Tuesday, 1 August 2017

Hot, dry northerly winds in Melbourne

Last Thursday, as I had a now-fortnightly day of “galloping” around on buses (something everybody concerned about global warming should do to see a key cause in Australia’s dreadful pro-freeway transport policies) I was always expecting heavy rain from the seemingly dense grey clouds as I rode the 901 bus from Dandenong to Greensborough. However, very little rain fell – most of it on a return-home 250 bus trip. Then, Saturday saw warnings from high winds and showers – yet, again no rain fell.

Whilst the rapid poleward spread totalling about 800 kilometres (seven-and-a-but degrees of latitude) in the past fifty years of the winter Hadley cell is a key factor – and remember it is known that at Mesozoic and Paleegene CO2 levels of around 2,000 ppm there was no winter Ferrel Cell and hence no winter “storms” whatsoever – most of Victoria this May and July has not been so dry as Melbourne.
March 2017 rainfall percentages
Here, for March 2017, is a pattern not far removed from some super-monsoon months in the past where storms interact with weak fronts to produce rain over South Australia and western Victoria. This was seen as early as 1903 after the driest calendar year in Australia’s history.
April 2017 rainfall percentages
Like March, this is not inconsistent with super-monsoon months with heavy rainfall in western Victoria. Vis-à-vis past wet Aprils like 1932, 1935 and 1974, there was fewer than half as many fewer actual rainy days – which should have been more of a warning about runaway, largely Australian-caused (both directly through actual emissions and indirectly through selling coal and hugely CO2-intensive lithophile metals) global warming continuing.
May 2017 rainfall percentages
Here is something rather different. One can see that southeastern and central Victoria were very dry, yet the Wimmera, Western Plains and Tasmania (except the south and Derwent Valley) were wetter than average. So was the south coast of New South Wales, although the north and central coasts (not shown) were dry.

This is very different from May 2003 (below) whereby – although there were some similarities within Victoria – the north and central coasts of New South Wales were wet and northwestern Tassie much drier:
May 2003 rainfall percentages. Note the different patterns in Tasmania from last May.
May 2003, like May 2001, reflected depressions much further north than in last May, as reflected by wet conditions on the edge of the Western Australian Wheatbelt. In that sense it is quite similar to a month like June 1963, during a period when the Hadley cell ended at Carnarvon or more northerly (as in that winter which was one of the wettest rainy seasons on record in southwestern Australia) rather than nearer Bunbury:
June 1963 rainfall deciles (most precise figures to avoid the massive influence of Australian greenhouse gas emissions)
One can see the maximum all along the New South Wales coast rather than just on the south coast from one storm on 20 May this year. In June 1963 there was a long run of low pressure systems for the first ten days between Perth and Sydney, bringing essentially continuous rain. The diagrams below illustrate just how profound the shifts in pressure systems have been due to Australian freeway building and consequent greenhouse gas emissions:
Comparative synoptic positions for this year’s May and June vis-à-vis pre-AGW June 1 to 10 1963. Note how the subtropical ridge has shifted ten degrees poleward all through the southern hemisphere in the lower chart. Note also the Tasmanian block in June 1963 
Australian rainfall figures for June 2017 itself are a graphic illustration of the changes in climate due to the Lonie Report and other efforts to fund roads rather than constitutional amendments to ensure every solitary cent of Australian public and private money be spent on more greenhouse-efficient rail rather than on road or air transport:
June 2017 rainfall percentages
In accordance with theories making Australian transport and energy policies the primary and most essential culprit for observed climate changes, the extreme dryness over so wide an area as shown on the June 2017 composite chart is quite unrivalled. Perth, Canberra and Hobart were especially dry, but only the coast of New South Wales directly in the Trade Winds received substantial rain.

The daytime weather in Melbourne was a delightful 15˚C for the opening two weeks of June before we left for hot and humid Taipei – which I did not enjoy at all – but the nights were so cold as to virtually freeze my right hand in our poorly insulated plasterboard home when I sat at the computer until 01:00.

July 2017 rainfall percentages
The map above is apart from the eastern coast of Tasmania and the southern coast of New South wales very like May. It’s striking how dry those areas with a southerly aspect are vis-à-vis the Wimmera and even those areas on the opposite side of the Divide from Melbourne – which are by no means so wet as they would be if such obscene projects as CityLink, EastLink and other freeways and highways had had their funding redirected wholesale in 1980 to mass public transit.

The map is very much drier than remotely similar maps from before the Lonie Report. The famously windy September 1941 – probably the windiest month ever in most of southeastern Australia – is a good illustration:
September 1941 rainfall deciles. These are a bit like last month shifted 800 to 900 kilometres (by removing Australian greenhouse gas emissions) equatorward
Notice that the basic pattern is not that different if one realises that vis-à-vis today’s climate largely controlled from the headquarters of Australia’s largest coal and mining companies – and their allies in VicRoads – the Hadley Cell’s limit lay about eight degrees closer to the equator. That is roughly the distance from Melbourne to Walgett, or from Northcliffe to Shark Bay, or from Adelaide to Coober Pedy!

So, if we place Melbourne near Bourke, one can almost imagine the dry, hot westerly winds New South Wales had in September 1941. These dry winds seen here in Melbourne would still be around Bourke if Australia had had a sane transport and energy policy for the past four decades!

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