Stratosphere Temperature Watch

[chionomaniac]

Temps still predicted to go well above average at the 10mb level and still the relative warmth at the 30mb level is sustained.

Of course, as I should have mentioned yesterday this doesn't necessarily mean a cold pattern for the UK - but nevertheless, a signicantly warm stratosphere for the time of year cannot be a bad thing at all.

Still time of course for the proper annual cool off right back down, but with the east QBO and solar min on our side, then the potential for good things this winter is very much there in respect of the stratopshere and the implications for the polar vortex and opportunities for blocking.

Every time the stratosphere looks like cooling will occur, there seems to be another minor warming. The projected warming at the 10 hPa level I reckon could bring about a Canadian Warming. I wonder is this linked to the fluctuating mountain torques.

http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/gltaum.90day.gif

The CW will need watching all the way down to the troposphere to see if there is any effect.

Typically when I look at how things are shaping up at the 100hPa level at T+120 we see a weak segment of vortex forecast right where we don't want to see it - over the Atlantic - which will keep us in a SW air flow when this is translated into the troposphere below.

You mention T, that we have a significant warm stratosphere for this time of year- here is a chart showing that -

With any further warming that is forecast we are looking at a warm a stratosphere as we have seen - is that the easterly QBO influencing matters? One can see a pulse of negative zonal wind anomalies being propagated down through the layers of the stratosphere. However any NH blocking as a result of this could affect us during the last third of November if it has the legs.

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_UGRD_ANOM_OND_NH_2009.gif

c

Edited November 11, 2009 by chionomaniac

[Fozfoster]

Hi C, Do the warmings always occur in the same areas .

[johnholmes]

as a simple soul the 30mb temps show a marked +ve rise over the past few days, not too dissimilar to early November last year!

say 20-25 days for any effects at the surface, although just where that, if any, effect might be felt?

It will be interesting to watch the AO and NAO, now back on line after a 6 -7 day absence, show over the next 7 days or so; along with how the NOAA 500mb anomaly charts develop their areas of +ve and -ve anomaly and where they try and shunt the Polar Vortex.

Watch my next lrf to see if there any cold signs!

[weatherjunkie]

Zonal winds at all levels of the stratosphere are clearly westerly atm - but they are not unduly strong, and the current prediction at the 30mb level is for them to reduce a little further over the next week.

Also we can see no current organisation of the vortex over the North Pole and towards Greenland

Very interesting topic and I enjoy the discussion.

Would you say that the current warming over the Western Canadian regions favors ridging along the Western U.S and troughing along the Central and Eastern U.S areas over the course of the next 1-1.5 months?

Edited November 11, 2009 by weatherjunkie

[chionomaniac]

Hi C, Do the warmings always occur in the same areas .

The Canadian Warmings - yes. The SSW's tend to follow similar patterns. The vortex disruptions of those can be viewed here.

http://www.appmath.columbia.edu/ssws/index.php

John, I would say that there is already a noticeable difference to the NH stratospheric temperatures when compared to last year with both the 10 and 30 hPa temps up from last year.

08/09

current

That doesn't mean to say that it is going to stay this way but early indications aren't bad.

Very interesting topic and I enjoy the discussion.

Would you say that the current warming over the Western Canadian regions favors ridging along the Western U.S and troughing along the Central and Eastern U.S areas over the course of the next 1-1.5 months?

I would say that depends upon how and if the upper stratospheric profile transmits down to the troposphere. If it does encourage blocking it may not favour it directly below the Canadian stratosphere. Imagine an elephant trunk tornado - landfall does not always occur directly underneath the area of wall cloud from where the tornado is generated. The same may be true of the stratosphere.

[weatherjunkie]

I would say that depends upon how and if the upper stratospheric profile transmits down to the troposphere. If it does encourage blocking it may not favour it directly below the Canadian stratosphere. Imagine an elephant trunk tornado - landfall does not always occur directly underneath the area of wall cloud from where the tornado is generated. The same may be true of the stratosphere.

