Monday, October 24, 2005

Research: Sydney southwesterlys gather speed over tree-free west.

"We think the removal of the forest in western Sydney has allowed storms to move across a little quicker."

Macquarie University physical geography department researchers Professor Andy Pitman and his student colleague, Anna Gero, have discovered that their computer simulations of Sydney weather patterns with and without the original vegetation cover suggest that the changing landscape and specifically the western urban sprawl is also responsible for increasing the violence of some storms.

It also appeared the vegetation loss had changed the dynamics of atmospheric convection, which is a key to forming many thunderstorms that strike Sydney on summer days. Without the vegetation, sea breezes could sweep further inland, changing the location where they collided with winds blowing from the south-west. The biggest storms in the simulations formed over the central business district. Professor Pitman said they first thought the storms were being powered by turbulence caused by city buildings, "but we found it was really the cleared space south of Sydney".

The weather bureau's NSW regional director, Stephen Lellyett, said: "Upon a cursory examination, [the] work is very interesting - it appears plausible that the speed and intensity of systems tracking south-west to north-east could be modified by changes to the behaviour of the sea breeze and be a result of land-use change."
Ok, but how is this on-topic? I do observe how Sydney storms seem to be getting worse and had quietly wondered whether this was due to global warming, greenhouse gas style. If Professor Andy Pitman and his student colleague are right it is good news. The increasing serverity of storms has localised causes, at least to some extent. Re-treeing the backyards, parklands and open spaces of western Sydney could help create a storm-break that will help reduce the severity of our storms.

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