Cirus

But, I can tell you that my accent is so frenchy, when I speak English lool ^^. Yes, this thread is international. I know such french people (in another french forum) who come here in order to read such important analysis. But, they don't publish little posts, or replies, in this topic. Yes, absolutely, zonal mean zonal wind will tend to increase sharply, more especially at the top of the stratosphere, due to the weakness of the wave 1 activity. Generally, after a minor displacement event, it is possible to have a single downward propagation of NAM- toward the lower stratoshere, and sometimes toward the troposphere. But those effects doesn’t persist over 2 weeks, as a small wave 1 component maintains the polar vortice (the planetary wave associated propagates only at the edge of the vortex). We can note that a period of vortex intensification appears thereafter, as you say, with a "tidal wave" of NAM+ in the stratosphere, up to the troposphere sometimes. If, the wave 1 component is really too weak, the NAM- values can be really negligible, insignificant in the stratosphere. Recent examples … minor displacement events of 6th January 2011 and 31th January 2011 (approximately). Two years ago, I published a case study on such particular displacement event minor (the abstract is in english, but the rest is in french) and those effects in the troposphere. The link is here If you want to see the whole case study, sorry, it takes to create an account ^^ “Pour revenir à nos moutons†(It’s a french expression^^) In the mid-stratosphere, the polar vortice would be able to be like a bean or in comma shape (very very slightly nevertheless), at the end of this month. After that, indeed, the vortex will enhance with the emergence of wave 0 component, if I can say this. Thanks joggs

Hello everybody ! I'm new to this forum. It's the first time that I write on a foreign forum. I introduce myself briefly. I'm french and I'm 19 years old. I'm student in CPGE (Classes Préparatoires aux Grandes Ecoles). I take care to carry out or to achieve analysis on this website : http://www.espacemeteo.com/Prevision-Meteo/Analyse-stratospherique Excuse me, if my english grammar can be a little bad, or my vocabulary. I've read this topic, sometimes, each winter, since 2011. This thread is very interesting, to follow. I congratulate Chionomaniac, Recretos, and other people for their steady involvement on this topic The extended winter has started since mid-october. We could see a minor displacement event (very minor) in the middle stratosphere. The wave activity, near the stratopause (wave number 1), was born at an early stage for the extended winter. Furthermore, thanks to the wave activity in the troposphere, toward the lower stratosphere (at the end of September and at the beginning of the current month), it allowed to promote this stratospheric event, at 10 hpa. Currently, the extended range forecast abide a vexed question. We must wait the next month, in order to have a better idea on the likelyhood of CW (Canadian Warming), or on the risk of SVI (Stratospheric Vortex Intensification), which can provoke a recurrence of zonal regime above the atlantic ocean and the european continent, through a downwelling of NAM+ in the stratosphere. For the moment, the zonal regime seems to strenghten itself on numerical models. Best regards.