Record Sun for Invercargill January 2008

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janewaystv
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Record Sun for Invercargill January 2008

Unread post by janewaystv »

To end 29th Jan (yesterday), 270 hours has been recorded at the airport, easily beating the old Jan. record of 254 hrs set in 1999, not only that, its the sunniest ever of any month (previous highest was also that of Jan. 1999) since Aero records began in 1932.
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Re: Record Sun for Invercargill January 2008

Unread post by RWood »

Yes, a remarkable total. Even if the EWS is lower it should surpass the 250s.
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Re: Record Sun for Invercargill January 2008

Unread post by janewaystv »

Just looked at NIWA Jan 08 climate summary - 287 hours - quite a big step up from the prev. record of 254 hrs, average is 185 hrs so an increase of 102 hours, last year had 199 hrs, summer sun TD is 527 hrs. (Current record is 656 hrs 1955/1956).
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Re: Record Sun for Invercargill January 2008

Unread post by RWood »

Both the In'gill and Dunedin values would seem scarcely credible, but in fact they reinforce each other. 150% months anywhere in the NZ sunshine history are very rare.
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Re: Record Sun for Invercargill January 2008

Unread post by janewaystv »

Can you give me any past occasions of when this has happened?
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Re: Record Sun for Invercargill January 2008

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Ohakune, July 1973 - 170 hrs, average about 103, 166%
Taumarunui, July 1973 - 149 hrs, average 89, 167%

Levin, Sept 1958, 240 hrs, average 140, 171%

There would be some others but I would have to run several reports to get them.
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Re: Record Sun for Invercargill January 2008

Unread post by janewaystv »

Invercargill's run of warm weather has come to an end judging by comments from my brother, he said its been quite cool this week with plenty of strong W winds, but rain has been lacking, only a few light showers around, but should start warming up again soon. Only 22mm MTD has fallen at the airport.
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Re: Record Sun for Invercargill January 2008

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Here's an updated calculation after December's numbers (240 manual, 223 EWS):

Ingill, 1932-2007 185.6 163.1 141.2 107.3 87.3 73.2 93.6 120.9 139.2 163.6 175.5 189.1 1639.6
EWS calc, 1932-2007 174.1 147.8 137.4 102.6 86.3 75.4 96.0 120.7 137.8 154.0 154.8 173.2 1560.3
(based on ratios so far)

Ingill, 1978-2007 182.5 164.7 140.3 115.0 84.3 77.7 95.4 120.0 139.2 167.7 179.2 187.4 1653.4
EWS calc, 1978-2007 171.2 149.2 136.6 110.0 83.3 80.1 97.8 119.8 137.8 157.8 158.1 171.7 1573.4
(based on ratios so far)
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Re: Record Sun for Invercargill January 2008

Unread post by janewaystv »

Didnt EWS readings start in 1996?
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Re: Record Sun for Invercargill January 2008

Unread post by RWood »

Actually in 2003. The EWS averages are a calculation for hypothetical means based on the ratios so far (I sent a November version with the details earlier). Of course with only a few years of comparison it would take a while to settle, though the ratios are reasonably consistent.
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Re: Record Sun for Invercargill January 2008

Unread post by janewaystv »

IVC Aero had 188 hrs for Feb, 100 hours less than Jan but still above average (163 hrs). Summer total of 715hrs highest on record & beating previous high of 656 hrs set in the Summer 1955/1956.
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Re: Record Sun for Invercargill January 2008

Unread post by RWood »

I'll get the EWS figures later - think they would probably be a little above that 656 value.
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Re: Record Sun for Invercargill January 2008

Unread post by janewaystv »

I see http://www.stuff.co.nz has now returned to its routine of updating it's sunshine total for IVC daily - ending yesterday - currently 118 hrs. I hear it was 27oC yesterday & Tuesday, however rain and a strong cold SW change expected tomorrow afternoon but not expected to last with fine conditions returning on Saturday.
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Re: Record Sun for Invercargill January 2008

