Gust Of Hot Air
Gust of Hot Air is a blog outlining my own statistical analysis of Australian Weather. I am Jonathan Lowe, and have completed by Bsc(hons) in statistical analysis as well as my Master of Science. I have done 2 years of my PhD
There is a lot of statistical information regarding climate change and I intend to provide statistical analysis into the area to prove if the recent well advertised rise in temperature is at all statistically significant. Results will be uploaded here on a regular basis
Analysis of Australian Temperature - Part 7 - Adjusting temperature for cloud cover
Tue 08 Nov 2011 - 1:15 PM
Website: Gust Of Hot Air
I analysed the relationship between cloud cover and temperature in Australia at certain times of the day. Not surprisingly the results found that increases in cloud cover were related to lower temperatures during the day and higher temperatures at night. Similarly, lower levels of cloud cover resulted in higher day time temperatures and lower night time temperatures.
I have also shown previously
that the cloud cover levels have decreased substantially since 1950.
So what happens if we eradicate the variable cloud cover from the database? In other words, if we keep the cloud cover level and adjust the temperatures, we should be able to see what happens to Australian temperatures at certain times of the day irrespective of any increase or decrease in cloud cover levels.
The following are the standard 8 graphs of temperature anomalies with the trend shown by the light blue line, and also the cloud adjusted temperature anomalies as represented by the regressed red line.
The graphs above might be confusing to some but let me explain.
Basically it shows that when we adjust for cloud cover during that particular year, the temperatures increases at Midnight, 3am and 6am have little difference. The slope of those lines is very similar. However at 9am a massive change occurs. When adjusting for clouds, instead of an increased temperature at a rate of 0.92 degrees per 100 years, it only increases by 0.68 degrees per 100 years, or a 26% less.
This increases even more so as you get to the 3pm time slot. Where previously we recorded a 1.09 degree per 100 years increase, when we account for cloud cover during that particular year, we only see a 0.44 degree increase per 100 years, or a 60% decrease in temperature. Interestingly, this is generally part of the day where the maximum temperature often occurs.
The trend then decreases, and then by 9pm, there is no difference between normal temperature anomalies and cloud adjusted temperature anomalies.
Quite clearly, the only times where clouds make a difference in the long term Australian temperature averages is during the day. The more clouds there are, the less the sun can get through and the cooler it is. Similarly for the opposite.
The graph below shows the difference between the average of the maximum and minimum temperatures in Australia and the average of the cloud adjusted temperature anomalies.
What the above graph shows, is that by using the normal method of calculating the average long term temperature, we have an increase of 1.17 degrees per 100 years, whilst the average of the cloud adjusted temperatures record an average of just 0.54 degrees per 100 years, or 54% less.
Perhaps it is true that we are overestimating how much Australia is warming up by more than double. But there is more to come on this, and in the next post I will look at some more long term trends in cloud cover and what effects they have on temperature, which will have very interesting results indeed.
Alternative GustofHotAir Analysis
Tue 08 Nov 2011 - 12:31 PM
Website: Gust Of Hot Air
Whist I haven't finished my analysis of the temperature, and expect some posts to come again soon, the boys at Bishop Hill have done a fantastic job at analysing it.
This is a must read for followers of my blog and goes into more details about the specifics of why some of the statistics that I have found might be taking placehttp://www.bishop-hill.net/blog/2011/11/4/australian-temperatures.html
Massive rainfall in Australia? The Bureau of Meteorology claim the opposite to their predicitons
Thu 10 Mar 2011 - 1:21 PM
Website: Gust Of Hot Air
Wow, what a summer we've had in Australia. It's been non stop raining everywhere across the continent. So much so that Australia has had its second wettest summer on record. In victoria the rainfall comes even moreso. We recorded over 336mm of rainfall this summer alone, well and truely beating our previous record set back in 1910 of 237mm. The Murray Darling Basin, also had its third highest summer rainfall on record as well.
The year 2010 was quite different to the norm. Australia had the second highest rainfall since records began. Such a huge dumping of rain must have been predicted surely?
Lets look back to the CSIRO's climate change in Australia's website: http://climatechangeinaustralia.com.au/
Here they claim that:
"Projected reductions in precipitation and increases in evaporation are likely to intensify water security problems in southern and eastern Australia"
Ouch! Lower rates of precipitiation? They go on:
"In no regions or season do models suggest a 'likely' increase in rainfall"
Not one single model in any single area project even a likely increase in rainfall? What's wrong with theses models? ANd they continue:
"For 2030, best estimates of rainfall change indicate little change in the far north and decreases of 2% to 5% elsewhere"
Ahh damn, things haven't got onto a good start. So I presume now that the data strongly shows that rainfall is increasing Australia wide, are we going to scrap these models altogether?
Such a shame that the leading experts in weather predictions and climate change in Austraia canot predict the or climate change.
Or can they: (The Bureau of Meteorology on the wettest summer on record in Victoria: http://reg.bom.gov.au/announcements/media_releases/vic/20110228.shtml)
"Whilst any one such event cannot be attributed to global climate change, a recent study of extreme weather events across the globe suggests that there has been an increase in the frequency of such events over recent decades, and this trend is consistent with what we expect under global climate change."
Wow it's been a long time since I've posted.
Going way back to Dec 2009 I see. However, considering that there are plenty of things in the Australian news at the moment with regards to global warming (not least the carbon dioxide tax) and the fact that I didn't release the very last of my analysis on Australian temperatures, and the fact that the amount of rain we have had lately goes far and beyond (and opposite) all that most predicted (except me)....
I thought now was a great time to finish off the series as well as make a few posts about the current climate scenario. So stay tuned.....more is coming very soon!
Analysis of Australian Temperature - Part 6 - Relationship between cloud cover and temperature
Thu 17 Dec 2009 - 11:26 AM
Website: Gust Of Hot Air
One would expect that a greater amount of cloud cover would result in a lower temperature and a lower amount of cloud cover would result in a greater temperature. We should previously
that the amount of cloud cover in Australia has been decreasing since 1950, and we also showed
that temperatures in Australia have been increasing, especially during the middle of the day, and temperatures have not been increasing during the night.
So what influence does the amount of cloud cover have on Australian temperatures during certain parts of the day and night? Shown below are the graphs of cloud cover anomalies verses temperature anomalies since 1950.
So what is quite clear from the above graphs is the clear relationship between cloud cover and temperature during the day. All relationships were significant apart from 9pm and Midnight, where no significant relationship was found. Interestingly, the relationship between cloud cover and temperature at 3am and 6am was positive, in that greater amounts of cloud cover was related to greater temperatures.
This is not that surprising, as cloud cover at night works as a blanket, helping to keep the temperature in. From 9am until 6pm, the relationship is undeniably negative, in that lower amounts of cloud cover is related to higher temperatures, and greater amounts of cloud cover is related to lower temperatures.
This is summarised in the graph below:
Here we can see that the strength of the relationship increases until Noon/3pm and decreases after/before this.
So it is clear that cloud cover amounts have a very strong relationship with temperature, as we previous hypothesised. As we showed previously
that cloud cover levels in Australia, especially during the day, have been decreasing, what effect does this have on temperature?
Can we adjust the temperatures for this decrease in cloud cover? What effect will that have on the long term averages on Australian temperature? We will find this out in the next post.