Stratosphere Temperature Watch

[johnholmes]

I certainly would prefer this thread to be kept to the monitoring of the tropospheric/stratospheric interaction from this winter only. The interesting link of climatic stratospheric changes to solar wind and other non tropospheric influences certainly needs investigating but that is probably best left to its own thread, I agree.

c

I would agree with this request, keep them in separate threads, both need investigating but separately.

[chionomaniac]

Looking today at the mean zonal wind forecast we can see that it is completely different from yesterdays. In fact it couldn't be more different for the 4th March, the date we showed yesterday.

This doesn't surprise me as the propagation of the negative wind anomalies has been something that has been poorly forecast from around three days out . The polar troposphere negative wind anomalies pointed out in yesterdays ECM stratosphere forecast were not forecast by the ECM's own model output. These would have shown as noticeable polar high pressure blocking which there was no sign of. I think I will only take notice in future when the ECM stratosphere and troposhere model forecasts marry up. Today the two do so, suggesting the forecast is likely to be more accurate than yesterdays.

c

[Gray-Wolf]

Never mind the knowledge I am gaining from you guys it is also 'sweet' to see you guys learning along with us!

[chionomaniac]

There seems to be good agreement between the GFS and the ECM lower stratospheric forecasts for five/six days out.

This fits in with the tropospheric model outputs with a trough covering the UK with a predominantly NW air flow.

The trend further out to 10 days is for this to continue which if it verifies will keep the UK in cooler spring weather.

The area most likely to see height rises to our north from these charts is possibly around Scandinavia with the trough being cut off and undercutting.

Further above the negative wind mean zonal anomalies are finally eroding above the North Pole. Whether the westerlies that are replacing them will push negative mean winds into the troposphere remains to be seen.

c

[BLAST FROM THE PAST]

Gray Wolf

In my view you are on pretty firm ground. The geomagnetic indices that reflect the solar wind also reflect the incidence of energetic particle precipitation events that produce nitrogen compounds in the mesosphere that are carried down into the polar stratosphere where they erode ozone.

The ozone content of the stratosphere and upper troposphere drives temperature in the ozone rich areas and the mid latitude high pressure cells are ozone rich. For this reason 200hPa temperature in these regions varies independently of surface temperature. This directly affects vorticity and surface wind strength together with ice cloud cover and has knock on effects in terms of the strength of the Hadley circulation and the location of the jet streams.

There is evidence in the recent cooling of the equatorial stratosphere conjunctional with warming of the Arctic stratosphere that the solar wind is capable of shifting the atmosphere and thereby changing the density of the optical path that the suns rays must traverse to reach the surface. I can not think of any other way that the equatorial stratosphere is forced to cool as the mid latitude and polar stratosphere warms. What do you think?

Hi Erl

You are describing nicely the effects of a HALE Cycle winter and what synoptically seems to have happened this winter too.

BFTP

[mountain shadow]

Without meaning to belittle this thread or sound rude but would it now be correct to say that an MMW (or whatever it may be called) in isolation, does not increase the likliehood of a major cold event for the British Isles?

[chionomaniac]

Without meaning to belittle this thread or sound rude but would it now be correct to say that an MMW (or whatever it may be called) in isolation, does not increase the likliehood of a major cold event for the British Isles?

No, not at all, it would just show that you haven't actually read the thread.

[carpo21]

One of the best new threads to emerge on NetWeather. Absolutely fascinating to read in conjuction to predicted and actual weather, and more importantly, how it can be used to further our understanding and realisation of more accurate long term forecasting - is there anything else like this on the web? Great stuff, keep it up everyone!

[chionomaniac]

One of the best new threads to emerge on NetWeather. Absolutely fascinating to read in conjuction to predicted and actual weather, and more importantly, how it can be used to further our understanding and realisation of more accurate long term forecasting - is there anything else like this on the web? Great stuff, keep it up everyone!

Thanks carpo.

I reckon that there is still a long way to go in the research of how the stratosphere may influence tropospheric weather. I think it will be an area where increased importance will be shown with regard to longer range forecasting and pattern correlation. But there is still so much to learn.

c

[Erl Happ]

Hi Erl

You are describing nicely the effects of a HALE Cycle winter and what synoptically seems to have happened this winter too.

BFTP

Reply at http://www.netweather.tv/forum/index.php?s...p;#entry1472929

[Guest North Sea Snow Convection]

No, not at all, it would just show that you haven't actually read the thread.