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Met a guy from Tuatapere a few days back. Said he wasn't used to the levels of warmth experienced this season - I suggested the extra sun would have enhanced the effect further.
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Re: Record Sun for Invercargill January 2008

Unread post by janewaystv »

March 2008 saw IVC Aero recording 182.9hrs of sun - 41 hrs more on the average & the sunniest March in 61 years & is the 2nd sunniest March on record after 1947's 207 hrs. Yearly total now at 658hrs & with 9 more months to go...yearly average is 1642hrs, of course the "cloudy" part of the year is yet to descend...
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Re: Record Sun for Invercargill January 2008

Unread post by RWood »

Well, at least the westerly pattern may return to some degree.
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Re: Record Sun for Invercargill January 2008

Unread post by janewaystv »

Might be the case this month (April) :-k

Since January 2006 - only 2 months have recorded below average sunshine (December 2006 by 17 hours & April 2007 by 10 hours), so this is the 11th consecutive month to have above average sunshine.
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Re: Record Sun for Invercargill January 2008

Unread post by RWood »

Yes, it's quite a run. If the next more westerly phases don't halt it I would get suspicious - but other readings in the South seem to corroborate it well at present.
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Re: Record Sun for Invercargill January 2008

Unread post by sthguy »

Invercargill
so this is the 11th consecutive month to have above average sunshine.

Sun % values rounded, 'westerlies' mean westerly quarter i.e. NW - W - SW

March 2007: Westerlies dominant for over two weeks, sun 107% of normal
April: Westerlies dominant up to 17th, then little wind. Sun 92% of normal
May: Westerlies very dominant with 6 days of gale. Sun 142% of normal
June: Westerlies very dominant with another 6 days of gale. Sun 132% of normal
July: Westerlies dissappeared for much of the month. Sun 115% of normal
Aug: Westerlies very dominant but not strong [no gales] Sun 111% of normal
Sept: Westerlies very dominant but much weaker than normal. Sun 115%
Oct: Westerlies very dominant and strong again with 6 days of gale. Sun 116% normal
Nov: Westerlies very very dominant {Every day of the month!!} 2 days of gale. Sun 119% of normal
Dec: Westerlies very dominant but much weaker. Sun 127%
Jan 2008: Westerlies very dominant in the first 3 weeks with 2 days of gale. Sun 155%
Feb: Sporadic westerlies only. Sun 116% of normal
March: Westerlies very dominant 4th - 24th but weak-ish with only 1 day of gale. Sun 130% normal.

It's worth noting that 4 of those months recorded more rain - substantially more - than normal yet still recorded higher than normal sunshine {March 157% June 176% Aug 144% Oct 153%}

Conclusion. More frequent and stronger westerly quarter wind flows do not go hand in hand with low sunshine totals in the south. It is likely that the position and frequency of cloudy anticycones may be the driving influence. Position, in the sense that low level winds flows in the south be onshore {more cloud} or offshore {less cloud} below the inversion layer present in such highs.

Anticyclonic gloom, anyone?
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Re: Record Sun for Invercargill January 2008

Unread post by RWood »

By "westerly" (or its absence) I'm referring to the general wind anomaly regime over NZ, rather than just Invercargill, particularly with reference to the recent La Nina period. With older records - say those from about 1991 and earlier - the cloudier months in In'gill have often been those with a bigger dominance of W or SW, particularly the latter. There are of course other scenarios associated with cloudier months. The question yet to be answered is whether the increase in sunshine since about the mid-90s in a variety of regimes is entirely climatological, or whether it is partly an artifact of measurement. The sunshine recording network is fairly sparse, which doesn't help. Readings in Dunedin from about the mid-90s (with a break in recording of several years however) have also been higher than in the previous decades (back to the early 50s).
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sthguy
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Re: Record Sun for Invercargill January 2008

