Whakatane sunshine: test results released

SHARE THIS: 

The National Institute of Water & Atmospheric Research (NIWA) has reported to the Whakatane District Council (WDC) on the results of tests into accuracy of the district council’s sunshine recording equipment.

24 April 2009

This follows NIWA’s decision to omit WDC sunshine figures from NIWA’s Annual Climate Summary for 2008 on the grounds that the extremely high results required further investigation to determine their scientific validity.

The full text of NIWA’s report to WDC is attached. In summary:

  • NIWA installed an identical instrument alongside the WDC sunshine duration sensor, and has compared data for just over one month.
  • The comparison has found a likely overestimation in the WDC sunshine hours.
  • The overestimation is most likely due to the way the WDC data logger has been set up, possibly a software problem.
  • The set up on the WDC data logger has now been changed (10 April 2009). It now records data in the same way as every other sunshine instrument in New Zealand. This appears to have rectified the problem.
  • At this point, there is no way of accurately determining the amount of overestimation in the Whakatane sunshine data for 2007, 2008, and up to 9 April 2009.

Implications: Where is NZ’s sunniest place?

NIWA’s decision to exclude Whakatane from its Annual Climate Summary meant that Blenheim was reported earlier this year as being New Zealand’s sunniest place for 2008.

The findings mean it is impossible to say whether Whakatane received more or less sunshine than Blenheim in 2008. Media reports that “NIWA has named Blenheim as the sunniest place in NZ” are not correct.

For NIWA’s Annual Climate Summary 2009, NIWA will compare sunshine figures between centres not only for the year as a whole, but also for the 8-month period May-December inclusive. It will be scientifically valid to include Whakatane in the 8-month comparison.

Reporters please note:

The WDC automatic sunshine recorder is not maintained by NIWA. While NIWA was consulted over the type of instrument to purchase, it was not involved with site selection or installation.

For more information, please contact:

Dr Andrew Tait, NIWA Climate Scientist
Tel: + 64 4 386 0562
Mob: +64 27 327 7948

Whakatane sunshine data comparison (179 kb)