Stratosphere Temperature Watch 2012/2013

[chionomaniac]

Yes, Nick, we are seeing the first forecasted assault on the strat, As expected an increase in wave 2 activity is putting some pressure on the stratospheric vortex in FI.

Here at day 10 we see the distorted vortex,

but with no significant warming as of yet.

Remember, yesterday I said that at the geopotential height level we want to see a wave height of greater than 750m to consider it worthwhile and we are approaching that in the forecast:

This is going to have some affect on the mean zonal winds- lowering them as seen below - but I suspect that this will be temporary unless we see some warming as well.

I am not overly optimistic that this will cause too much disruption to the strengthening vortex presently, but this could change if the wave strength grows and a greater warming occurs.

[bluearmy]

Ed, did you notice that the strongest zonal winds seem to pull south away from the area where the wave 2 activity is showing?

[lorenzo]

Looking across the 30hpa line the Zonal wind deceleration is minimal. The negative Easterly QBO wind profile comes under increasing pressure in this run as the extent is cut back from 30N to 20N.

Couple of temperature charts first from the ECM for the Wave 2.

And just a tiny bit of red appeared on the GFS.

At this point you would tend to think Vortex 1 - Waves 0, be interesting to see if the stretched profile elongates enough to split towards end of November.

Edited November 11, 2012 by lorenzo

[chionomaniac]

Ed, did you notice that the strongest zonal winds seem to pull south away from the area where the wave 2 activity is showing?

Yes, but I also note that this is due to the elongation of the vortex - rather than a split - in effect the mean zonal winds are spread over a greater area and yes the jet stream's southern arm will be more enhanced than the northern arm.

The shape of the vortex can be seen clearly looking at the 100 hPa chart -

This is not exactly enticing for us where the main core of the vortex is, though I guess it does offer the possibilities for an easterly further down the line,

or,

if the pressure from the wave 2 increases a possible split - in fact - not too dissimilar to the latest GFS 100 hPa chart at T+240

Hmm, I am starting to get interested now!!

[BLAST FROM THE PAST]

C

What has grabbed me there is the comment re southern arm getting enhanced rather than the northern arm. That is a good starting point and opens up opportunities even if the AO doesn't tank negative a la Jan 1984.

I am interested in this elongated vortex and why the southern arm will get enhanced. The solar cycles IMO have shifted the jetstream south and it is more amplified....I think its affecting the vortex too.

BFTP

Edited November 11, 2012 by BLAST FROM THE PAST

[Glacier Point]

No suprise to see the longer range ECM signalling a rise in pressure to the North and lowering pressure to the south. This is not related to the stratosphere but the lead up to this around mid month (troposperically) will likely have a significant on the stratosphere during the first week December.

A strong build of pressure over Eastern Europe and Western Russia has a teleconnective influence on Wave 2 activity and I'd be very suprised if we didn't see strong wave 2 response in the stratosphere during early December (wave 2 being more responsible for vortex splits). That places us around late December for a stratospheric influenced pattern.

[and wouldn't you know it, we have another tropical wave favouring high latitude blocking mid January - good trop / strat / trop/ strat feedbacks]

.. wave 2 activity showing up around the 13th November. When you consider that the precursor to this (lagged about 20 days), we were looking at twin anomalous ridges over the North Pacific and North Atlantic.

The output for the next 2 weeks is loaded with wave 2 activity further down the line. In particular, anomalous ridges over the Aleutians and E. Europe / Western Russia. Add to that a little potential for wave 1 activity as upper lows spin across the North Pacific sector.

Bottom line, the stuff coming down the tracks at the stratospheric vortex will likely be sustained and favouring splits.

Edited November 11, 2012 by Glacier Point

[bluearmy]

given todays 12z ecm run, i suspect the morning berlin update will be pretty good in the lower strat/trop re zonal wind.

Edited November 11, 2012 by bluearmy

[Relativistic]

Just seen this at day 10 for wave 2:

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=f240&var=ta2&lng=eng

It is day 10 though.

Edited November 11, 2012 by 22nov10blast

[chionomaniac]

That wave is building.

[FrenchScotPilot1]

That wave is building.

How can this graph actually be interpreted? I understand (to a degree) wave temperature, wave heat flux but I'm not too sure about wave geopotential.

