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Teleconnections: A More Technical Discussion

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3 hours ago, Isotherm said:

 

 

 

 

 

First, I want to thank Tams @Tamara for that absolutely phenomenal post on the previous page - excellent recapitulation of the pertinent processes.

 

Secondly, I wish to reprise to readers what the original point of debate was: the uncharacteristically high AAM surge for this weak El Nino (similar to strong El Ninos). Specifically, why is this the case? To review, I hypothesized that one possible, viable pathway could be off-equator and non-ENSO region SST's which force changes in zonal wind anomalies and consequently global atmospheric angular momentum.

 

Eric, you're comparing apples to oranges with those years ranges. I believe it's much more pertinent to subtract the pre 1980 El Nino events from the post 1980 El Nino events, as what we're truly juxtaposing here is the alteration in off-equator SST warmth that aids in zonal wind changes.

 

And consequently, if we create the composite in the more pertinent manner, in my view, the result is nearly opposite to your composite. 

 

Note the stronger zonal winds in the sub-tropical belt 30 N reflected by the oranges, redolent of the fact that recent El Ninos have seen an increase in sub-tropical zonal winds and thus likely AAM compared to older years.

 

345mwbn.png

 

 

 

This isn't an apples-oranges comparison, I chose to keep my years within the satellite era because upper tropospheric data can be pretty sketchy before the mid-late 1970s, but in any case it's pretty obvious that your interpretation of the corresponding SST composite couldn't have been any further from reality!  Btw, if you're trying to detect a base state change in AAM due to the background climate, it would be more pertinent to include all years instead of El Ninos only so as to limit internal variability and sampling issues. Your above composite if anything is actually an apples-oranges comparison! You need to be aware of the fact that 3 of the 4 strongest El Ninos since 1950 occurred in the first group your subtracting from (1982-83, 1997-98, & 2015-16) and they're likely heavily skewing the results in your composite to show +AAM ~30-40N & thus the set of years you're subtracting from has significantly stronger El Ninos in it. If your goal was to showcase base state changes in a particular ENSO phase from observations, good luck with that because internal variability is too large for an analysis like this until the sample size of events for both groups exceeds 30-40 (& this isn't simply determined from basic statistics, several papers have also noted this to be a sufficient sample size s.t. ENSO signals become larger than internal varaibility, Garfinkel has some nice work on this topic).

 

The above composite doesn't line up with this year either, notice how the +AAM is poleward of 30N whereas this year it's been below this latitude. That seems trivial superficially but it actually matters a lot here considering that the half-width of the concomitant circulation anomalies are on the order of the difference between these "modern" Ninos and this year. 

 

What you're showing only supports my earlier claims, and it's a reflection of similar base state response towards Hadley Cell expansion in fact! Only difference is the HC contracts more in El Nino years due to angular momentum deposition at the equatorward flank of the waveguide so the excess westerly momentum is still poleward of canonical NINO, but migrating poleward at a lower latitude than it would in La Ninas. 

 

It also really doesn't matter what start & end year I chose for my composite, there's a definitive long-term trend towards subtropical -AAM esp ~30N after the 1997-98 super NINO, which is completely different from what we're seeing this year. In fact, what we're seeing now is a temporary throwback to a cooler base state climate w/ contracted HC thus subtropical +AAM would be expected with tropical warming and subtropical cooling, if anything.

 

Here, I've blown up the original AAM time series plot and clearly marked the post 1997-98 subtropical -AAM that's corresponded with the aforementioned warming in the subtropics which completely flies in the face of what you've been trying to claim.

 

1516872957_ScreenShot2018-11-30at1.png.2cbd4e6af8887976ab3937d659488fca.png

 

 

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"Note the stronger zonal winds in the sub-tropical belt 30 N reflected by the oranges"

Once again, your interpretation is just flat-out wrong if you actually more closely inspected the data. Latitudinal averages of the zonal mean wind anomalies show anomalous easterlies in the subtropics ~20-30N in modern El Ninos. I recommend using cross-section analyses in NCEP R1, looks can be deceiving from standard difference plots.

 

08pY9sLzfd.png.f0456223b7be4bad6db86b1c82e08ad0.png

 

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2 hours ago, Isotherm said:

 

 

"it's quite mind-boggling to read unequivocal, unqualified, dogmatic statements such as, "you're wrong," as if the putative final word has been uttered."

 

Let's get a few things straight...

 

You stated on multiple occasions that there was excess westerly momentum in the long-term signal in the subtropics, I dismantled this proposal multiple times.


First the SST composite I responded to you with was supposedly indicative of +AAM in the subtropics. 

 

"This, in my view, corroborates the notion that zonal wind anomalies, off-equator, would be enhanced via strengthening meridional thermal gradients, and by extension, provide additional momentum injection into the atmosphere. "

 

Then of course, this same composite you referred to had -AAM in the same locations you assumed it would be positive. Oops...

MG3h5cx0Vh.png.178c746c820386460ad10d29c1fd4bb2.png.9e651f14560e0017f59692d6721e3a64.png

 

 

Then you then went onto claim that I was somehow cherry picking the data and should use post 1976 NINOs to compare with that apparently showed excess subtropical +AAM.

 

"Eric, you're comparing apples to oranges with those years ranges."

 

"Note the stronger zonal winds in the sub-tropical belt 30 N reflected by the oranges, redolent of the fact that recent El Ninos have seen an increase in sub-tropical zonal winds and thus likely AAM compared to older years."

 

Yet, once again you were wrong in this regard because there was -AAM in the NCEP R1 means ~20-30N in the difference composite. There's nothing dogmatic or unqualified about this, in fact I was looking at the EXACT same data you were.