What sort of things should I be looking for to produce the pattern?

I appreciate the help.

[chionomaniac]

What sort of things should I be looking for to produce the pattern?

I appreciate the help.

I am not quite sure what you mean!! (what pattern?)

Canadian Warmings are normally quite weak affairs and as far as we are concerned they are good at reducing the net vortex strength. I have looked at length for papers implicating signifiacnt tropospheric impacts but have yet to find any.

[weatherjunkie]

I am not quite sure what you mean!! (what pattern?)

Canadian Warmings are normally quite weak affairs and as far as we are concerned they are good at reducing the net vortex strength. I have looked at length for papers implicating signifiacnt tropospheric impacts but have yet to find any.

The pattern I was referring to was the Western US ridging and Central and Eastern US troughing. It was my belief that stratospheric warming occuring in Western Canada would favor such a pattern.

The response you gave to me was:

I would say that depends upon how and if the upper stratospheric profile transmits down to the troposphere. If it does encourage blocking it may not favour it directly below the Canadian stratosphere.

What am I to look for with the troposphere profiles in order to see if there is transmission from the stratosphere to favor the blocking?

[chionomaniac]

The pattern I was referring to was the Western US ridging and Central and Eastern US troughing. It was my belief that stratospheric warming occuring in Western Canada would favor such a pattern.

The response you gave to me was:

What am I to look for with the troposphere profiles in order to see if there is transmission from the stratosphere to favor the blocking?

I would look in three areas. Firstly, the zonal mean wind anomalies to see if any negative anomalies are filtering down to the troposphere.

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_UGRD_ANOM_OND_NH_2009.gif

Secondly, the geopotential height forecasts at all levels of the stratosphere right down to the troposphere to see the shape of the vortex at all levels.

http://strat-www.met.fu-berlin.de/cgi-bin/diagnostics?1

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat_a_f/#emct

From these it may be possible to work out where tropospheric blocking may occur and see if it correlates.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/block.shtml

[weatherjunkie]

I would look in three areas. Firstly, the zonal mean wind anomalies to see if any negative anomalies are filtering down to the troposphere.

http://www.cpc.ncep....OND_NH_2009.gif

Secondly, the geopotential height forecasts at all levels of the stratosphere right down to the troposphere to see the shape of the vortex at all levels.

http://strat-www.met...n/diagnostics?1

http://www.cpc.ncep....strat_a_f/#emct

From these it may be possible to work out where tropospheric blocking may occur and see if it correlates.

http://www.cpc.ncep....MJO/block.shtml

Thank you.

[Guest North Sea Snow Convection]

Thank you.

Hi

Didn't see your post till now, but ch has answered your questions pretty well anyway

Lates update suggests the current above average trend still sustained. It looks like mountain torques judging from the 'snaking' line date and forecast map pattern.

As ch says, there is a chance that this could effect the pattern for us by months end with some 'obliging' downwelling. A progression of the MJO by this time would also be most useful!

[BrickFielder]

As others have said looking at the 10hpa and 30hpa temperatures and pressure tells you more about 3 weeks to a months time than the immediate future. 100hpa temperatures and more importantly potential vorticity at low levels in the straosphere can give some indications of where blocking might occur in the near future.

Blue areas on these chart indicate a bias (quite often shifted by tropospheric influences) towards higher pressure in my opinion.

During novemeber the stratospheric vortex typically starts over russia, so no surprises that is where it is now. What is interesting is that it is forming a little late and not moving north towards the pole as quickly as it does in some years(this shows up as warmer than normal stratospheric temperatures at upper levels). We should remeber that a warming is actually a displacement of the stratospheric vortex away from the pole or a splitting of the vortex). For me this alters the timing (christmas or just after now) of a transition period when the vortex moves north and the UK can expect a brief spell of cold.