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More westerlies? ! I don't think the southern folk would thank you for that. Fairly hard to squeeze more in in many of those months in the last year.... :(

Selected at random, 1989

Month/%rain/%sun/gales
Jan 61% 112%
Feb 163% 93%
Mar 213% 97%
Apr 89% 114% 4
May 59% 119% 4
Jun 134% 110%
Jul 68% 112%
Aug 23% 141%
Sep 13% 124%
Oct 64% 108% 1
Nov 105% 107% 2
Dec 162% 117% 1

Aug/Sept probably the lowest ever two month rainfall period.
1989 had 12 days with gale winds, 2007 had 26 days.
With older records - say those from about 1991 and earlier - the cloudier months in In'gill have often been those with a bigger dominance of W or SW, particularly the latter
Can you offer examples? The more I look the less obvious any connection is between sun totals and dominance of westerly flow. Indeed the SW flow is often sunny {between convective showers!} because of the frequently unstable nature of airflow from that direction.
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Re: Record Sun for Invercargill January 2008

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I am reviewing examples from printed records which date back to 1955. As I said, am excluding stuff after about 1991 because of the upward shift in the "baseline" for sun. Until I get back with concrete examples I will note the following:

1989 was a year dominated by a strong La Nina and a comparative absence of westerlies. It was also Invercargill's sunniest year to date. The examples I quote (selected from many, will just quote the stronger cases) will be in one of these categories of New Zealand flow anomaly: S+SW, SW, SW+W, westerly quarter, anticyclonic, anticyclonic plus NE, E or SE. While there are a number of contributing factors to cloudier months - of which one is fairly slack gradients with central or northern anticyclonic centres, some troughs in the south and a bit of light W/SW/NW in the south (especially in winter) the examples will show typical anomalies in those earlier "westerly" groups with sun deficit, rainfall excess or showery weather excess, plus of course cooler temps. if the SW anomaly is the main factor. By contrast the significantly sunny months in the period I'm talking of are overwhelmingly in the latter categories (anticyclonic.....).

As it is a brilliantly sunny day here I am going to take advantage of that now.
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Re: Record Sun for Invercargill January 2008

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Here are some cases to consider. Note the following:

I have no summary reports prior to 1955 (“Rainfan” can probably give a few examples for earlier years). The period covered is 1955-1991; Cliflo summaries have the sunshine totals for 1992-2005 flagged as suspect at present, and it is probably too early to consider data newer than that. The following was thrown together fairly quickly, and I’m not guaranteeing that there are no errors in it. I selected months that were either significantly sunnier or cloudier than average by quickly eyeballing some graphs. The ones given below fall into one of a few well-defined patterns. Cases (like 12/1975) with more complicated patterns were not included. Offhand, I noticed few sunny months that did not have some kind of reduction in westerly influence (if any at all). I have not analysed months that had near-normal sunshine, as this would be much too time-consuming.


Group 1: Anticyclonic anomaly over NZ, or at least relatively in the south or central-south, general reduction in frequency and/or strength of W & SW over NZ, also usually some E/NE anomaly (except where noted). Invercargill values: dry or very dry except where noted, sunnier or much sunnier, average or above average temperatures.

12/1955, 9/1957, 10/1958, 1/1959, 4/1960, 9/1960, 2/1964, 8/1970, 2/1971, 4/1971, 6/1973, 11/1974, 12/1974, 11/1987, 8/1989, 9/1989, 11/1960 (this last had near average rainfall)

1/1956 (exceptional warmth, record sun, also some periods of very hot N/NW)

Group 2: Average to higher than average pressures in the south (sometimes also in the rest of the country), less W & SW except where noted, often extra E/SE/S. Invercargill values: dry in most cases, sunnier or much sunnier, average or below average temperatures.