Indeed, quite a few pages now I believe?

There is no doubt that the atmosphere will respond in kind to any shuffle in the pack between its upper and lower stratas. What we have been trying to do is disseminate the likely direction, timing and placement of any such responses and potential repercussions. There are always reactions to waves - which make waves - but are we placed on the right side of the global pond to receive any vibrations??

[chionomaniac]

Today when comparing the mean zonal wind anomaly charts (which show easterly winds at the NP) to the ECM NH 500 charts I have trouble in seeing how they are both singing from the same hymn sheet ( for 3rd March). The NH 500 shows a fairly strong upper vortex with possibly a very weak surface high around the NP. Surely this isn't enough of a pressure rise and the mean zonal wind anomaly chart would indicate something a lot stronger?

Without these two charts indicating the same thing it puts doubt in my mind, mainly with the stratospheric forecast.

We have postulated a lot on here as to why propagation hasn't occurred of the MMW of the zonal mean winds that would enhance the chances of northern blocking. Looking back though I believe that propagation has occurred right from the start of the MMW.

Looking at the above chart it is obvious that considerable downwelling of the negative mean zonal winds has occurred and it cannot be ignored. So why no northern blocking? Well, I believe now that the troposphere is not only instrumental in the original trigger for the MMW, but it is fair to say that the tropospheric state is also crucial in how any propagation of the negative mean zonal winds filter through the tropopause. What I feel we needed to see existing in the troposphere is a highly amplified pattern rather than a flatter one that we have just experienced. The propagation of the negative zonal winds has been drip fed into the troposphere from the stratosphere and this has just served to weaken further an already flat jet pattern rather than enhance the northern blocking from an amplified one. When you add to this that there was only one burst of stronger negative winds at the start of the month and perhaps no stronger forcing from above we may now explain why our high hopes may have been dashed.

When we said that a MMW will increase the chances of cold but that it does not guarantee this we have classically seen why. We have seen an unprecedented MMW that has given us one cold spell but has also left a daughter cell over western Greenland cutting off the cold air source followed by slow propagation (almost dissipation) on a flat jet which has stopped us gaining as much as we would have liked.

c

Edited February 28, 2009 by chionomaniac

[Guest North Sea Snow Convection]

I think the thing is though that complete propagation of the anomalies should still dissipate the surface low pressure 'inversion' (as it has been referred to previously). Therefore, although it is true as you say that an amplified pattern would assist the break up of this inversion - irrespective of the pattern of the jet, pressure should still be able to rise over the polar field with ridging occuring out of the arctic. Last nights ECM, if one looked at the NH chart and ran the output through to day 10 was a classic illustration of the process happening as if that final propagation was happening. Negative zonal anomalies, by dint of what they are, reverse the normal jet polarity, so westerly energy at the surface should be unsupported - assuming full propagation. Therefore it is my view that although there has indeed been downwelling from the start of the MMW, the final propagation hasn't (can't) have yet fully occured and the surface low pressure has therefore remained - ie as manifested for eg by the daughter cell near Greenland.

You may well of course be right - it will be very interesting to see what does eventually happen - but at least for the timebeing I still remain of the view that this process will eventually happen, and it will arrive at short notice. It is not just coincidence or just down to wild FI model output that both the ECM and GEM models have clearly hinted at this process in the last few days.

[johnholmes]

has anyone got access to the upper air charts through mid January with, if I remember correctly, a cold fairly zonal flow? Little in the way of flow amplification but then the rapid transition over, what (?), 48 hours or so to the deep cold of 1 February?

I am still not convinced that was Stratosphere induced or at least not in the way we/me seem to have accepted what happens in terms of time lag?

Edited February 28, 2009 by johnholmes

[chionomaniac]

I think the thing is though that complete propagation of the anomalies should still dissipate the surface low pressure 'inversion' (as it has been referred to previously). Therefore, although it is true as you say that an amplified pattern would assist the break up of this inversion - irrespective of the pattern of the jet, pressure should still be able to rise over the polar field with ridging occuring out of the arctic. Last nights ECM, if one looked at the NH chart and ran the output through to day 10 was a classic illustration of the process happening as if that final propagation was happening. Negative zonal anomalies, by dint of what they are, reverse the normal jet polarity, so westerly energy at the surface should be unsupported - assuming full propagation. Therefore it is my view that although there has indeed been downwelling from the start of the MMW, the final propagation hasn't (can't) have yet fully occured and the surface low pressure has therefore remained - ie as manifested for eg by the daughter cell near Greenland.

