Stratosphere Temperature Watch 2014/2015

[chionomaniac]

As winter has gone on I have found myself disagreeing with som aspects of this blog and just had a quick breeze through and find myself disagreeing again. There was a significant strat warming but no SSW for a start....

[Duane S.]

As winter has gone on I have found myself disagreeing with som aspects of this blog and just had a quick breeze through and find myself disagreeing again. There was a significant strat warming but no SSW for a start....

He does emphasise it was a minor SSW though, which by WMO definition, it was.

[karyo]

As winter has gone on I have found myself disagreeing with som aspects of this blog and just had a quick breeze through and find myself disagreeing again. There was a significant strat warming but no SSW for a start....

According to the blog, they expect to see the effects of the warming continuing throughout February with a -AO.

What do you think?

[Nouska]

As winter has gone on I have found myself disagreeing with som aspects of this blog and just had a quick breeze through and find myself disagreeing again. There was a significant strat warming but no SSW for a start....

 

There seems to be a lot of confusion among the professionals on just what the terminology indicates. This article from the Danish Met Institute has also classed the warming as a SSW.

 

 

Weather in Denmark can come from any direction. This time it is the rather unusual 'from above'.

There are frequently very cold stratospheric winter in northern latitudes. Sometimes we observe, however, a rapid and strong heating - a so-called 'sudden stratospheric warming'. The stratosphere is that portion of the atmosphere which lies between about 10 and 50 kilometers above the earth's surface.

"A beautiful example of a sudden stratospheric warming has just taken place," explains senior researcher at DMI Bo Christiansen.

 

Google translated version.

 

https://translate.google.com/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.dmi.dk%2Fnyheder%2Farkiv%2Fnyheder-2015%2F01%2Fforaar-i-stratosfaeren-truer-danmark-med-vinter%2F&edit-text=

[chionomaniac]

There seems to be a lot of confusion among the professionals on just what the terminology indicates. This article from the Danish Met Institute has also classed the warming as a SSW.

 

 

Google translated version.

 

https://translate.google.com/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.dmi.dk%2Fnyheder%2Farkiv%2Fnyheder-2015%2F01%2Fforaar-i-stratosfaeren-truer-danmark-med-vinter%2F&edit-text=

The sooner that it is clarified the better, and I can't wait for the conclusions of the working body. I have not seen a scientist on the strat email list or working body describe the event as a SSW.

 

I have in my own mind exactly what a SSW is - that is reversal of mean zonal winds at 60ºN and 10 hPa ( with a reversal of the usual temp gradient towards the pole). Anything else is a warming of the strat - I don't like the term minor either because other warmings can be quite significant. For the AER blog to use the term SSW throughout their blog with only informing us that it was a minor one towards the end is misleading in my opinion. They should have stated right at the beginning, that even though that the recent warming may only be classified as minor, it was/will be significant enough to have significant troposheric effects. Now that I would be happy with.

 

 

 

Sometimes I wish that I could re classify the whole structure of strat warmings and events because I have a clear cut idea of what that classification should show.

[Crocodile23]

He does emphasise it was a minor SSW though, which by WMO definition, it was.

 

Can you give the link that contains the WMO definition?

Thanks.

 

[Relativistic]

That section of the paper doesn't describe a 'bounce-back' of zonal flow as measured at a constant latitude eg 60°N.

It describes wave-breaking and to understand it take a look at geostrophic or gradient flow. As the zonal wind is decelerated the flow becomes unbalanced allowing the pressure force to cause meridional flow towards the pole. As it moves northwards the flow is accelerated by the Coriolis force, becomes more westerly again and the zonal flow is re-established at a higher latitude (assisted also by temperature changes). This is the balancing of geostrophic flow and to imagine it more simply it is the anticyclonic flow like round the northern side (northern hemisphere) of an area of high pressure.

