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Winter 1962/63....so what caused it?

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STEVE GROOME
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« on: August 21, 2010, 10:00:26 am »

Hi all,

Winter 1962/3 will live in my memory forever,For me personally, there has been nothing to compare since.
I have seen all the surface pressure charts(which are available online)from that winter, and we know HOW it happened but there has been very little theory as to WHY it happened.

I have my own theory as to the WHY,and I think it was a chain of of events that year that would lead us here in the UK to experience our (coldest winter) since 1740,and in some places a very snowy one.

We have had many cold/snowy winters here in the UK,1968/1969 and 1980/81 being two examples, especially here on the edge of the Chilterns in Hertfordshire,more about those winter later.Most times we get two or three weeks of cold weather with a lot of snow in places on initial set-up,and breakdown as the zonal Westerlies take over again.

Considering our Latitude we should get far worse winters than we do. But  we have a vast area of warmer waters in the shape of the  Atlantic,which has been in warm phase for the last 2/3 decades.So to get a cold (sustained) winter we have to shut the door on the prevailing Westerlies.We do get periods of anticyclonic weather which will block,or divert the Depressions coming in from the west but as I said after a while the Zonal Westerlies will usually win out after two or three weeks or less.

Here in the Northern Hemisphere in Winter there is a steep thermal gradient between the Arctic and further south as temperatures fall rapidly.This increases the strength of the cyclonic Polar Vortex,in turn strengthening the Westerly flow across the Atlantic.Without going into too much detail,the Polar Vortex sits over the Arctic  like a giant "Flywheel"put more energy in and it will keep spinning,but if you can slow it down it will lose some of its energy and spin slower,thats the simplified theory.

In reality there are thermo-dynamic mechanisms that can do this.

One such mechanism is a SSW event(Sudden Stratospheric Warming). Major mid-winter Stratospheric sudden warmings occur with a frequency of approx 6 events per decade.There are different types of SSW events but to keep things relatively simple we wont go into detail now.The two types of SSW are Splitting and displacement of the Vortex.The vortex spins at different speeds at different heights.

In late December 1962 the 10-mb circulation pattern over the northern hemisphere consisted of a cold and nearly circumpolar cyclone surrounded by a chain of anticyclonic cells located from about 25 to 45N.One of these more active anticyclones retrogressed from the mid-Atlantic to position over the central United States. In the northern part of this high temperatures increased over the Great Lakes and northern United States.This relatively minor warming ended in the first days of January with the collapse of the anticyclone over the US.

The Polar vortex was at its most mature stage by January 8th with central temperatures of -85C and a nearly curcumpolar band of strong westerlies,with winds at 10-mb exceeding 200 kt extended from middle latitudes northward to the Arctic.

Details of the major stratospheric warming event that I think set-up the winter 1962/63 in Part Two  to follow

Steve


PART TWO:


Perhaps the most striking thing about the circulation during this period was the retrogression of  low latitude anticyclones.

A large scale alteration in the cyclonic vortex circulation pattern appeared around the January 14th when the Polar cyclone began to elongate towards North America and Eurasia.As a result of this evolution the circumpolar vortex became that of a nearly symmetrical bipolar,or wave number two pattern.By January 18th prominent features of the circulation pattern was a rapidly building Atlantic Anticyclone and a more diffuse anticyclonic system stretching across Asia from the Western Paciffic ocean.

At the same time anomalously high temperatures were being advected into Southeastern Canada,although warm advection was not the only thing happening.Data from Goose Bay,Laborador show that temperatures at both 50- and 10-mb began an extended rise around Jan 13th. Examination of the daily 10-mb charts shows that there was a warming trend in general over most of Eastern North America,with the most notable changes taking place in the strong Southerly flow between the Atlantic Anticyclone and the deep polar trough extending across Western Canada.

With radical changes in the thermal field over North America from Jan 18th-23rd,there was additional intensification of the Atlantic anticyclone.The northwestward movement of the intensifying warm air and accompanying sharp rise in the 10-mb surface were strongly affecting the area around the North Pole.As a consequence the polar cyclone acquired two distinct centers which began moving southwestward over North America and Eurasia respectively.

