Using stratospheric wave amplitude anomalies to forecast

[wxmx]

These past few winters (including these) have seen some record setting high latitude blocks and/or SSWs. There are tools that may help forecasting this events. One of these is stratospheric Waves. I'm going to insert some images to better explain how Wave 1/2 amplitude anomalies might help make some higher confidence calls.

Record breaking SSW of late January 2009, during an apparently unfavorable period (Solar min, +QBO, La Niña/neutral cold)

Record breaking -AO during Dec past winter...with a second peak early Jan 2010

SSW late Jan 2010

Strong -NAO late November with a stronger record peak now and ongoing -AO

[Srain]

Great information as usual, Jorge.

[meteorologist]

http://www.weatheranswer.com/public/Strat.pdf

[Yes_Probably_Maybe_No]

I gather from this that "wave breaking" happens in an almost literal sense. The amplitude of the wave breaks into pieces ergo a SSW event. Does this sound like a good basic summarization?

Dec 17th Euro

Day 1

Day 10

Could this concept be applied to geopotential maps as well?

[wxmx]

I gather from this that "wave breaking" happens in an almost literal sense. The amplitude of the wave breaks into pieces ergo a SSW event. Does this sound like a good basic summarization?

Dec 17th Euro

Day 1

Day 10

Could this concept be applied to geopotential maps as well?

I'm not an expert on these matters, but from my limited knowledge these waves are produced in the troposphere and transported to the stratosphere trough several mechanisms, most notably by the nature of our rugged Earth, which deflect the natural West-East motion of the lower atmosphere. As it's forced upward (because of terrain, for example) and downward, due to gravity, they form waves in the troposphere (Rossby waves), which gives birth to our well known troughs and ridges. Sometimes this waves are so extreme in it's ascending part that they reach the stratosphere with full strength. This phenomena alters the relative stability of the stratosphere, and may induce wind direction changes that may break the shield to the polar vortex...better known as the polar-night jet stream.

Now, how does all this affect the high latitudes in the troposphere? A disrupted polar vortex has "leaks of cold" and this usually propagates back to the troposphere. A weak PV is warmer and "looser", as opposed to circlish and tight, and this helps the lower atmosphere get a more meanderish look, big ridges poke the artic circle while major troughs enter the mid-latitudes, spreading the cold. Also, a cold stratosphere kills ozone, so a continous assault of these warm waves prevents ozone depletion. The role of ozone is a major one wrt stratospheric warming, as the ozone itself generates warming, so there's one positive feedback.

Talking about ozone, we also have the top-down (stratosphere->troposphere) process...as opposed to the down-top-down one...Ozone in the stratosphere is produced with the help of the sun, UV rays do the trick. But also the solar wind, which is composed by subatomic particles may create havoc, as they ionize other elements (like nitrogen and hydrogen), which are oxygen hungry, and being an unstable molecule, the ozone easily breaks up in the presence of such ionized elements, helping depletion. Currently we are in a very dampened solar cycle, which keeps solar wind down, so ozone might run at higher concentrations in the polar stratosphere, hence the warming. There might be other mechanisms, but like I said before, I'm far from being an expert. But let's say that the stratosphere is "receptive".

So, we are probably in a very favorable state for high latitude blocking, and high amplitude waves disrupting and warming the PV had and probably will keep ridging forming in the high latitudes. I'm not expecting severe/continuous -AO/-NAO, it has to give sometimes, but overall a disturbed state will be favored as long as we keep those favorable feedbacks going.

BTW, looks like another high amplitude wave is making it's way. Let's see how strong it gets.

[wxmx]

Some good reading

Upward Wave Activity Flux as a Precursor to Extreme Stratospheric Events and Subsequent Anomalous Surface Weather Regimes

[Yes_Probably_Maybe_No]

I'm not an expert on these matters, but from my limited knowledge these waves are produced in the troposphere and transported to the stratosphere trough several mechanisms, most notably by the nature of our rugged Earth, which deflect the natural West-East motion of the lower atmosphere. As it's forced upward (because of terrain, for example) and downward, due to gravity, they form waves in the troposphere (Rossby waves), which gives birth to our well known troughs and ridges. Sometimes this waves are so extreme in it's ascending part that they reach the stratosphere with full strength. This phenomena alters the relative stability of the stratosphere, and may induce wind direction changes that may break the shield to the polar vortex...better known as the polar-night jet stream.

Now, how does all this affect the high latitudes in the troposphere? A disrupted polar vortex has "leaks of cold" and this usually propagates back to the troposphere. A weak PV is warmer and "looser", as opposed to circlish and tight, and this helps the lower atmosphere get a more meanderish look, big ridges poke the artic circle while major troughs enter the mid-latitudes, spreading the cold. Also, a cold stratosphere kills ozone, so a continous assault of these warm waves prevents ozone depletion. The role of ozone is a major one wrt stratospheric warming, as the ozone itself generates warming, so there's one positive feedback.

Talking about ozone, we also have the top-down (stratosphere->troposphere) process...as opposed to the down-top-down one...Ozone in the stratosphere is produced with the help of the sun, UV rays do the trick. But also the solar wind, which is composed by subatomic particles may create havoc, as they ionize other elements (like nitrogen and hydrogen), which are oxygen hungry, and being an unstable molecule, the ozone easily breaks up in the presence of such ionized elements, helping depletion. Currently we are in a very dampened solar cycle, which keeps solar wind down, so ozone might run at higher concentrations in the polar stratosphere, hence the warming. There might be other mechanisms, but like I said before, I'm far from being an expert. But let's say that the stratosphere is "receptive".

So, we are probably in a very favorable state for high latitude blocking, and high amplitude waves disrupting and warming the PV had and probably will keep ridging forming in the high latitudes. I'm not expecting severe/continuous -AO/-NAO, it has to give sometimes, but overall a disturbed state will be favored as long as we keep those favorable feedbacks going.

BTW, looks like another high amplitude wave is making it's way. Let's see how strong it gets.

Thanks for the explanation. I presume that the early Dec wave will help us for late December, or would the affects be for January? Essentially what I'm asking is how would you go about monitoring these waves and their affects? Just monitor stratospheric temp charts and see if they show warming/PV disruption in the extended range?

[okie333]

Wave 1 is going to be amazingly high and either peaking or still rising in around 10 days according to the ECMWF.

Zonal winds weaken at the same time, day 10 especially weakens them... the +QBO may have an early (February or March or so) demise if the hyper-negativity in the equatorial upper stratosphere strengthens as much as the ECMWF is saying it will.