G'day Dan,
Something that is science. Thank you. That isn't sarcasm by the way. I do thank you for actually going to the trouble to look at the science.
The Monte Carlo method is of use if you are trying to determine a "true" average. But it is of no relevance at all if all you wish to do is look at anomolies over time. A regional analysis will do just fine for that and even ignoring concentrations will still provide a basis for comparison. The more you "adjust" the data for various deficiencis in it, the more prospects your have of manipulating the data.
So if I was faced with the choice of having 5,000 weather stations that had long term daily averages and weighing them to take into account their latitude or to simply compare them year to year, my preference would be the simplest one. Actually I'd do both but the Monte Carlo method does not account for the distribution of oceans and their effect on temperatures or a considerable number of other variables that affect the usefulness of a particular weather station as respresentative of its region. A weather station at a say 30 degrees north on the coast is going to be quite different to one 1,000 kilometres inland. The affect of the moderating influence of the ocean is much greater for most latitudes than the position latitudinally, assuming we are talking comparisons over time.
Having said all that, this has very little to do with Australia. The distribution of weather stations is markedly coastal but in determining whether the "average" temperature has changed over time, it really matters not much at all whether you simply use all available weather stations or you give weight to such things as concentrations of stations, distance from oceans, height etc.
Actually the distribution of weather stations isn't all that bad in Australia if those stations with considerable urban effect are taken out. You still have the centre under-represented but there are stations throughout Australia.
Mr Lowe should be able to demonstrate the various ways of determining an average for Australia far better than I. His expertise is in data analysis, something I have only had to do as part of an overall analysis of the scientific methodologies adopted. I will be greatly interested to see Mr Lowe's take on Australi's temperatures. Actually I'd welcome comments on any mistakes or poor assumptions I've made in this post.
We are at least back to talking about the science of climate and that is a terrific thing.
Regards
Richard
