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McDavitt on what the weather did in 2009

By Guest Author • 24/12/2009 • 3


Metservice’s weather ambassador Bob McDavitt has compiled his annual review of weather trends for the previous year.

Click on the presentation below to view in full-screen mode or to download.

[slideshare id=2772724&doc=2009review-091223221454-phpapp02&type=d]

3 Responses to “McDavitt on what the weather did in 2009”

  • Anyone like to explain to me ( in simple terms ) why the New Zealand Air Temperature Graph suggests this year is well below the mean?. Is the graph a true reflection of the measurements?.

    Visually, the past year area below the long term mean appears larger than the area above, suggesting 2009 is significantly colder than the mean. When I cut and weigh ( yes I know I’m a loser with nothing better to do ), the mass of paper representing the area below the LTM is 12.0 mg, and above 6.6 mg.

    I assume the process of graphing or averaging may be responsible for graphing errors, but given the contentious nature of the climate claims, perhaps a little more clarification is required?.

    Was 2009 colder than the LTM, and what are the year-to-year trends.. If it’s also the hottest decade in NZ, I assume the error bars on the temperature measurements and calculations are relatively small, justifying such a claim. Is there a similar graph anywhere with error bars?.

  • whoops – tab key was wrong one to use when typing in a table…it stored my reply instead of tabbing.

    The following table is compiled from NIWA’sa individual monthly climate summaries for the past year for New Zealand , obtainable from http://www.niwa.co.nz/our-science/climate/publications/all/cs/monthly (Dec 2009 is still being computed so I’m using Dec 2008 instead)
    National Average difference from Long Term Mean
    Dec 15.8 0.2
    Jan 17.6 0.6
    Feb 17.5 -0.3
    Mar 15.1 -0.6
    Apr 13.4 0.1
    May 9.0 -1.6
    June 7.5 -0.7
    July 7.3 -0.4
    Aug 10.2 1.7
    Sep 10.6 0.3
    Oct 10.6 -1.4
    Nov 13.6 -0.1

    average for year 12.4 -0.2

    so the year ending Nov 2009 was on the cool side by -0.2c, slightly lower than the long term mean.
    . Better to use the actual numbers rathe than cutting and weighing graphs- there may be some confusion as to the width and smoothing of the lines.

    I suppose we can dwelve through the NIWA monthly climate summaries and extend this exercise to compute the variations form the Long term mean for the decade ending November 2009 , or a term of our choice, but for this article I was just interested in looking back at 2009.

    bob mcdavitt