Re: Solar Cycles, Ocean & Polar Vortex Interaction.
- From: Alastair <al@xxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Wed, 1 Dec 2010 01:21:38 -0800 (PST)
On Nov 30, 2:44 pm, Teignmouth <teignmo...@xxxxxxxxx> wrote:
A fasinating read over on TWO by Stephen Wilde regarding the
interaction between Solar Cycles, the Oceans & the Polar Vortex..
Link to the full threadhttp://www.theweatheroutlook.com/twocommunity/default.aspx?g=posts&t=...
Here's are a couple of extracts.
Stephen Wilde
#44 Posted : 29 November 2010 20:54:16
Quote
Rank: Advanced Member
Mid 20th Century cooling spell - Weaker cycle 20 and on average a
negative AO.
Late 20th century warming spell - Strong cycles 21, 22 and 23 and a
very positive AO
Early 21st century warming has stopped or at least slowed and some say
we have cooling - weak cycle 24 and negative AO.
MWP warming period - Strong solar cycles and AO even more positive
than late 20th century with agriculture possible in Greenland.
LIA cooling period - weak solar cycles and AO even more negative than
early 21st century with ships logs recording large storms much more
equatorward than currently.
I don't think the word 'could' is quite up to the task.
The pattern is clear and needs explanation if any climate narrative is
to make sense.
The size of the polar vortex at the surface seems to be very sensitive
to the sun's output one way or another.
However the ocean cycles do skew the timing of the size variations of
the polar vortex because they are not always in phase with the solar
effect.
Thus in the 1930s the polar vortex was pushed poleward by a positive
PDO supplementing the solar effects on the polar vortex before the
full effects of high cycles 17 18 and 19 were felt and the subsequent
30 years of negative PDO delayed the effects of cycles 17 18 and 19 by
offsetting the solar effects on the polar vortex. Only when polar and
ocean effects come together did the more extreme positivity of the AO
develop in the late 20th century.
We now have a quiet sun and 30 years of negative ocean cycles to look
forward to which involves cooling.
The alteration to ocean heat content from more poleward or more
equatorward jets takes time to feed through to the underlying ocean
cycles by slowly and cumulatively altering the balance between El Nino
and La Nina from one 30 year PDO phase to another.
The simultaneous changes to the temperature profile along the
thermohaline circulation have much longer term effects that need not
concern us here.
================================================================================
#45 Posted : 29 November 2010 21:22:42
Gray-Wolf said:
"I'd be very surprised if we saw as much blocking this year (as we saw
last year) or the AO go as neg. as it did last year."
Since the sun has recovered a bit from the solar minimun then yes in
principle that would be correct.
However, remember that ocean cycles can supplement or offset the solar
effect.
So, whilst the very slight increase in solar activity might tend to
suggest a more positive AO than last year with less blocking that
small solar change is likely to be more than offset by the current
strong La Nina.
Thus the current extreme blocking and large deviations in the jet
streams. The La Nina in contracting the tropics is giving the polar
vortex lots of space in which to play around with us.
It will take the next El Nino to tighten things up a bit and in a year
or two the sun will be a little more active so then the AO will go
somewhat more positive.
However it is not going to go as positive as it did in the late 20th
century for a good many years, probably decades and possibly centuries
unless we suddenly get a very high solar cycle. The chances of a very
strong El Nino sending the AO significantly more positive without a
strong solar cycle in support is very low because the last 10 years of
steadily more equatorward jets has begun to reduce ocean heat content
and skew the balance more towards La Nina.
After my recent successes at weather forecasting, I was asked whether
there would be a White Christmas. No doubt if you spend it on top of
Ben Nevis you will not be disappointed, however for most of us that
will not be the case. I am forecasting one of the warmest Christmas
Days on record!
Cheers, Alastair.
.
- References:
- Solar Cycles, Ocean & Polar Vortex Interaction.
- From: Teignmouth
- Solar Cycles, Ocean & Polar Vortex Interaction.
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