Stratosphere Temperature Watch

[chionomaniac]

Still trying to get to terms with some of this so forgive me if I ask the obvious questions. You mention that firstly, it is worth looking at the GFS's offerings. The GFS is suggesting a vortex split extending from the troposphere into the middle layers of the stratosphere (up to 30 hPa by T+192). Not doubting that for one moment but as the troposphere is very shallow in the arctic winter can I assume that this is from the surface upward?. In other words the vortex (and split) are obvious at all levels. I had a quick look at the 700 and 300mb charts for midnight as an example,

Hi ws, what date are those charts for?

[knocker]

They were for midnight last night ch.

[chionomaniac]

They were for midnight last night ch.

ws, the split in the vortex is not forecast to occur for another 5-6 days so you will have better luck seeing the split then in the 300 hPa and 700 hPa charts. The closer that one gets to slp the more that other factors interact with the vortex split though.

[Glacier Point]

Latest total ozone plot continues to develop medium to high concentrations over the North Pacific which is augering well for sustained tropospheric blocking into December, particularly striking expansion when compared to a week ago.

Direct comparison with last year suggests we are just falling behind the very strong lead from last year, which is not suprising given the underlying west QBO / interference with the Brewer Dobson Circulation, although still positive in terms of future blocking. I'm particularly interested in the location of the highest ozone concentrations.

2009:

2010:

For total ozone, 30mb temperatures are pretty much interchangeable.

Composites for 30mb temperatures positive anomalies in November over the North Pacific / Gulf of Alaska:

Rolled forward into December...

So more of the same for the next few weeks. For the longer term, temperatures over the tropical stratosphere are continuing to rise above normal which is often a precursor to cooling in the polar stratosphere as anomalous upwelling takes place (adiabatic cooling) and this needs to be watched only a daily basis.

[chionomaniac]

Ha, I think that I have misread a negative mountain torque for a positive one over the Himalayas. Easy to do I suppose!

[bluearmy]

Ha, I think that I have misread a negative mountain torque for a positive one over the Himalayas. Easy to do I suppose!

which is bad news chiono as you were rather hoping that would lead to another wave headed into the polar region to disrupt a reforming p/v. Stewart seemed to agree with you - strange that both of you would have misread it. given the dropping strat temps forecast by berlin, will be intersting to watch the fi nwp 'putting humpty together again'. he is currently blown apart by day 10 !!

[chionomaniac]

which is bad news chiono as you were rather hoping that would lead to another wave headed into the polar region to disrupt a reforming p/v. Stewart seemed to agree with you - strange that both of you would have misread it. given the dropping strat temps forecast by berlin, will be intersting to watch the fi nwp 'putting humpty together again'. he is currently blown apart by day 10 !!

Oh I don't think that it is bad news, ba. What would be bad news would be no significant torque event at all. Let's see what happens.

Already we see a resurgence of wave 2 activity forecast in the stratsophere.

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=all&var=uv2&lng=eng

Will this possibly lead to further warming before the stratosphere cools dramatically?

GFS shows today that the vortex split extends to the 10 hPa level

What is strange is that as of yet, the mean temperatures and zonal winds show no signs of dropping between 60-90ºN.

[Glacier Point]

which is bad news chiono as you were rather hoping that would lead to another wave headed into the polar region to disrupt a reforming p/v. Stewart seemed to agree with you - strange that both of you would have misread it. given the dropping strat temps forecast by berlin, will be intersting to watch the fi nwp 'putting humpty together again'. he is currently blown apart by day 10 !!

Nope - I was looking at the +ve torque now occuring over the Himalayas, probably the weaker of the two to occur in the next 20-30 days.

[chionomaniac]

Nope - I was looking at the +ve torque now occuring over the Himalayas, probably the weaker of the two to occur in the next 20-30 days.

I was trying to guess the torque by looking at the East Asian models. What I though would lead to a negative torque is leading to a positive one - I won't make that mistake again!

[Guest harshwinter09]

What is strange is that as of yet, the mean temperatures and zonal winds show no signs of dropping between 60-90ºN.

Is that good or bad in terms of blocking and its longevity?

[chionomaniac]

Is that good or bad in terms of blocking and its longevity?

As I said it's strange.

Normally vortex disruption events follow a pattern. Warm air enters the vortex leading to an increase in net temperatures and decrease in mean zonal winds. This current forecast disruption does seem to be tropospherically led and could be as a consequence to an earlier slight stratospheric warming.

[johnholmes]

This current forecast disruption does seem to be tropospherically led and could be as a consequence to an earlier slight stratospheric warming.

I put into my own lrf ideas on my pc(not posted) much the same thoughts, although in another possible post I've talked about still being far from certain about any of these warming events small or large.

They sometimes seem to work but I suspect, as in January 2009, other things which we may not be aware of need to be 'right' for the cold spell to occur?

[Guest harshwinter09]

As I said it's strange.

Normally vortex disruption events follow a pattern. Warm air enters the vortex leading to an increase in net temperatures and decrease in mean zonal winds. This current forecast disruption does seem to be tropospherically led and could be as a consequence to an earlier slight stratospheric warming.

So the warm air has propogated down to the troposphere?

Does the fact that the event is tropospherically led mean that the warm air which is there at present is likely to dissipate quicker than if the disruption were to be stratospherically led?

thanks.

[chionomaniac]

I put into my own lrf ideas on my pc(not posted) much the same thoughts, although in another possible post I've talked about still being far from certain about any of these warming events small or large.

