a decrease in global mean temperature since '78. Unless there was some other important forcing...

Jonathan Lowe said...

you are right steve m (first post). I'm not quite sure that i actually meant that and will delete that little spiel. temperatures around 3pm are hotter than at 9am in tropical nth qld, but have not seen an increase at that time over time. there is still a significant increase from 9am as opposed to 6am and a significant decrease at 6pm from 3pm which still indicates the suns influence.

Elizabeth said...

I am wondering if you can extend on your comments in a post about a link between an increase in day time temperatures and solar influence. Your lovely statistics are nice but you are not linking it with sounds science to anything.

Phil_B said...

I'll summarize what Jonathan's analyses show.

Daytime temperatures are increasing relative to nighttime temperatures, and changes to maximum and minimum temperatures reflect increasing daytime temperatures and do not reflect a more or less compensating increase in nighttime cooling.

Mean temperature calculated (as it is) from the average of maximum and minimum is giving a misleading indication of warming in the sense of heat gain.

As the to the cause (assuming a single cause), it can only be the atmosphere is allowing increased incoming and outgoing radiation (i.e. it's not solar).

I'd also like to see whether the time of the daily minimum and maximum temps have changed. In addition, I'd like to see if places like China where atmospheric particulates have increased show similar trends.

Phil_B said...

Jonathan, Someone else has done a similar analysis as you and found the same results.


It has been shown that the metric TI correlates well with the greenhouse effects of water vapor as indicated by precipitation. It was further demonstrated that TI could be used to discriminate between an increase in atmospheric thermal inertia (greenhouse effect) and an increase in input energy. This property was used to demonstrate that the warming trend between 1973 and 1994 was due to increases in input energy and not increases in thermal inertia. There was no significant correlation between the rise in CO2 and the TI metric.

Jonathan Lowe said...

yes i noticed that Phil, interesting read