permaculture

[Russ Grayson <pacedge@magna.com.au>]

On Monday, September 22, 2003, at 10:52  AM, rmhoward@omninet.net.au wrote:
> In Perth there is a distinct daily sea breeze which occurs in summer. In the morning, 
> summer easterlies take pollution out over the sea and this pollution is bought back on 
> the sea breeze in the afternoon. Air studies in Perth in the 1980's established that 
> there was a hlaf hour daily spike in pollution levels as the sea breeze came in with 
> pollution levels rising to up to 10 times the average daily level.
>
> In Sydney the situation is somewhat different since there is no distinct sea breeze. 

There is a distinct seabreeze in Sydney that flows from the north-east on summer afternoons. During the hot summer mornings and early afternoons, the sun heats the land and air over the region west of the city, causing the warmed air  to rise. Cooler air flows in from the north east, from the sea, to replace this rising warm air. The range of the effect varies but it is noticeable in the seaboard suburbs and some distance westward of the city. It is generally not noticeable in the city's western suburbs.

The sea breeze is one of the factors our organic gardening classes (Eastern Suburbs Community College) identify as part of site analysis for garden design.

> However, the Perth measurements do indicate that, when the winds turn due to diurnal 
> effects( ie a sea breeze) or because of meteorological conditions i.e. a change in the 
> weather, then the maximum period of pollution is at the time of the wind change. 

The effect with air pollution in the Sydney Basin, I believe it was first identified by the CSIRO, is that after the polluted air body moves seaward, it returns to an inland region south-west of the metropolitan area within three or so days. There is can remain for some days. This would vary with weather conditions.

It will be interesting to see if more air movement and pollution load studies will be done now that the state government (last week) announced that water conservation, including rainwater tanks, will become compulsory as of mid-2004, as will energy efficiency design factors as part of the proposed Building Sustainability Index.


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Russ Grayson
Media services:  journalism-print/ online/ photo
TerraCircle development aid team, Oceania
pacedge@magna.com.au  Phone/ fax: 02 9588 6931
PO Box 446 Kogarah NSW 2217 Australia
http://www.magna.com.au/~pacedge/
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