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Walter John

Cilmate in Australia

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Walter John

A few people ask me about our weather here in Australia. I found these points from our Bureau of Meterology quite good.

With a smaller continental area separated from polar regions by the Southern Ocean, Australia escapes the harsh outbreaks of true polar air which invade northern hemisphere continents during winter. Northern hemisphere continents have a greater temperature contrast between summer and winter.

The most notable feature of Australia's climate is its high year-to-year rainfall variability. This is influenced by the Southern Oscillation which is driven largely from the tropical Pacific Ocean and overlying atmosphere. The phenomenon known as El Niño is part of this system and makes a significant contribution to this variability. Even though the El Niño-Southern Oscillation is linked to persistent seasonal anomalies in many parts of the globe, Australia is one of the most affected continents, experiencing major droughts interspersed with extensive wet periods. Frequencies of tropical cyclones, heat-waves, bushfires and frosts are also linked to the Southern Oscillation.

The Southern Oscillation refers to an oscillation in air pressure between the southeastern and southwestern Pacific waters. When the eastern Pacific waters increase in temperature (an El Niño event), atmospheric pressure rises in the western Pacific and drops in the east. This pressure drop is accompanied by a weakening of the easterly Trade Winds. Together with El Niño, this phenomenon is known as ENSO, or El Niño-Southern Oscillation. The strength of the Southern Oscillation is measured by the Southern Oscillation Index (SOI), the normalized surface air pressure difference between Darwin, Australia and Tahiti.

Retrieved from "http://en.wikipedia.org/wiki/Southern_Oscillation"

Given Australia's low and variable rain, there is environmental concern about the sustainable management of surface water, its use, its quality and even its very existence in some places.

Our plants and animals have evolved on a geographically isolated continent, through a time of a slowly drying climate, combined with continuing high variability. The uniqueness of much of Australia's flora and fauna is thus at least partly due to these features of our climate.

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philinsydney

Also, Wal, I believe that Western Australia lost its rainforest during the last Ice Age, when conditions were even harsher than now. There are now no palms, tree ferns or mangroves native to the south-west of W.A.

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Tyrone

(wrigphi @ Oct. 04 2006,07:09)

QUOTE
Also, Wal, I believe that Western Australia lost its rainforest during the last Ice Age, when conditions were even harsher than now. There are now no palms, tree ferns or mangroves native to the south-west of W.A.

There are a small patch of mangroves at Bunbury. The most southern mangroves in the world I believe.

It would have been an interesting place when it was tropical, and I wonder what species there were. The south west does have a lot of cycads of the Macrozamia variety, and treeferns have naturalised in some areas.

regards

Tyrone

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gebe

I thought we had mangroves here in Nz or is bunbury some where south of us?

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Tyrone

(gebe @ Oct. 15 2006,23:22)

QUOTE
I thought we had mangroves here in Nz or is bunbury some where south of us?

Bunbury is about 33.5S so if you have them in NZ you would undoubtedly have the most southern mangroves in the world. I'm interested to know where in NZ mangroves grow. They'd probably have some warm ocean current feeding them.

regards

Tyrone

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Jerry@TreeZoo

There are Black Mangroves (Avicinea?) growing in the Bay of Islands NZ.  They are  not the Red mangrove with the prop roots hanging down, but they have pneumataphores, or pencil like roots that grow out of the mud to above the waterline to exchange gases.

Jerry

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Don Little

Wal,

My wife and I had the opportunity to visit Brisbane last year and we absolutely loved it.  We statyed right on the river at the marriott Brisbane.  The weather was perfect and the people were very friendly to boot.  We visited Mt Cootha and the Roma Parklands along with the park that is over by the mangrove board walk, can't remeber the name of it,  I was impressed with what I saw.  My question is do you ever have frosts or freezes there in Brisbane?  How cold would you say your coldest nights are during the winter months?  If we ever moved to Austrailia, Brisbane seems like the perfect place once you get used to the differences in driving which was very interesting and fun.

Thanks, Don

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