A survey of available data reported that the highest temperature during the intense warming phase was -2 C measured at 12-mb. 6 days earlier when the warming began the temperature measured at the same station,and the same pressure surface was -78C.Temperature inversions like this were reported from many stations to the West of the axis of warm air.The warming progressed downwards to most levels,and a sharp decrease in wind speeds was reported at most levels.As a result of lateral spreading of warm air across North America after Jan 8th a complete reversal of the temperature gradient had taken place at 10-mb surface by Jan 27th.

The temperature rise of 55C over the North Pole during the period Jan 22nd-27th reflected in a height increase of 2400 meters. MOST IMPORTANTLY, the only remaining indications of the wintertime polar vortex were two deteriorating cyclones moving rapidly southwestwards over Europe and the extreme eastern Pacific Ocean.

The wintertime polar vortex had been destroyed.


Steve

« Last Edit: August 21, 2010, 05:46:56 pm by STEVE GROOME » Report Spam   Logged

martinastro
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« Reply #1 on: August 21, 2010, 04:13:20 pm »

A fascinating read Steve, I've certainly learned something new today that's for sure, going to have read through this again to take it all in. That extreme Winter must have made a significant impression upon you. I look forward to reading part 2  Smiley
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markt
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« Reply #2 on: August 22, 2010, 07:28:12 pm »

Thats a great read Steve, thanks for posting! Smiley

Like Martin i've certainly learnt something new and will no doubt have a good couple of  re-reads as I ponder it.  This winter was a good decade before my time i'm afraid, so I have no personal recollection of it.  But it is interesting to read about the mechanisms and causes behind it and use these to reflect and compare to other winters.  It's normally about this time of year, as the uk summer has all but faded out that I start pondering the forthcoming winter in the UK.  Interesting looking back at the threads on this forum we'd got a pretty accurate picture of what it was going to do by october time.  I won't hog your thread and start that discussion here, but i'm certain before long a 'winter 2010/11' thread will appear.

Again, many thanks Steve.

Regards, Mark Smiley
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STEVE GROOME
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« Reply #3 on: August 22, 2010, 10:43:23 pm »

Hi Mark,

thanks for your comments,glad your found it interesting.

I must admit my thoughts also turn to what the coming winter will bring around this time.

I think the last two winters have been warnings for winters to come as we get closer to 2012, and beyond.
The Sun is acting very strangely,and has been for a long time now and has been going through,and still is in its quietest period for decades.By the time we reach the next solor minimum the AMO(Atlantic multidecadal oscillation) will be going into its cold phase.With a cold PDO already started,we could start to see more and more cold winters with the distinct possibilty of another very severe winter.

Steve
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markt
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« Reply #4 on: August 23, 2010, 07:17:58 am »

I think the last two winters have been warnings for winters to come as we get closer to 2012, and beyond.  The Sun is acting very strangely,and has been for a long time now and has been going through,and still is in its quietest period for decades.By the time we reach the next solor minimum the AMO(Atlantic multidecadal oscillation) will be going into its cold phase.With a cold PDO already started,we could start to see more and more cold winters with the distinct possibilty of another very severe winter.

Yes, i've read similar things before about this.  Personally I like a good old cold winter (though not everyone may share my views on this!), I hate the grey, damp and mild winters we have had of late...
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« Reply #5 on: August 24, 2010, 01:16:57 pm »

Quote
I hate the grey, damp and mild winters we have had of late...
Me too, though last winter was not bad at all - far better than this grey, damp & mild summer ....
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martinastro
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« Reply #6 on: August 26, 2010, 01:12:48 am »

I'm definitely up for another severe/extreme Winter, if I get to see lakes and rivers freezing over for the second year in a row I will be really impressed, throw in another epic blizzard and a white Christmas Eve/Day then I couldn't imagine a better way to experience Winter  Smiley
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