Thanks,

Stephane

Edited November 12, 2012 by FrenchScotPilot1

[chionomaniac]

It's no different to the geopotential height of the atmosphere that we measure say at 500 hPa but vertically cut through the stratosphere. The average height at that mean point in the stratosphere is x amount higher for the same pressure.

[FrenchScotPilot1]

It's no different to the geopotential height of the atmosphere that we measure say at 500 hPa but vertically cut through the stratosphere. The average height at that mean point in the stratosphere is x amount higher for the same pressure.

Thanks C.

So to sum up: at 60N around 5hPa, the wave lifts an area 650m higher than normal?

[garbagebags]

Can anyone tell me what causes the polar strat to suddenly and "randomly" warm? Is there something we can be watching that is a trigger for the warming of the strat?

[chionomaniac]

Thanks C.

So to sum up: at 60N around 5hPa, the wave lifts an area 650m higher than normal?

As I understand it - by the stretching of the vortex.

(Remember I am no physicist)

Can anyone tell me what causes the polar strat to suddenly and "randomly" warm? Is there something we can be watching that is a trigger for the warming of the strat?

HI gb , Have you read the first post?

[FrenchScotPilot1]

Can anyone tell me what causes the polar strat to suddenly and "randomly" warm? Is there something we can be watching that is a trigger for the warming of the strat?

Easterly propagating (phase) large Rossby planetary waves lifted by large mountain ranges or land/ocean differential heating propagate into the stratosphere given the right conditions (long wavelength (wave number 1 or 2) and weak westerly flow). They interact with the PV and dissipate create warming.

I gave it a shot I hope I got it right. Please correct me.

Stephane

[garbagebags]

As I understand it - by the stretching of the vortex.

(Remember I am no physicist)

HI gb , Have you read the first post?

Easterly propagating (phase) large Rossby planetary waves lifted by large mountain ranges or land/ocean differential heating propagate into the stratosphere given the right conditions (long wavelength (wave number 1 or 2) and weak westerly flow). They interact with the PV and dissipate create warming.

I gave it a shot I hope I got it right. Please correct me.

Stephane

Ok so nothing a layman like me can understand then lol!

Is there some easy graph I can keep a watch on to see if the strat suddenly warms?

thanks guys

[bluearmy]

Ok so nothing a layman like me can understand then lol!

Is there some easy graph I can keep a watch on to see if the strat suddenly warms?

thanks guys

read page 1 of the thread GB and follow the various links. the berlin link is for ecm and the ncep one for the american NOAA data.

[lorenzo]

CPC has updated, not sure what time exactly as cannot follow the time briefings, ascending / descending orbits and if the information is in US time, unsure how this links to GMT.

The 240 time frame continues to be of interest. 30/50/70/100

30 hpa seems to be the key level the Vortex holding firm.

GPH - again the split is visible at 100 and 50, just there at 70. 30 maintains the core vortex.

interesting to see the H over the area of tropospheric ridging at this time frame.

Also found this slide about time frame leads and the feed backs between Strat and Trop, could do with C or GP helping explain this slide further.

EP flux Vector (Trop) looking livelier too is that a hint of poleward at 60N.

[chionomaniac]

Here is a chart from 30 hPa that I have dug out from last years thread for around the same time of year.

And this year:

It we ignore the minor warming there are two main differences. One is obviously the polar cool core of the vortex - but the other I noticed today which made me look this up to compare. It is the warm mid to tropical temperatures throughout the rest of the stratosphere. This differential can help drive this vortex but also gives us a lot of extra fuel for the fire should a warming occur, and is perhaps indicative of building ozone resources at latitudes further south that the BDC can tap into.

Lorenzo - where is the slide from for further explanation?