Then they describe the meridional flow towards the pole causing sinking and adiabatic warming of air and in very basic terms this is what causes the sudden warming. What is important to remember is that the Eulerian zonal and meridional coordinates only consider two dimensions. Whilst there are these components of the wind following geopotential height contours for example, stratospheric flow over short time-scales is adiabatic and has a vertical component as it follows heights of equal potential temperature up and down. This is isentropic flow, brief description - http://www.cpc.ncep.noaa.gov/products/stratosphere/theta/theta_info.shtml

More detailed - http://vortex.nsstc.uah.edu/data/tmurphy/Teaching/ATS452_SynopticMeteorology/Lecture/04152013_Isentropic_3.pdf

 

Although the second link uses an example from the troposphere it stresses the following -

 

Important point:

 

Air DOES NOT follow the pressure surfaces (constant height charts we normally use)

 

Can not say what happened will just move on to another point on that same map

 

The air at that point will not be at that pressure surface for any length of time… instead traveling up and down isentropes to different pressure surfaces

 

This consideration is implicit to a Lagrangian approach compared to the fixed coordinate Eulerian view.

 

Thanks, another informative reply

[bluearmy]

Yesterday's Berlin data seems to show a wave 1 increase shifting the core of the upper/mid vortex well into Siberia. a large N American block.

The 00z run looks similar if not more pronounced. (And more notably, gfs op sees it the same way)

The zonal flow having picked up retreats back to low levels as soon as this wave 1 drifts down from atop.

I'm sure that ed and Andrew will put some meat on these bones but a downwelling of the pattern into the trop would be most welcome for coldies. No doubt, a sudden unexpected wave 2 will appear to split and leave a Greenland daughter! (That was irony btw)

Edited January 17, 2015 by bluearmy

[sebastiaan1973]

• The downward propagation of negative AO conditions in the stratosphere should begin to influence the tropospheric circulation in about a week. Therefore, we anticipate positive AO conditions to trend more negative the second half of January. This will promote more high latitude blocking and colder temperatures hemispherically for the remainder of the month.  The biggest change should be felt across northern Eurasia including Europe, where temperatures should turn significantly colder from what has been observed so far this month.
• Prospects for a negative AO remain fairly high into February given the recent and ongoing weakening of the stratospheric polar vortex, though some uncertainty on timing and the eventual strength of the negative AO state still remains.

Typically following a SSW, the AO turns more negative in the lower stratosphere and eventually throughout the troposphere within 2 weeks. The negative phase of the tropospheric AO is then favored for 1-2 months following a SSW.  Though the warming is only defined as a minor SSW based on the WMO definition of SSWs, the SSW did result in a daily-record warm temperature in the stratospheric polar cap at 10 hPa and thus is a significant event in the stratosphere. The operational models predict that the polar vortex will remain perturbed in the near-term with recovery possible during this period.  Therefore, we expect a negative bias in the near-surface AO, which should lead to increased frequency of high altitude blocking and cold temperatures across the Northern Hemisphere continents this period.

One caveat in this long-term AO forecast involves the current hemispheric circulation pattern. So far this winter, deep low pressure in the Barents-Kara seas has persisted, and models have had a very difficult time predicting its evolution. This feature is more associated with a positive AO/NAO than a negative AO. Hence, should this feature persist even longer, the transition to the negative phase of the near-surface AO would be difficult (it destructively interferes with a canonical negative AO circulation pattern).  The models once again are predicting for the polar low in the Barents Kara seas to be absorbed into polar lows in the more climatologically favored regions of Eastern Siberia and Hudson Bay (Figure 5).  We have seen this movie before with the Barents-Kara seas polar low only to return.  However the ongoing SSW favors a change in the pattern more so going forward than has been observed so far this winter.

Longer Term

30–day

Based on the SSW in early January, we continue to favor the negative state of the near-surface AO into middle and the end of February. This would increase the chances for more cold air outbreaks across northern Eurasia including Europe, and Central and Eastern North America during February. We have included our seasonal forecast for Northern Hemisphere temperature anomalies for January, February and March 2015 (Figure 6) that was issued in early December.  We continue to favor the overall cold forecast as averaged for the season, though observed temperature anomalies can deviate regionally and temporally through the season (e.g., the anticipated cold spell coming to Europe following a seasonable to seasonably mild December and early January).

