Stratosphere Temperature Watch 2014/2015

[chionomaniac]

So summer will be good then? There is a final warming every spring, is there not? But the strength of that warming determines whether or not we see HLB over the arctic during summer? HLB over the arctic during summer is responsible for the rapid melt seen over the arctic during the period 2007-2012?

In short no. Once the final warming is out of the way, the polar stratosphere is very stable during the summer months with weak easterlies maintained until late August. Contrast this with the tropospheric polar vortex which stays (mean) westerly all year around with the lowest mean westerly winds at 150hPa experienced during June and July.

[Interitus]

In short no. Once the final warming is out of the way, the polar stratosphere is very stable during the summer months with weak easterlies maintained until late August. Contrast this with the tropospheric polar vortex which stays (mean) westerly all year around with the lowest mean westerly winds at 150hPa experienced during June and July.

 

There may be slightly more to it than this with features such as Frozen-in Anticyclones (FrIACs) which originate at lower latitudes and become 'stuck' over the polar region with the natural anticyclonic tendency during summer, and the displaced remnant winter vortex fragments persisting further south. These features have been studied with effects on ozone in particular and the signature of FrIACs can sometimes be seen to persist throughout the summer.

Effects on the troposphere are not so clear and appear little researched though there are a number of papers which examine the tropospheric effects of the timing and nature of the final warming itself.

In the northern hemisphere this has largely been viewed as springtime effects, for example of Arctic geopotential rise (which theoretically could have an impact on early ice melt pool formation which has been suggested as a critical factor in overall summer ice melt) and changes to storm tracks such as in the Atlantic-Europe area.

In the southern hemisphere a general latening of final warmings since the 1960s, with possible links to ozone depletion, have been associated with longer term climatological changes in Antarctic circulation which may play a part in recent high sea ice extents.

Edited March 22, 2015 by Interitus

[summer blizzard]

Looks like the final warming is indeed occuring as forecast..

 

 

 

[Cloud 10]

Looks like the final warming is indeed occuring as forecast..

 

 

 

 

 

Looks like the Polar Vortex is entering self-destruct mode at all levels over the next week or so,which appears to be a fast response to the final warming.

 

ecm day 5..  ecm day 8..

 

[picog]

Looks like the Polar Vortex is entering self-destruct mode at all levels over the next week or so,which appears to be a fast response to the final warming.

 

ecm day 5..EDH1-120.gif  ecm day 8..EDH1-192.gif

 

ecmwfzm_u_f192.gif

RIP polar vortex 2014-2015!

[karyo]

Good to see some updates lately

[Cloud 10]

Quite a dramatic final warming of the stratosphere this year shown nicely when looking at the temperature and wind anomalies for the end of March.

 

temps...  wind...

 

 

Just look at that rise in temperature at 30 mb over the pole!

 

[skatefan]

Quite a dramatic final warming of the stratosphere this year shown nicely when looking at the temperature and wind anomalies for the end of March.

 

temps...time_pres_TEMP_ANOM_JFM_NH_2015.gif  wind...time_pres_UGRD_ANOM_JFM_NH_2015.gif

 

 

Just look at that rise in temperature at 30 mb over the pole!

 

It seems indeed quite dramatic. Remnants of the polar vortex are driven far into Russia and appear to reluctantly give way. A late Spring seems to be occuring. Symptomatically for this winter: a not too strong Vortex that is stronger than it appears...?

 

 

[MattH]

A somewhat 'out of season' post...

 

However, just been looking at this April and just how dry and generally anticyclonic it has been and I can't help but think, or at least put 2 and 2 together, to come to the conclusion that the quite abrupt end to the stratospheric vortex this year has indeed helped to produce a generally more blocked pattern into April. Clearly April and May can be months of extremes and can be two very difficult months to forecast given the transition away from winter and into spring. However, the reluctance for any unsettled conditions to become established this month is quite noteworthy and again many areas are experiencing a particularly dry month and again a quick reanalysis through 1st April to present day shows a particularly anticyclonic month but of which is likely to come to a rather abrupt end later this week and beyond.

 

Be interesting to see where we go from here. April update of the EC Seasonal and EUROSIP seasonal models, both of which did a decent job on winter, produce a rather interesting and unfavourable pattern for a good summer in that a -ve NAO pattern is signaled for the summer months with a +ve pressure anom to the north and north-west of the UK, which, overall, will signal a generally blocked regime but with the block being in completely the wrong place. There is little evidence that supports a more pronounced Azores high this summer and again the pattern is for more northern blocking, which, as we found out a few years ago, is not a good setup for summer!