They sometimes seem to work but I suspect, as in January 2009, other things which we may not be aware of need to be 'right' for the cold spell to occur?

I think GP is on the right lines John, when he mentions the upward or downward propagating waves throughout the stratosphere. This has been reported in some papers as well. Perhaps if tropospheric led disturbances coincide with upward propagating waves then bingo. Likewise for MMW's and downward waves.

[Fozfoster]

As I said it's strange.

Normally vortex disruption events follow a pattern. Warm air enters the vortex leading to an increase in net temperatures and decrease in mean zonal winds. This current forecast disruption does seem to be tropospherically led and could be as a consequence to an earlier slight stratospheric warming.

do you mean mid october, i thought warming did not start this early! or is it warming and cooling all year round. God i like reading this thead but i must be thick:cc_confused:

Edited November 16, 2010 by fozfoster

[chionomaniac]

So the warm air has propogated down to the troposphere?

Does the fact that the event is tropospherically led mean that the warm air which is there at present is likely to dissipate quicker than if the disruption were to be stratospherically led?

thanks.

There is no evidence that warmer air has propagated down to the troposphere. What is more likely is that warmer air in upper levels of the stratosphere cause a disturbance in the vortex shape that can assist in tropospheric led disturbances.

do you mean mid october, i thought warming did not start this early! or is it warming and cooling all year round. God i like reading this thead but i must be thick:cc_confused:

Here is the temp graph for an average year which gives you an idea of how the polar stratosphere cools and warms throughout the year.

http://acdb-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/t60_90n_30_2010.pdf

[Guest harshwinter09]

There is no evidence that warmer air has propagated down to the troposphere. What is more likely is that warmer air in upper levels of the stratosphere cause a disturbance in the vortex shape that can assist in tropospheric led disturbances.

And it is that warmer air at present in the stratosphere which is about to cause the upcoming cold spell?

The warm air has had an effect on the troposphere as I think you stated in your last update on what the charts are showing?

[chionomaniac]

And it is that warmer air at present in the stratosphere which is about to cause the upcoming cold spell?

The warm air has had an effect on the troposphere as I think you stated in your last update on what the charts are showing?

It is the disturbed split vortex that will be responsible for the upcoming blocking which could possibly lead to a cold spell. I think that how much recent stratospheric warming has contributed is difficult to assess.

[johnholmes]

I think GP is on the right lines John, when he mentions the upward or downward propagating waves throughout the stratosphere. This has been reported in some papers as well. Perhaps if tropospheric led disturbances coincide with upward propagating waves then bingo. Likewise for MMW's and downward waves.

thanks ch, other than GP's links have you any that show this please?

[chionomaniac]

thanks ch, other than GP's links have you any that show this please?

Sorry, John. That could take some time as I browse a fair few papers and don't bookmark them all.

One other chart that I forgot to post earlier is the 100 hPa chart for T+240. This is different to the previous and suggests that the Scandi trough has a good chance of dropping and that the Greenland high won't as was suggested in yesterdays output.

[knocker]

In an earlier post GP talked of "For the longer term, temperatures over the tropical stratosphere are continuing to rise above normal which is often a precursor to cooling in the polar stratosphere as anomalous upwelling takes place (adiabatic cooling) and this needs to be watched only a daily basis."

I'm not sure I understand the mechanism that causes anomalous upwelling leading to adiabatic cooling. I take it we cannot be talking wave propogation here.

Edited November 17, 2010 by weather ship

[Mikel Nimbus]

There's something weird going on on the 06Z GFS run. Looking at the 850 temps I'm wondering if this could be evidence of downwards propogation of warmer air into the Troposphere? Out of nowhere a warm pool of air develops off the east coast of Greenland from +90. It then looks like it gets caught by the jet and dragged SEwards.

On the other hand, I haven't had a chance to check the ensembles so it could just be GFS throwing a wobbler.

Edited November 18, 2010 by Mikel Nimbus

[Nick B]

There's something weird going on on the 06Z GFS run. Looking at the 850 temps I'm wondering if this could be evidence of downwards propogation of warmer air into the Troposphere? Out of nowhere a warm pool of air develops off the east coast of Greenland from +90. It then looks like it gets caught by the jet and dragged SEwards.

Surely to check for this you'd need to look at the level higher in the atmosphere, i.e. 500 hPa, before you'd see anything mixed down as relatively low as the 850's?

I can't see the propagation making that far down myself. I would have thought its significant effects would be above the 500hPa level?

[Mikel Nimbus]

Surely to check for this you'd need to look at the level higher in the atmosphere, i.e. 500 hPa, before you'd see anything mixed down as relatively low as the 850's?

I can't see the propagation making that far down myself. I would have thought its significant effects would be above the 500hPa level?

Fair point. On closer inspection of 500s it seems it's connected to that wave of warm air extending up from the Atlantic. :blush: :blush: :blush:

Edited November 18, 2010 by Mikel Nimbus

[Kentish Kiwi]

Fair point. On closer inspection of 500s it seems it's connected to that wave of warm air extending up from the Atlantic. :blush: :blush: :blush:

Possibly the warmer air being cooled more at the surface level and 850 due to the entrenched cold over the land of Greenland itself but is allowed to have more of a warming effect over the relatively mild sea to the east? Hence the warm pool popping up on the east coast as it 'leap-frogs' the land from the west...