 

From Cohen's blog http://www.aer.com/science-research/climate-weather/arctic-oscillation

The zonal flow having picked up retreats back to low levels as soon as this wave 1 drifts down from atop.

 

 

I really try to understand what you mean with this? Can you explain a little bit more? Thanks!

Edited January 17, 2015 by sebastiaan1973

[bluearmy]

I really try to understand what you mean with this? Can you explain a little bit more? Thanks!</p>

.

comprendez?

Edited January 17, 2015 by bluearmy

[feb1991blizzard]

Yesterday's Berlin data seems to show a wave 1 increase shifting the core of the upper/mid vortex well into Siberia. a large N American block.

The 00z run looks similar if not more pronounced. (And more notably, gfs op sees it the same way)

The zonal flow having picked up retreats back to low levels as soon as this wave 1 drifts down from atop.

I'm sure that ed and Andrew will put some meat on these bones but a downwelling of the pattern into the trop would be most welcome for coldies. No doubt, a sudden unexpected wave 2 will appear to split and leave a Greenland daughter! (That was irony btw)

 

Are those charts up to date BA?, they aren't updating on my computer, but it could be my computer because de bilt among other things I have struggled with lately.

[lorenzo]

The JMA EP Flux chart also shows the current u-wind effects well, you can clearly see how weak the vortex is.

 

This is from yesterday and represents the 10hPa level of warming and vortex movement.

Chart courtesy of Weatherbell Analytics.

 

Timing wise the migration from Greenland and lifting out to Siberia commences right at the point where we are on the cusp of will it won't it slider drama, which is also the time of the final MJO decay and also the time of GWO descending into lower orbit. Net result the massive 'entropy' of this week cited by CPC in discussion.

 

d1 > d10 Vorticity and Wave plots - can this wave 1 gather momentum, and will it really need to? Wwith a perturbed messed up vortex that was only a handful of ms-1 away from a technical SSW, another wave gathering strength could peg the vortex back. Caveat being the thing has done a Bear Grylls type job of surviving this winter and is seemingly psychic when it comes to dancing round wave breaks.

 

Another good strat. episode to watch for - will we get a season with a double warming event.. making it a split then a displacement season, time will tell..

 

For GWO and torques Schiraldi's latest GEFS plot, always wary of variance in these, show the cycle through 1 and 2 to end forecast at phase 3 for end Jan > Feb, phase 3 advertising Circumglobal ridges and minimum westerly flow.

 

Here is Jan Phases 3,4 and 5 should we get there.

 

You can see that from a trop. perspective the Jan Phase 5 torque chart has potential to provide wave 2 pinch again and perturb vortex further, also prior to this the solutions for the Scandi Ridging and the Russian High that have been visible in the clusters appear during phases 1 and 2. 

 

Compare this to the 100hPa vortex position and you see again how it seemingly dances around the analogs for blocking developing.

 

Further composites for Feb for reference.

 

So, exciting that whilst we are in a cold snap / spell dependent on which intra-day run you look at that we have yet more interest with the vortex and another will it won't it episode up and coming. We keep watching and learning !

 

 

 

 

[bluearmy]

Are those charts up to date BA?, they aren't updating on my computer, but it could be my computer because de bilt among other things I have struggled with lately.

Jeez, I got caught out.!

Not updated yesterday. Tony posted the heights from yesterday above.

[Duane S.]

Jeez, I got caught out.!

Not updated yesterday. Tony posted the heights from yesterday above.

Updated now. Wave1 incoming...

[bluearmy]

Updated now. Wave1 incoming...

image.jpg

And updated zonal 10 day looks more benign than yesterday. (Though a finger of breeziness evident around the pole right down to the trop).