 

Time will tell as ever...see you all in October.

 

Regards, Matt.

[sebastiaan1973]

I wonder what the impact of the so called super El Nino will be on the stratosphere. Interesting times ahead.

[chionomaniac]

It will be interesting when the Autumn appears to see how the tropical stratosphere responds and how this is passed polewards. Perhaps we will have another year when the comparable analogue years are completely different to what winter actually delivers!

[Frozen Britain]

It will be interesting when the Autumn appears to see how the tropical stratosphere responds and how this is passed polewards. Perhaps we will have another year when the comparable analogue years are completely different to what winter actually delivers!

Are there any comparable analogue years which might give an indication? How do you expect it to respond? Or would you rather sit back and watch? Don't you need a cold tropical stratosphere for stratospheric warmth?

[Recretos]

Judging by the correlations, and considering that the ENSO region is strongly positive, it looks interesting, tho the factor is not that strong.

[feb1991blizzard]

Judging by the correlations, and considering that the ENSO region is strongly positive, it looks interesting, tho the factor is not that strong.

 

Just hypothesizing for a moment, it looks like a strong EL NINO event is likely this Autumn winter, if this were to happen, what would the Stratospheric analogues look like for winter then, still baring in mind that +PDO is still looking likely from what I understand?

[Recretos]

Well, so far, the strat seems to be doing the opposite of what is supposed to be the main signal from a positive ENSO3.4.

[KyleHenry]

http://www.atmos-chem-phys.net/15/8695/2015/acp-15-8695-2015.html

Paper more akin to 2017 onwards.

[Recretos]

Foundations of the new polar vortex are starting to appear over the pole in the FI.

Edited August 12, 2015 by Recretos

[Dorsetbred]

Well, so far, the strat seems to be doing the opposite of what is supposed to be the main signal from a positive ENSO3.4.

Any ideas why that might be?

[Methuselah]

The qbo is now 7.45.

And what does that mean?

[Recretos]

Any ideas why that might be?

Looking at further correlations, the positive AMO signal seems to be still present.

[feb1991blizzard]

Yes everything lately seems to be doing the opposite to the analogues in winter doesn't it.

Edited August 24, 2015 by feb1991blizzard

[Recretos]

Yes everything lately seems to be doing the opposite to the analogues in winter doesn't it.

 

Not sure if this comment is legit or sarcastic.

[sebastiaan1973]

http://onlinelibrary.wiley.com/doi/10.1002/2014JD022848/pdf

Abstract This paper examines the possible linkage between the recent reduction in Arctic sea-ice extent

and the wintertime Arctic Oscillation (AO)/North Atlantic Oscillation (NAO). Observational analyses using the

ERA interim reanalysis and merged Hadley/Optimum Interpolation Sea Surface Temperature data reveal that a

reduced (increased) sea-ice area in November leads to more negative (positive) phases of the AO and NAO

in early and late winter, respectively. We simulate the atmospheric response to observed sea-ice anomalies

using a high-top atmospheric general circulation model (AGCM for Earth Simulator, AFES version 4.1). The

results from the simulation reveal that the recent Arctic sea-ice reduction results in cold winters in mid-latitude

continental regions, which are linked to an anomalous circulation pattern similar to the negative phase of

AO/NAO with an increased frequency of large negative AO events by a factor of over two. Associated with this

negative AO/NAO phase, cold air advection from the Arctic to the mid-latitudes increases. We found that the

stationary Rossby wave response to the sea-ice reduction in the Barents Sea region induces this anomalous

circulation. We also found a positive feedback mechanismresulting from the anomalous meridional circulation

that cools the mid-latitudes and warms the Arctic, which adds an extra heating to the Arctic air column

equivalent to about 60% of the direct surface heat release from the sea-ice reduction. The results from this

high-top model experiment also suggested a critical role of the stratosphere in deepening the tropospheric

annular mode and modulation of the NAO in mid to late winter through stratosphere-troposphere coupling.

[Recretos]

The band of brothers is forecasting the further slow establishment of the re-emerging polar vortex. And now we have the upgraded GEFS, which is now configuration-wise the best free ensemble forecasting system for the stratosphere and otherwise.

 

  

[snowking]

I personally can't wait for another season of Andrej's wonderful graphics, especially given the GEFS upgrades in the interim.

It's the time of year that I generally start to come out of hibernation again so I'm hoping to start taking a look at a few potential analogue years in the coming weeks when I can find some time.

Here's to another rollercoaster ride

SK