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Sydney (Observatory Hill) Comparison site

Discussion in 'Daily & Chat' started by Steve777, Jul 6, 2020.

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  1. Steve777

    Steve777 One of Us

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    The Sydney Observatory Hill Comparison site (No 66214) has been up and running for nearly three years. It was discussed from time to time on Weatherzone and has popped up once or twice here.

    While it would be mainly of interest to Sydney weather geeks, it does show how the characteristics of a site can affect observations. In the case Sydney's prime weather station, that’s high exposure to the North East quadrant. We have two sites about 160 metres apart which can return very different observations in certain conditions.

    Here are the average maxima and minima at the two sites for the Financial Year 2019-20:


    [​IMG]

    The comparison site experienced slighly cooler minima (difference under 0.5 deg) at all times of the year. Maxima are slightly warmer (difference again under 0.5) at all times of the year except high Summer, where the Comparison site maxima are about a degree warmer.

    December 2019 was hot and very dry. January was mostly hot and dry. Although it finished with about 70% of the average rainfall, this nearly all fell in a three day wet spell in the middle of the month. Both December and January both had lots of hot, sea-breezy days where the comparison site can be two degrees or even 3 warmer. February was humid and wet with fewer hot days and the difference was smaller.

    I would speculate that in cool Summers like 2011-12, 2007-8 or some of the woeful Summers we had in the 1990s, dominated by Southerlies and SE'ers, the difference between the two sites in Summer would probably also not be great.
     
    #1 Steve777, Jul 6, 2020
    Last edited: Jul 6, 2020
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  2. Trail Blazer

    Trail Blazer Part of the Furniture

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    Nice analysis Steve.

    At what point does the comparison site take over? I understand it’s better located, further away from buildings etc
     
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  3. Steve777

    Steve777 One of Us

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    So far as I know, there is no planned date. I recall that a meteorologist (Blair Trewin?) posted on Weatherzone that this was dependent upon development plans for the school next to the site, which would render the current site unsuitable for the BOM.
     
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