You may well of course be right - it will be very interesting to see what does eventually happen - but at least for the timebeing I still remain of the view that this process will eventually happen, and it will arrive at short notice. It is not just coincidence or just down to wild FI model output that both the ECM and GEM models have clearly hinted at this process in the last few days.

I don't think the final propagation has occurred either. These were just my thoughts about the intervening period between easterly and final propagation.

has anyone got access to the upper air charts through mid January with, if I remember correctly, a cold fairly zonal flow? Little in the way of flow amplification but then the rapid transition over, what (?), 48 hours or so to the deep cold of 1 February?

I am still not convinced that was Stratosphere induced or at least not in the way we/me seem to have accepted what happens in terms of time lag?

It was induced John because of the split in the vortex , not because of classic downwelling of the negative mean zonal winds. The vortex split quite clearly threw out a vorticity segment westwards into the Atlantic from the Siberian daughter. Look at the end of the following animation.

http://earthobservatory.nasa.gov/images/im...o_200901-02.mov

c

Edited February 28, 2009 by chionomaniac

[johnholmes]

tks ch, have you got any upper air charts to show before and after so to speak?

[chionomaniac]

tks ch, have you got any upper air charts to show before and after so to speak?

Here's one from 100 hPa for around that time

[johnholmes]

thanks

sorry to be a pain, can you post the link for anything one can look at retrospectively, say 5 days either side of the one you have shown, also for lower in the atmosphere for the same dates please?

don't ask for much do I?

[chionomaniac]

thanks

sorry to be a pain, can you post the link for anything one can look at retrospectively, say 5 days either side of the one you have shown, also for lower in the atmosphere for the same dates please?

don't ask for much do I?

I don't think I have them saved so sorry probably not though the animation above I think is as good as you can get.

[tundra]

The jet stream prior to the mmw was in a highly amplified state over north America with a very strong + pna signal. It was from the ridge from hell as the Americans like to call it (west coast ridge) that the warming in the stratosphere took place (on the Alaskan side and over Greenland).

I remember thinking it is only a question of time before a colder pattern affects us due to the amplified pattern upstream regardless of any warming in the stratosphere.

With the stratosphere in such a relaxed and subdued state we could very well of locked into a very cold pattern for several weeks had it not been for a weaker piece of the daughter vortex that cruely took up residence over Greenland pushing the northern blocking and very cold and wintry weather into Europe.

Unfortunately because of the strength of the warming there was no strong downwelling to move the vortex away from Greenland hence the way the rest of February panned out. Also because there was no more strong sub tropical forcing mixing with the polar westerlies to produce some inertia into the stratosphere if i can put it that way then everything stayed in a state of status quo.

Perhaps this is how negative cet months in the past have occurred in which case we were very very unlucky.

Edited February 28, 2009 by tundra

[johnholmes]

thanks for that Tundra

all sounds probable to me - almost, not quite (!) sorry I missed that with my skiing holiday!

[Guest North Sea Snow Convection]

I'm now starting to wonder if rather than the MMW leading into an FW we are going to actually see in contrast a very late FW instead. Temps at 10mb level continue to indicate a fall away and forecasts are now to a significantly below average level. As 10mb and 30mb zonal winds now go back to westerly this could mean that it is quite some time before the easterlies return.

Looking back we can see the winter cooling period of the stratosphere came later this winter during late Dec and the first half of Jan leading up to the MMW in what has a been an obstinate west QBO state. Perhaps with only slow demise of the west QBO we are now going to see a late disintegration of the winter time vortex in compensation for the later start, with the MMW splitting only a very sharp interruption in the middle of it?

Maybe it it will be the case that we will see a blocked period during March to reflect the final downwelling of the negative zonal anomalies left over from the MMW but then as tropospheric zonal winds increase once more in response to the cooling now underway in the stratosphere we might see this blocking sink south to mid latitudes further on during April and into May?

This all leaves one wondering when the FW will eventually occur? And when the easterly QBO phase starts, as that might be the key.

More questions than answers remain.