Read GP's ideas about the brewer dobson circulation and why late formation and a weak vortex are to be expected and notice also where ozone concentration is highest in the northern hemisphere which explains why the vortex typically starts over russia. Still all to play for especially with a somewhat weak vortex currently.

[weatherjunkie]

I would look in three areas. Firstly, the zonal mean wind anomalies to see if any negative anomalies are filtering down to the troposphere.

http://www.cpc.ncep....OND_NH_2009.gif

Secondly, the geopotential height forecasts at all levels of the stratosphere right down to the troposphere to see the shape of the vortex at all levels.

http://strat-www.met...n/diagnostics?1

http://www.cpc.ncep....strat_a_f/#emct

From these it may be possible to work out where tropospheric blocking may occur and see if it correlates.

http://www.cpc.ncep....MJO/block.shtml

Well, I've taken a look at some of the temperatures and geopotential heights at 10hpa , 30 hpa, and 50hpa and it looks like to me that that there is potential for high pressure to build near or to the west of Greenland and low pressure over the NE Atlantic in the long term.

Taking a look at the 100hpa level, it looks like high pressure will build into eastern Europe, low pressure over the northeast Atlantic and central/eastern Europe.

MJO is in phase 3 and is sort of expected to lollygag in that octant in the week or so. After that a possible jump to phases 7/8 is possible.

Combining those things, would a reasonable forecast for the next 1-2 weeks be a +NAO with a wet western/northern Europe with some reprieve as the MJO is in a favorable phase for dryness? After that in weeks 3-4, a -ve NAO and continued wetness into eastern/northern Europe with some dryness as MJO phases 7/8 by December would favor such a pattern?

MJO Composites

Thank you all for your input. I'm tring to get a feel for all things named "stratosphere".

Hi

Didn't see your post till now, but ch has answered your questions pretty well anyway

Lates update suggests the current above average trend still sustained. It looks like mountain torques judging from the 'snaking' line date and forecast map pattern.

As ch says, there is a chance that this could effect the pattern for us by months end with some 'obliging' downwelling. A progression of the MJO by this time would also be most useful!

As others have said looking at the 10hpa and 30hpa temperatures and pressure tells you more about 3 weeks to a months time than the immediate future. 100hpa temperatures and more importantly potential vorticity at low levels in the straosphere can give some indications of where blocking might occur in the near future.

Blue areas on these chart indicate a bias (quite often shifted by tropospheric influences) towards higher pressure in my opinion.

During novemeber the stratospheric vortex typically starts over russia, so no surprises that is where it is now. What is interesting is that it is forming a little late and not moving north towards the pole as quickly as it does in some years(this shows up as warmer than normal stratospheric temperatures at upper levels). We should remeber that a warming is actually a displacement of the stratospheric vortex away from the pole or a splitting of the vortex). For me this alters the timing (christmas or just after now) of a transition period when the vortex moves north and the UK can expect a brief spell of cold.

Read GP's ideas about the brewer dobson circulation and why late formation and a weak vortex are to be expected and notice also where ozone concentration is highest in the northern hemisphere which explains why the vortex typically starts over russia. Still all to play for especially with a somewhat weak vortex currently.

Thank you for the clarification and information.

[Typhoon John]

I see us being under a trough until the end of the month when there will be a pattern change. But I'm not sure what the change will be yet.

But I see there being frequent opportunities for mountain torques as we head through December and subsequent warming which will help to weaken the polar vortex. I'd expect one of these events will trigger a SSW proper.

[chionomaniac]

Latest update.

Firstly a comparison between the stratosphere at 30hPa from this time last year and now. This year we see a marked reduction in the strength of the vortex and with it further away from the pole.