[Duane S.]

Maybe a mile off but looking at the u winds charts through Jan and I am wondering if the E-QBO worked against us in a perverse way. There was quite a strong poleward surge of Easterlies at around mid strat level earlier this month, getting us far north as around 40N. This left a small area of persistent wind reversals around this area, still present. This has seemingly forced zonal winds downwards at higher latitude than may otherwise have occurred. Did this help scupper a full SSW I wonder?

As it is forecast to finally abate so the finger of zonal wind drops back equatorwards allowing the more benign looking zonal profile where we want it.

[Interitus]

Maybe a mile off but looking at the u winds charts through Jan and I am wondering if the E-QBO worked against us in a perverse way. There was quite a strong poleward surge of Easterlies at around mid strat level earlier this month, getting us far north as around 40N. This left a small area of persistent wind reversals around this area, still present. This has seemingly forced zonal winds downwards at higher latitude than may otherwise have occurred. Did this help scupper a full SSW I wonder?

As it is forecast to finally abate so the finger of zonal wind drops back equatorwards allowing the more benign looking zonal profile where we want it.

 

That is the wind due to the wave 2 pattern, if you look at the current Berlin 10mb chart for example there are two large high geopotential areas causing predominantly easterly mean zonal winds at around 40°N which can be seen in the zonal wind chart.

Look at the last couple of geopotential charts, wave 2 pattern has gone and so has the 40°N easterly.

[sebastiaan1973]

comprendez?

 

Thanks.

[snowking]

Sorry if I'm a bit slow to this, but I notice that Meteociel have now added the GEFS ensemble mean 10mb temperature (Sylvain - PLEASE add heights )

 

Very strong mean signal toward the end of the run for this:

 

 

All pressure on the vortex is good pressure, though lets hope this isn't correlated to the position of any geopotential wave pushing - it would be just our luck to get a Wave 1 displacement from the USA over to the Siberian sector, and then 5 days later get a Wave 1 push from 180 degrees opposite and push the vortex right back over the pole!

 

SK

[bluearmy]

Sorry if I'm a bit slow to this, but I notice that Meteociel have now added the GEFS ensemble mean 10mb temperature (Sylvain - PLEASE add heights )

 

Very strong mean signal toward the end of the run for this:

 

 

 

All pressure on the vortex is good pressure, though lets hope this isn't correlated to the position of any geopotential wave pushing - it would be just our luck to get a Wave 1 displacement from the USA over to the Siberian sector, and then 5 days later get a Wave 1 push from 180 degrees opposite and push the vortex right back over the pole!

 

SK

 

all the evidence points to the vortex ending up in siberia by day 10 with a profile that would have us dribbling if it were to repeat in the trop.

[feb1991blizzard]

Well I am gobsmacked,

 

[feb1991blizzard]

Near to a technical SSW.

 

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2015011800&var=HGT&lev=10mb&hour=384

 

 

Edited January 18, 2015 by feb1991blizzard

[bluearmy]

Near to a technical SSW.

 

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2015011800&var=HGT&lev=10mb&hour=384

 

 

At 10hpa where it is measured, pretty well - yes. And a displacement SSW like this would be good for coldies if it downwells quickly. if it downwells v slowly then Spring could be very delayed this year.

What is encouraging from my perspective is that ECM and gfs ops are both looking the same at day 10.

[feb1991blizzard]

What is encouraging from my perspective is that ECM and gfs ops are both looking the same at day 10.

 

Plus although the GEFS mean isn't quite as aggressive with the warming (you wouldn't expect it to be at that range), it is on the same lines wrt placement of the vortex.

 

 

 

 

Or rather displacement should I say!

Edited January 18, 2015 by feb1991blizzard

[WINTRY WALES]

Was this warming forecast??? Are we looking at a pleasant surprise here? So hopefully the ramifications of this will feed into the trop quickly and the heart of winter will reep the benefits for us in the uk.