Wednesday, April 18, 2007

East of Perth

It's been a while since we've analysed Australian data so lets ave a look at the area of east of perth that extends to Kalgoorlie - famous for it's mining, drinking and womenising.

There is no significant increase or decrease in maximum temperatures (t=-0.9, p=0.36), however a significant increase in minimum temperatures was found (t=4.4,p<0.01).

Despite this minimum temperature increase, no significant increases in temperature was found at midnight (t=0.5,p=0.6) or 3am (t=0.25,p=0.8). However, significant increases were found at 6am (t=2.3, p<0.05), 9am (t=3.3,p<0.01) and Noon (t=2.4,p<0.05). The reminder of the day so no significant increase in temperature (3pm: t=1,p=0.3; 6pm: t=-1,p=0.3; 9pm: t=0.8,p=0.4).

There is ample data for this region, dating back to 1943 with the exception of temperatures at 9pm which only go back 17 years. Hence we are finding an increase in temperature in the early hours of the day when the sun first makes its appearance.

When looking at adjoining times, we find no significant difference between temperatures at 3am and midnight (p=-0.4), however we do find significant differences between 6am and 3am (p<0.01) as well as between 9am and 6am (p<0.05). No differences in tempertaure were found between Noon and 9am (p=0.6), however we do find a significant decrease in temperature between 3pm and Noon (p<0.01) and between 6pm and 3pm (p<0.01).

Hence this tells me that in south eastern Western Australia, minimum temperatures are only increasing because of a sudden increase in temperature around the 6am and 9am mark. Whatever is happening at this time, the increase is so big that it offsets any increase later on in the day.

It is kind of obvious that this is the time in which the sun rises. Hence, it might sound strange, but an increase in minimum temperatures along with no increase in maximum temperatures might well have something to do with the strength of the sun in areas east of Perth.

Incidentally, no significant changes in rainfall was observed since 1910 in the area (t=0.6,p=0.55)


Count Iblis said...

What's the confidence interval for the temperature increase per century?

Jonathan Lowe said...

you love your confidence intervals count, and as stated before, the majority of statisticians dont use them as they see them as inferior and provide less information than p values. but anyway

Max: (-0.65, 0.24)
Min: (0.42, 1.1)

Count Iblis said...

Why not calculate a confidence interval for the average temperature increase of all the places you have looked at and submit the results of that to some climate science journal?

You could distinguish between day and night temperatures etc.

Jonathan Lowe said...

a caloboration of all the stations is the plan count, and this will be done when I've looked at every one. However, I believe that it is important to analyse every single area by themselves as well as this provides greater information. Weather patterns in different areas are different, and this has been proven here.

Normally in research we are given the average temperature across the world, however as I have shown some places are heating up, and others are doing anything but. If global warming was caused by CO2 levels, I would expect a lot more similarity in the temperature data between stations and areas around Australia.

Phil_B said...

The only cause I can think of for increased heating in the morning and increased cooling in the (later) afternoon is a decrease in atmospheric particles.

The same effect would cause an increase in minimum temperatures which typically occur shortly after dawn, just before solar heating reaches a higher level than radiative cooling.

I'd be curious to know if you find any relation with volcanic eruptions, particularly Pinatuba.