7/1973, 1/1974, 4/1982
5/1956, 10/1959, 8/1961, 8/1966, 6/1974, 8/1981, 7/1991 (cold, most drier)
2/1972, 10/1985 (some extra SW and S, strongly anticyclonic)

Group 3: Average to higher than average pressures in northern and/or central districts, some combination of excess of SW, W or NW in the south. Invercargill values: Mostly wetter than average, cloudier or much cloudier, temperature departure depending on the westerly combination, but mainly near average.

9/1956 (record low sun till 1980)
3/1969, 10/1969, 5/1973, 1/1982, 8/1985, 7/1987

Group 4: Average or lower than average pressures over NZ, marked excess of SW flows (usually both strength and frequency). Invercargill values: Wetter than average except where noted, cloudier or much cloudier, temperatures below average except where noted.

4/1958 (exceptionally wet, also cold and very cloudy)
2/1965, 4/1965, 12/1965, 7/1976, 11/1980, 5/1983, 2/1987 (record low sun
In the last case)
5/1967, 9/1981 (average temps)
4/1972 – 6/1972 inclusive (large SW anomalies, extremely wet and cloudy, 4/1972 relatively mild)
5/1988 (large number of hail days)
5/1991 (lighter flows but very high SW frequency, very cloudy, 28 rain days)

Group 5: Generally lower than average pressures over NZ, unsettled westerly conditions with cyclonic NW, W or SW flows common, Invercargill anomalies mainly of NW & W, sometimes also SW. Invercargill values: Wetter than average, cloudier or much cloudier, temperatures variable depending on anomaly balance, mostly average or below.

10/1957, 11/1957, 1/1964, 8/1964, 10/1968, 4/1975, 1/1977, 9/1977 (some S
surplus), 9/1980 (record low sun), 1/1983, 3/1983, 9/1988, 1/1991.
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Re: Record Sun for Invercargill January 2008

Unread post by sthguy »

I don't think it is wise to use the New Zealand flow anomaly as a proxy for wind conditions in a specific location so far south. For example, to do so in the present strong la nina conditions would lead one to conclude the prevailing westerly flow should be much weaker than normal in the deep south with a higher incidence of winds from the NE quarter. Measured daily wind patterns have actually been dominantly westerly for many months, and quite strong at times, with only relatively short periods of lighter and variable wind directions.

Nevertheless those results are interesting. Intensive study would need to look at sunshine in relation to the specific frequency of winds on a daily basis. This would need to include all months, not just those with strongly positive or negative sunshine anomolies. Selecting the cases that most strongly back an argument make a point but doesn't lead to a definitive result. There would need to be a scoreboard. I suggest this scoreboard may be as muddled as the combinations of wind and sun are.
I have a real job and will not be doing this =D>

Its also worth says that we are talking about small things rather than large scale synoptics. Eg on an average southern sunshine month, an extra 30 mins a day sun will result in an 11% higher than average end of month total...each day thats only 1 good Cb less obscuring the sun, one decent gap of a few square km in a sheet of stratocumulus.....
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Re: Record Sun for Invercargill January 2008

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My original point concerned a return to typical westerly conditions in NZ terms. You are trying to conclude too much on the basis of somewhat doubtful sunshine data. An "extra 30 minutes a day" is a very significant amount, and always has been for all sites in the whole NZ climatology. Not a small thing at all. Also, it's not adequate to merely talk about your particular incidence of westerlies - it's the differences from your averages that count. If you want to construct a case that there have been a "lot" of westerlies even in the La Nina phases, you are going to have to come up with some hard data from a lengthy set of daily obs. - feel free. Judging by your comment, it won't happen. At this stage you certainly haven't convinced me that the situation is "muddled".

You may have a "real job" - my time is also valuable. I don't intend to expend more of it trying to convince you. I will merely add on a personal note that I lived in Invercargill for quite a number of years and had no difficulty discriminating between periods of very dominant westerlies and those where they were far less so. Even some degree of increase in westerly flow in the later parts of last century is not going to push things to the point you are implying.
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