Last year (vortex strength = 21.8m/s)

This year (vortex strength = 7.4m/s)

And at the 10 hPa level we can see how reduced from normal the polar vortex is:

GP has mentioned the importance of the stratospheric ozone concentration, how the Brewer-Dobson influences this and it's role in increasing stratospheric temperatures which can lead to areas of higher stratospheric pressure. Here is the latest ozone profile which shows an increase in ozone since the beginning of the month.

http://www.cpc.ncep.noaa.gov/products/stratosphere/sbuv2to/gif_files/sbuv17_ll_latest.gif

This is situated across eastern Siberia right across Alaska through to Eastern Canada. Is this influencing the stratospheric temperature and pressure profile?

Here are the GFS temperature profile for 10 hPa for now and forecast for 10 days time:

Now

T+240

A warming is certainly in evidence and this is positioned near the highest concentration of ozone. The respective vortex and forecast vortex at 10 hPa shows a possible build up of pressure over Canada during the corresponding period:

Now

T+240

The ECM suggests something similar:

These forecasts are no way written in stone, but should be monitored to see what occurs. It is difficult to suggest what tropospheric pattern a reduced stratospheric vortex will bring, as there are so many other tropospheric teleconnective influences to take into consideration. Last year I thought that a Canadian Warming may have contributed to a mid latitude high around a month after it occurred and I wouldn't rule out something similar happening this time around as well. But that is the point of this monitoring to see if we can see these correlations.

c

Edited November 14, 2009 by chionomaniac

[Stu_London]

Another excellent analysis - keep them coming

Nice to have met you Thursday also.

[chionomaniac]

Another excellent analysis - keep them coming

Nice to have met you Thursday also.

Cheers Stu,

It was good to meet you and the other guys too.

[Guest North Sea Snow Convection]

These forecasts are no way written in stone, but should be monitored to see what occurs. It is difficult to suggest what tropospheric pattern a reduced stratospheric vortex will bring, as there are so many other tropospheric teleconnective influences to take into consideration. Last year I thought that a Canadian Warming may have contributed to a mid latitude high around a month after it occurred and I wouldn't rule out something similar happening this time around as well. But that is the point of this monitoring to see if we can see these correlations.

c

Taking your theory about the mid latitude high - within the context of the reduced strength vortex this year, then it is not unreasonable to also hypothesise that any rise in pressure that may arise as a result of any warming has the potential to occur at a rather higher latitude than last year. All speculative of course, but entirely possible

[chionomaniac]

Taking your theory about the mid latitude high - within the context of the reduced strength vortex this year, then it is not unreasonable to also hypothesise that any rise in pressure that may arise as a result of any warming has the potential to occur at a rather higher latitude than last year. All speculative of course, but entirely possible

It's certainly not unfeasible is it? The main thing that we are seeing this early into the season is the net mean reduction in polar vortex wind speed. Will this be propagated and influence the tropospheric vortex? It seems a sure thing that it does when the reverse is true!

Currently the stratosphere has negative mean zonal wind anomalies and the troposphere has positive mean zonal wind anomalies.

Is there some kind of Pacific El Nino influence there, as when one looks at the timings, this pattern emerged at the same time as the WWB and El Nino intensification. Will the moderate El Nino be too powerful to allow propagation of negative anomalies from the stratosphere over the Pacific region, opening the door to Atlantic/ Eurasion propagation? All these questions that we do not know the answers to!

[weatherjunkie]

I wonder is this linked to the fluctuating mountain torques.

I believe this should answer your question.

One type of atmospheric wave that exists is called the Rossby wave. Named for Carl G. Rossby, an early atmospheric research scientist, the Rossby wave exists due to a combination of meridional temperature gradients and the rotation of the planet (which produces the Coriolis force). The Rossby wave is a large-scale wave system whose size is thousands of kilometers in the horizontal and several kilometers in the vertical. Large-scale topographical features, like the Rocky Mountains and the Himalaya-Tibet complex, together with the meridional temperature gradients and Coriolis deflection, create a variation of Rossby waves called standing planetary waves. These have very long wavelengths (up to 10,000 kilometers) and either remain stationary or move slowly westward (i.e., they move easterly). They eventually propagate vertically into the stratosphere.

