Stewart heeft gisteren een update gegeven.
We are away from the solar minima and in a second cold season east QBO. That will lead to a cooling stratospheric profile. But here's the deal, with this type of QBO, especially going into a second cold season and solar activity relatively low, this is tantamount to a ticking time bomb. There is a high probability this winter of one or more warming events. Our nearest comparison year, 1968, had its first warming in late November.
For reference, I've collected 21 October ozone data from 2012, 2011 and 2009 to give us a fix on where we stand currently:
http://forum.netweather.tv/topic/74587- ... try2387855 -> daar te vinden
Not bad, not as expansive as 2009 but certainly better than 2011. The relaxation of the warming in the southern hemisphere should assist the BDC make its contribution more felt in the NH in the coming weeks.
Also, note the rapid increase in Eurasian snowcover that has happend and will continue to consolidate with the projected pattern for the next 10 days. That gives every chance that zonal wind flow will be disriupted and eddy fluxes will begin to develop over Siberia and into the North Pacific. Already I'm seeing first indication of falling heights across the North Pacific which begins to initiate the longwave response across the NH - look out for increasing wave 1 activity in the coming weeks which will persist strong +ve heights to the north and NE. We should expect to see low pressure in the Atlantic but more with the jet orientated NW-SE or even more meridional. Ideally we want this North Pacific low and a ridge over eastern Europe to set in train a warming event.
he profile of this QBO since its development last year mirrors a few in the last 50 years. There is a discernible difference in east QBOs away from solar minima in how they perpetuate across the equator and 10N, depending on thier longevity. For QBOs lasting this long, there is a trend towards light to moderate zonal wind increase in the autumn across 70N, followed by interuptions to this during November, December and January - 1968 being a classic example.
For snowcover, see above papers. The basic gist being:
- sudden expanse in snowcover develops a pool of cold air which acts like a brick wall to the zonal flow;
- tropospheric response is for frictional torques to develop 40N;
- poleward eddy flux follows as a response;
- anticyclones develop on poleward flank of the eddy, initiating Rossby Wave train and alteration of entire NH longwave pattern - Aleutian low the notable one;
- in turn the tropospheric longwave pattern re-inforces itself with wave breaking into the stratosphere and decceleration of the polar night jet.