Will GW increase NZ's sunshine hours?

Manukau heads obs · Fri 05/12/2014 08:52

I put it out there that Global warming is going to increase sun shine hours here

melja · Unread post by **melja** » Fri 05/12/2014 15:20

Thought warmer sea made more clouds

Manukau heads obs · Fri 05/12/2014 15:36

alot of the time, warm air masses pick alot of moisture/cloud over cooler water temperatures...as they warm (the sea surface) up...there will be less of that happening (and a warmer air mass can hold more moisture...so actually everything being equal, will mean less clouds...but given the triggers has more rain potential

NZstorm · Unread post by **NZstorm** » Fri 05/12/2014 19:08

Manukau heads obs wrote:I put it out there that Global warming is going to increase sun shine hours here

Under the climate change scenario the subtropical subsidence ridge will strengthen over the north of the country during the summer months leading to less rainfall and higher sunshine hours. So the Bay of Plenty arguably could become the sunniest part of NZ. And Auckland becomes sunnier as well.

Nev · Unread post by **Nev** » Fri 05/12/2014 19:32

Interesting discussion.

Thought it might warrant a thread...

RWood · Unread post by **RWood** » Fri 05/12/2014 20:41

First we'll have to finish migrating to a consistent measuring method - at present the data is "all over the place".

As a point which might be vaguely related to the subject - poleward migration of the southern ocean jetstream - which may or may not be an artefact of warming - has already had a noteworthy effect on Perth and the SW corner of WA generally - rainfall has decreased and sunshine increased.

tgsnoopy · Unread post by **tgsnoopy** » Fri 05/12/2014 21:10

NZstorm wrote:So the Bay of Plenty arguably could become the sunniest part of NZ. And Auckland becomes sunnier as well.

Umm, isn't Whakatane claiming the title these days (or trying to), so one might argue it's already happening?

NZ Thunderstorm Soc · Fri 05/12/2014 22:18

dunno?

RWood · Unread post by **RWood** » Fri 05/12/2014 23:20

tgsnoopy wrote:
NZstorm wrote:So the Bay of Plenty arguably could become the sunniest part of NZ. And Auckland becomes sunnier as well.
Umm, isn't Whakatane claiming the title these days (or trying to), so one might argue it's already happening?

Whakatane is merely one of many cases where the electronic readings are giving much higher values - by 150 to 400 hrs per annum - than manual equipment in the same locations did. When apples were compared with apples (manual era) Whakatane was clearly lower than Nelson and Blenheim - in 45 years or so of records it won just twice, with Blenheim, Nelson or Motueka taking the rest - apart from a single year for Mt John.

Much lower on the scale, a Balclutha site is topping an older manual one in that region by over 400 hours/year
I could go on ... while exposures in some cases have been improved, there are far too many anomalies to be explained away.

jamie · Unread post by **jamie** » Sat 06/12/2014 02:09

But are the automatic ones consistent between them? If yes then once we have auto across all key sites it shouldn't matter about old method results.

spwill · Unread post by **spwill** » Sat 06/12/2014 08:26

From Niwa website regarding Whakatane sunshine hrs,
https://www.niwa.co.nz/news/whakatane-s ... s-released

NZstorm · Unread post by **NZstorm** » Sat 06/12/2014 08:31

I suspect annual sunshine could drop a little over the South Island due to more upper level cloudiness.

RWood · Unread post by **RWood** » Sat 06/12/2014 10:16

jamie wrote:But are the automatic ones consistent between them? If yes then once we have auto across all key sites it shouldn't matter about old method results.

That's a good question. There have been plenty of issues. I pointed out to Niwa when Queenstown Aero values suddenly dropped dramatically - the instrument had to be replaced. Franz Josef (not renowned for sunshine) has had more than one run of absurdly high values, and currently this has been happening for over a year. A comment from the UK from someone comparing equipment types was that the type used here (Kipp-Zonen is the name I think) could "drift in calibration" readily. Re Whakatane, see my other post.

RWood · Unread post by **RWood** » Sat 06/12/2014 10:22

spwill wrote:From Niwa website regarding Whakatane sunshine hrs,
https://www.niwa.co.nz/news/whakatane-s ... s-released

That was over 5 years ago, and Whakatane "anomalies" have increased since. Last year's tally of more than 300 hours ahead of Nelson and Blenheim is just plain ridiculous. Note also the caveat at the end of NIWA's 2009 report.
And now one has New Plymouth with similar anomalies - both centres' annual totals were over 400 hours more than their old manual averages. Stations further "down the list" (like Franz Josef) don't get noticed because even their inflated values will never "compete".

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