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Let's Talk About SSW's as We Watch One Unfold


Eduardo

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1 hour ago, thunderbolt said:

Is there a difference between a ssw during a la Nina versus a ssw in a El Nino

Well, SSWs are more common during El Ninos because the El Nino causes enhanced ozone transport to the North Pole via the Brewer-Dodgson Circulation. 

Low ozone is a common condition of La Ninas, which makes it harder to warm the stratosphere effectively. 

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1 hour ago, nzucker said:

Well, SSWs are more common during El Ninos because the El Nino causes enhanced ozone transport to the North Pole via the Brewer-Dodgson Circulation. 

Low ozone is a common condition of La Ninas, which makes it harder to warm the stratosphere effectively. 

Ok thank you for your response

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On 2/6/2018 at 3:13 PM, donsutherland1 said:

If the vortex splits, that development would more likely favor Eurasian than North America. Still, the GEFS are hinting that the AO could plunge toward the end of the 15-day forecast period, so we'll see what happens.

Looks like this is the case. Indexes are holding steady in keeping cold air away from the US east coast (except for some quick shots). Storms will likely go to west of the big cities, giving them rain. I would love to hear Dr. Judah Cohen's latest thoughts though.

 

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6 hours ago, Wannabehippie said:

Looks like this is the case. Indexes are holding steady in keeping cold air away from the US east coast (except for some quick shots). Storms will likely go to west of the big cities, giving them rain. I would love to hear Dr. Judah Cohen's latest thoughts though.

 

I agree. Despite the EPS signal of strong blocking within 10-15 days, caution is likely in order. The EPS performed horribly at a similar timescale, completely missing the current AO+ regime.

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https://ams.confex.com/ams/21Fluid19Middle/webprogram/Paper317541.html

12.2 Teleconnection between Madden Julian Oscillation and Sudden Stratospheric Warmings

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Thursday, 29 June 2017: 10:45 AM
Salon G-I (Marriott Portland Downtown Waterfront)
Wanying Kang, Harvard University, Cambridge, MA; and E. Tziperman

 

Sudden Stratospheric Warming (SSW) events influence the Arctic Oscillation and mid-latitude extreme weather. Observations show SSW events to be correlated with certain phases of Madden Julian Oscillation (MJO), but the teleconnection mechanism, its planetary wave propagation path and the teleconnection time scale are still not well understood. We study the Arctic stratosphere response to MJO forcing using two models. First, a comprehensive General circulation model (the Whole Atmosphere Circulation Model, WACCM) with standard and enhanced convection entrainment rate leading to stronger MJO. Second, an idealized dry dynamical core with and without idealized MJO-like forcing. We show that the frequency of SSW events increases significantly, and that the averaged polar cap temperature therefore increases significantly in response to stronger MJO forcing. Consistent with previous studies, we find that heat transport by stationary waves is a major contributor to the SSW response. We also find that MJO-forced transient waves propagate at about 70 mb toward the Arctic, and then travel toward the upper stratosphere, then leading to the stationary wave response. The cleaner results possible with the idealized model allow us to identify that the propagation time is of the order of 40-60 days, significantly longer than implied by previous studies. The horizontal propagation path is influenced by zonal jet exit regions, again in agreement with previous studies of remote tropospheric effects of MJO-forced planetary waves. Given that MJO is predicted to be stronger in global warming scenario, these results suggest that SSW events may become more frequent in a future warm climate, possibly with all the implications this has on tropospheric high latitude weather.
flag.png - Indicates paper has been withdrawn from meeting
blue_ribbon.png - Indicates an Award Winner
 

http://onlinelibrary.wiley.com/doi/10.1002/2015GL066984/full

Finally, we reexamine the relationship between SST anomalies and MJO activity based on the historical record. Previously, Hendon et al. [1999] showed enhanced MJO activity, both globally and locally in the western/central Pacific, favored by positive SST anomalies in the central Pacific equatorial region around 160°E–160°W during November–March (their Figure 10). 

 
 
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+2000dm heights at 10mb 2-11/12. The record is a 20 period in 1965-66 I think with near +2000 mean 

I've seen a few Stratosphere warmings and models always go super ridiculous on -NAO 10+ days. I think they don't verify as strong

There is a difference in La Nina and El Nina. I found SSWs were much less likely to occur in La Nina but don't remember the effect differences, something like 2.5/1

-NAO likely +15 days but this Winter there is so much mid-latitude warming you have to wonder if it will itself pump the SE ridge in reverse -PNA. probably

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