Edited March 3, 2009 by North Sea Snow Convection

[chionomaniac]

I'm now starting to wonder if rather than the MMW leading into an FW we are going to actually see in contrast a very late FW instead. Temps at 10mb level continue to indicate a fall away and forecasts are now to a significantly below average level. As 10mb and 30mb zonal winds now go back to westerly this could mean that it is quite some time before the easterlies return.

Looking back we can see the winter cooling period of the stratosphere came later this winter during late Dec and the first half of Jan leading up to the MMW in what has a been an obstinate west QBO state. Perhaps with only slow demise of the west QBO we are now going to see a late disintegration of the winter time vortex in compensation for the later start, with the MMW splitting only a very sharp interruption in the middle of it?

Maybe it it will be the case that we will see a blocked period during March to reflect the final downwelling of the negative zonal anomalies left over from the MMW but then as tropospheric zonal winds increase once more in response to the cooling now underway in the stratosphere we might see this blocking sink south to mid latitudes further on during April and into May?

This all leaves one wondering when the FW will eventually occur? And when the easterly QBO phase starts, as that might be the key.

More questions than answers remain.

Hi Tamara,

I agree with you here about it now looking more than likely that we are going to have a delayed Final Warming.

ftp://hyperion.gsfc.nasa.gov/pub/ftpmet/n...60n_10_2008.gif

Looking at the zonal mean winds they are indeed climbing when the usual trend at this time of year is the exact opposite. However they are not yet above the average for this time of year.

With the stratospheric vortex regaining strength, will that lead to a more Atlantic based Spring once the final effects of the MMW have worn off?

Earlier in this thread we wondered whether the westerly QBO would prevent a MMW from ocurring, as the timeframe clashed with the solar minimum, and that it had never occurred before when the two coincided. We now know that that wasn't to be the case but after further reading of the GWO thread it does make perfect sense that even though the westerly QBO didn't prevent the MMW from occurring, it may have instrumental in preventing the anticipated propagation. This has only served in reducing angular momentum, with corresponding weakening of the jetstream (also keeping it south) and combined with the weak La Nina state, no amplication in the flow, ultimately we have seen the net result being no northern blocking.

For those who have wondered (including myself) why this MMW has not delivered as anticipated it is good finally to have a credible reason why this is so. It also shows us how all tropospheric factors need to be pointing in the right direction as well, to obtain maximum benefit form a MMW.

I for one feel that I have learned loads from this last winter!

c

[Glacier Point]

http://www.cdc.noaa.gov/map/images/reanaly...ltaum.90day.gif

something of a watching brief required I think w/r/t wave-breaking.

[tundra]

Hi Tamara,

I agree with you here about it now looking more than likely that we are going to have a delayed Final Warming.

ftp://hyperion.gsfc.nasa.gov/pub/ftpmet/n...60n_10_2008.gif

Looking at the zonal mean winds they are indeed climbing when the usual trend at this time of year is the exact opposite. However they are not yet above the average for this time of year.

With the stratospheric vortex regaining strength, will that lead to a more Atlantic based Spring once the final effects of the MMW have worn off?

Earlier in this thread we wondered whether the westerly QBO would prevent a MMW from ocurring, as the timeframe clashed with the solar minimum, and that it had never occurred before when the two coincided. We now know that that wasn't to be the case but after further reading of the GWO thread it does make perfect sense that even though the westerly QBO didn't prevent the MMW from occurring, it may have instrumental in preventing the anticipated propagation. This has only served in reducing angular momentum, with corresponding weakening of the jetstream (also keeping it south) and combined with the weak La Nina state, no amplication in the flow, ultimately we have seen the net result being no northern blocking.

For those who have wondered (including myself) why this MMW has not delivered as anticipated it is good finally to have a credible reason why this is so. It also shows us how all tropospheric factors need to be pointing in the right direction as well, to obtain maximum benefit form a MMW.

I for one feel that I have learned loads from this last winter!

c

There was northern blocking but it got pushed east over Scandinavia and western Russia by a segment of the daughter vortex moving into Greenland. If it wasn't for this small piece of vortex energy i am positive we would have had a very prolonged very cold spell in February.

Admittedly we did not see anything like the amount of blocking we thought we would see and this i think was down to very slow propagation of the warming after the initial burst, due in part to the strength of the warming and the very relaxed state the stratosphere was left in.

Had we been in a easterly QBO instead of west would things have been different i do not know.