Edited November 12, 2012 by chionomaniac

[lorenzo]

Chinese Academy of Science http://www.google.co.uk/url?sa=t&rct=j&q=role%20of%20planetary%20wave%20reflection%20on%20the%20variability%20of%20tropospheric%20weather%20and%20circulation%20pattern%20by%20debashis%20nath%2C&source=web&cd=1&cad=rja&ved=0CB8QFjAA&url=http%3A%2F%2Ficdm2012.csp.escience.cn%2Fdct%2Fattach%2FY2xiOmNsYjpwZGY6MjcwMjA%3D&ei=SvagUMLsKeLF0QXI1oGwBA&usg=AFQjCNGDjIR_ONcgbEk7t-jr9CtWNTsVZQ

http://icdm2012.csp.escience.cn/dct/page/65537

[chionomaniac]

Chinese Academy of Science http://www.google.co...7t-jr9CtWNTsVZQ

http://icdm2012.csp..../dct/page/65537

Cheers I can't download it at work so hopefully will check later. Hopefully it is not in chinese!

[lorenzo]

It's Chinese to me until I can get some understanding from you guys !!

A 2 part paper studies - (a) (b.) below, caught my eye as with the charts just now it appears the coupling described is in presence right now, or at least very shortly. Also the PDO cycle is analysed.

Introduction

In the last few decades, several studies reveal the impact of stratospheric dynamic processes on tropospheric climate

variability through downward coupling between the stratosphere and troposphere. Hines (1974) and Geller and Alpert (1980)

proposed the possibility of planetary wave reflection in the light of stratosphere-troposphere coupling (STC). The subject of

reflection and its impact on the tropospheric field become more and more interesting, with the studies demonstrated the downward

propagation of anomalous zonal mean zonal winds (Christiansen, 2000, Kodera et al., 1990 and Kuroda and Kodera, 1999), STC

processes in relation to the Northern Annular modes (Baldwin and Dunkerton, 1999, 2001) and the downward propagation of

stratospheric signature due to strong wave-mean flow interaction (Baldwin and Dunkerton, 2001; Christiansen, 2001). Recent

statistical works by Perlwitz and Graf (2001) and, Perlwitz and Harnik (2003, 2004) discussed the downward coupling processes of

zonal wavenumber 1 (WN1) and zonal wavenumber 2 (WN2) in the light of stratospheric dynamical states.

They statistically categorized the stratospheric winter states into reflective and non reflective states, using lagged correlation analysis. Kolstad et.al

(2010) demonstrate the development of the lower tropospheric temperature relative to stratospheric weak polar vortex events,

through a series of well defined stages, including the formation of cold air outbreaks. Coughlin and Tung (2005) and Kodera et al.

(2008) observed the reflection of planetary waves in conjunction with major stratospheric warming (SSW) and discussed the impact

on the tropospheric weather regimes.

Motivation of the Present Work

January 2008 experienced record breaking and persistent cold events, snowfalls and freezing rain over West Asia and

central-southern part of China. This extreme event caused extensive damage and general disruption over southern China. Most of

the infrastructure damages were attributed to freezing rain, which led to a huge number of broken power transmission lines and

chaotic traffic conditions for southern China. The disastrous heavy snow caused serious direct economic losses of 53.8 billion RMB

(Zhou et al. 2009).

These motivate us to understand the exact mechanism for the occurrence of such extreme event and also with long

term dataset for decadal variation in the extreme events. Hence in the present work we have highlighted the following two facts as

(a) A case study to understand the January 2008 event.

(b.) A statistical analysis of such cold events in relation with the strength of Polar vortex and phase of PDO.

Edited November 12, 2012 by lorenzo

[Skyraker]

Is it true (amazing to me if it is) that Mountain Torque effects (low pressure one side of a range, high on the other) actually slows the earths spin (albeit miniscule amounts)?

I'm genuinely impressed by that as a backyard astronomer.

Des.

[DAVID SNOW]

FWIW,? The 30-hPa temperature over the north pole as of today,is as low as you would expect in early January.

[Relativistic]

Is it true (amazing to me if it is) that Mountain Torque effects (low pressure one side of a range, high on the other) actually slows the earths spin (albeit miniscule amounts)?

I'm genuinely impressed by that as a backyard astronomer.

Des.

Yes it is. As air pressure builds up on the west side of a mountain range due to a west to east zonal flow, the momentum is transferred to the mountain range which can then speed up Earth's rotation. If the zonal flow is east to west and high pressure builds up on the east of a mountain range it kind of acts like a buffer and the momentum is transferred to the atmosphere, slowing the Earth's rotation down.

That's my understanding of it.

Edited November 12, 2012 by 22nov10blast