When a standing planetary wave reaches the stratosphere, it deposits its easterly momentum, decelerating the westerly wintertime stratospheric jet stream. This is the polar night jet we discussed in section 2.4.2-c and depicted in Figure 6.02. The polar night jet slows and can even be displaced, which has the effect of displacing the polar vortex region.

The deposition of easterly momentum into the polar stratosphere and the deceleration of the polar night jet is known as "wave breaking" (see section 4.1.2). It produces the phenomenon of the stratospheric sudden warming (see Chapter 2, section 4.2.2) as warmer middle latitude and even tropical air intrudes into the geographic polar region. This result is a situation that is thermodynamically imbalanced. Wintertime radiational cooling in the polar stratosphere quickly begins.

BDC

Basically when the Mountain torque tanked it indicated that Rossby Wave Dispersion was taking place in the mid-latitudes in the N. Hemisphere. The Rossby wave eventually propagated into the stratosphere (may still be propagating into the stratosphere), decelerated the westerly jet stream, and allowed for stratospheric warming to take place.

I believe the reason that both Asia and N. America are seeing the strongest warming is because both areas had Mountain Torques that dropped rapidly below -1 standard deviations multiple times.

Seems reasonable no?

Edited November 15, 2009 by weatherjunkie

[chionomaniac]

I believe this should answer your question.

BDC

Basically when the Mountain torque tanked it indicated that Rossby Wave Dispersion was taking place in the mid-latitudes in the N. Hemisphere. The Rossby wave eventually propagated into the stratosphere (may still be propagating into the stratosphere), decelerated the westerly jet stream, and allowed for stratospheric warming to take place.

I believe the reason that both Asia and N. America are seeing the strongest warming is because both areas had Mountain Torques that dropped rapidly below -1 standard deviations multiple times.

Seems reasonable no?

Yes, it seems very reasonable. My wondering was somewhat rhetorical though - it was more a supposition that the recent MT events were having an influence on the stratosphere. However, it does bring us to another discussion point - that is - in an easterly QBO where the stratospheric vortex is already reduced, will any deflected planetary wave have a greater impact, and have more of an effect than they would ordinarily do so in a westerly QBO with a stronger vortex? I think so, but it is still early in the season and we have yet to see how the vortex will be affected later in the season, when it is stronger.

c

[weatherjunkie]

Yes, it seems very reasonable. My wondering was somewhat rhetorical though - it was more a supposition that the recent MT events were having an influence on the stratosphere. However, it does bring us to another discussion point - that is - in an easterly QBO where the stratospheric vortex is already reduced, will any deflected planetary wave have a greater impact, and have more of an effect than they would ordinarily do so in a westerly QBO with a stronger vortex? I think so, but it is still early in the season and we have yet to see how the vortex will be affected later in the season, when it is stronger.

c

Oh I see

I also believe that there is a greater impact with an easterly QBO.

Only time will tell though.

[Guest North Sea Snow Convection]

Grr, first drop below average indicated at the 10mb level today by ECM forecasts. Is this the traditional seasonal 'cold drop'?

30mb temps still predicted above average - but overall trends need to be watched this week

[cooling climate]

Might this not help with the propagation of the warming down to lower tropospheric levels I wonder.

[karyo]

Grr, first drop below average indicated at the 10mb level today by ECM forecasts. Is this the traditional seasonal 'cold drop'?

30mb temps still predicted above average - but overall trends need to be watched this week

hi Tamara,

it is always a bit worrying this time of year when we see the forecast taking the 10hpa level below average. However, we shouldn't worry too much yet as this is the first day that something like this is shown and might not happen or it may return to above normal pretty soon. Reassuringly, the 30hpa is remaining warm throughout the forecast period!

Ps Cooling climate, I love your picture of the Sarychev explosion! We need a few more of these!

Karyo