Wednesday, December 22, 2010

Rainfall and inflow: a summary

At present, I am still waiting on data. However, if I combine the two stations at this point, I get a value of 861.8 millimetres of rainfall thus far this year. Based on extrapolation, this would indicate that we have received approximately 160,000 megalitres of inflow.

The rainfall would thus be enough to blow through my limit of 850 millimetres. However, I am not certain that I am willing to concede as yet, even though there are nine days to go for the year and a little more rain is predicted to fall just after Christmas. As the station that I am using showed around 100 millimetres less rainfall by November, it is possibly that it has received 12 millimetres less in December. But we will see. ;)

Temperature datasets

As I keep losing track of these, I want to put them all in one place:






STAR mid-troposphere data (this is not directly comparable with UAH, but can be compared with the RSS mid-troposphere data).

Monday, December 13, 2010

Oops ...

I have made an embarrassing discovery: I have been using the wrong rainfall data for Canberra. The rainfall data that I have been using was from here:

I had made the assumption that this data was the same as the date from here:

This is not the case, as I would have realised had I been paying attention:

"Source of data

Observations were drawn from Canberra Airport {station 070351}.

Weather observations for Canberra were previously taken at a nearby site {number 070014}. These can be seen on the "Canberra Airport" Daily Weather Observations; you may need to consult these to get all the relevant data."

My predictions were based on the data from station 070014, as the data from station 070351 only goes back to the middle of 2008. This can be seen here:

So, at the moment it is not clear that my prediction has been falsified. I think that it has, but I will not know for certain until some time early next year.

To be sure that this is the data that I used, please read this post:

You can check the 10-year averages for temperature and rainfall from the data obtained from site 070014 and see that the slope between them is practically identical to the one displayed in the above post. The very small difference is due to slight corrections in the 2009 data, the latter part of it being still provisional in January 2010.

To go back a step, you can bring up the data by entering the site number into this web page:

So: we will soon see if my prediction has been falsified (which it likely has been).

Another consequence of this error on my part is that inflow for the rest of the year will be higher than it otherwise would have been, as the rate of inflow for megalitre has increased (due to there having been less rainfall at station 070014). Thus, my estimate for the inflow - and I must estimate it, because it cannot be measured as the dams are all above 100 per cent - will be greater. At present, that does not matter, as we have not had much rain since reaching 100 per cent. But rain is expected soon.

Tuesday, December 7, 2010

Prediction Shortgevity

Following on from my discussion about longevity comes something about the opposite: my short-lived prediction regarding Canberra rainfall. We have received a staggering 899 mm thus far this year, blowing past my 850 mm limit. Thus, my statistical analysis that pointed to technical desert conditions for Canberra by 2050 has been proven false.

So the key now for me is to keep watching to see where the evidence points. What is obvious now is that my conclusion was not warranted from the data, and I needed more data - data which I now have. But that is how science works: you build a model from observations and use that model to make predictions about the future, understanding that falsifying those predictions falsifies the model.

I will continue to track the rainfall and inflow (although with Canberra dams now at 100 per cent, tracking excess inflow is a little difficult - I will have to make some assumptions about extra inflow, and I am looking at what those assumptions might be at the moment.) We have received 142,000 megalitres of inflow thus far this year. What I might do is slightly increase the overall average to account for lost water. It should be pointed out that this amount of inflow is still significantly lower than the average.

Wednesday, December 1, 2010

Life expectancy for my age cohort

I have just been doing some calculations on my age cohort based on the observed improvements in life expectancy for Australians over the last 20 years. If those improvements are replicated every 20 years over the next century, the median life expectancy of all those aged 40 becomes 127.5, with those people living most of the last 40 years of their lives with a health approximating those in their early 70s today. They would have reached statistical immortality (see a previous post on this) at around age 90. Some of that cohort should live much longer than that, and there is a slim possibility that some of them could be alive hundreds of years from now.

That gives me reason to hope that I might be alive - doddering, perhaps, and dreaming of the past but alive - in the year 2100, an interesting milestone to me because (a) I am human and love nice round numbers and (b) it is a year about which there is much speculation in science fiction novels and roleplaying games (see (a)).

While I am a pessimist regarding climate change, I am also an optimist: while I believe that humans are going to cause a lot of suffering for ourselves and other species over the next century, I think that we as a species will pull through it and have an amazing history to write on our planet, on other locations in the solar system and among the stars. I would like to see more of that history. :)