 

The biggest difference is unlike what you did, I didn't just eyeball the composites and assume my opinion was right based on that highly subjective analysis. 

The actual data doesn't lie and shows that there's -AAM (in blue) in the subtropics in those same NINOs you said had +AAM, that is a fact, there is no debate on this particular point even though you're trying to make it look like there is.

 

08pY9sLzfd.png.f0456223b7be4bad6db86b1c82e08ad0.png.e11c02dfac1d9ce4e93b8bcba07653e1.png

 

 

In spite of how much you decided to wrongfully/childishly frame my responses to you as "unqualified" or "dogmatic" , it's an undeniable fact that your interpretations up to this point in time have been quite frankly wrong, whether you actually want to admit that or not is another story.

 

It's truly "mind-boggling" how someone could be so wrong especially with basic interpretations like these yet fail to realize what's been starting them in the face the entire time. That's aside from the fact that this discussion was pretty civil and intellectually stimulating up until this point when you decided to instigate in nonsensical attacks like these.

 

This is the last I'm going to say on this matter.

 

 

 

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1 hour ago, Webberweather said:

 

"it's quite mind-boggling to read unequivocal, unqualified, dogmatic statements such as, "you're wrong," as if the putative final word has been uttered."

 

Let's get a few things straight...

 

You stated on multiple occasions that there was excess westerly momentum in the long-term signal in the subtropics, I dismantled this proposal multiple times.


First the SST composite I responded to you with was supposedly indicative of +AAM in the subtropics. 

 

"This, in my view, corroborates the notion that zonal wind anomalies, off-equator, would be enhanced via strengthening meridional thermal gradients, and by extension, provide additional momentum injection into the atmosphere. "

 

Then of course, this same composite you referred to had -AAM in the same locations you assumed it would be positive. Oops...

MG3h5cx0Vh.png.178c746c820386460ad10d29c1fd4bb2.png.9e651f14560e0017f59692d6721e3a64.png

 

 

Then you then went onto claim that I was somehow cherry picking the data and should use post 1976 NINOs to compare with that apparently showed excess subtropical +AAM.

 

"Eric, you're comparing apples to oranges with those years ranges."

 

"Note the stronger zonal winds in the sub-tropical belt 30 N reflected by the oranges, redolent of the fact that recent El Ninos have seen an increase in sub-tropical zonal winds and thus likely AAM compared to older years."

 

Yet, once again you were wrong in this regard because there was -AAM in the NCEP R1 means ~20-30N in the difference composite. There's nothing dogmatic or unqualified about this, in fact I was looking at the EXACT same data you were.

 

The biggest difference is unlike what you did, I didn't just eyeball the composites and assume my opinion was right based on that highly subjective analysis. 

The actual data doesn't lie and shows that there's -AAM (in blue) in the subtropics in those same NINOs you said had +AAM, that is a fact, there is no debate on this particular point even though you're trying to make it look like there is.

 

08pY9sLzfd.png.f0456223b7be4bad6db86b1c82e08ad0.png.e11c02dfac1d9ce4e93b8bcba07653e1.png

 

 

In spite of how much you decided to wrongfully/childishly frame my responses to you as "unqualified" or "dogmatic" , it's an undeniable fact that your interpretations up to this point in time have been quite frankly wrong, whether you actually want to admit that or not is another story.

 

It's truly "mind-boggling" how someone could be so wrong especially with basic interpretations like these yet fail to realize what's been starting them in the face the entire time. That's aside from the fact that this discussion was pretty civil and intellectually stimulating up until this point when you decided to instigate in nonsensical attacks like these.

 

This is the last I'm going to say on this matter.

 

 

 

Interesting trend on the plot. -AAM in the subtropics & +AAM in the polar jet area. Guessing that can be chalked up to the slow weakening of the HC which leads to that exact thing happening. 

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1 hour ago, Daimon said:

Can I get any article about deep stratospheric warming DSW ?

 

Hi @Daimon, welcome to 33.  We have loads of papers on SSWs in the Research Portal  including the very recent one that you are looking for which introduces the new "DSW" classification:  Sudden Stratospheric Warmings – developing a new classification based on vertical depth, applying theory to a SSW in 2018, and assessing predictability of a cold air outbreak following this SSW

 

Just click on the title for a direct link to the portal entry and the abstract. From there you will find a direct link to the full paper that Malcolm @Blessed Weather placed in there on November 2nd.  Check out the index while you are there for all the SSW and Stratosphere related papers:  https://www.33andrain.com/topic/996-index-to-papers-and-articles/   David :) 

 

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This doesn't look so good at all. Look at that positive EPO, More of a negative PNA as well, WPO way up as well and a positive NAO. 4indices.png

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3 hours ago, leo1000 said:

This doesn't look so good at all. Look at that positive EPO, More of a negative PNA as well, WPO way up as well and a positive NAO. 4indices.png

Appears to be the general time when there are some signals for some modest ridging in the area

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Dtb9lPRXQAAeDqv.jpg

 

Interesting look here no?

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Warm at the top layers first then downwelling? Am I seeing this right or is it the opposite?

Thanks Mugs

DtcNKzfWoAA859J.jpg

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I concede that there may be a bit of a spike in AAM around the 12th, but the overwhelming trend will be downward to the 20th.

 

IMG_5852.PNG

 

We haven't seen a significant -AAM tendency as of yet, and this would be expected after a big -FT (perhaps a week's lag to the extratropics). I am not sold on the significant +MTs personally, but time will tell. Looks like a lot of westerly momentum that doesn't match the pattern I am seeing.

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1 hour ago, Isotherm said:

 

That's a lot of +MT too soon. I'm not buying it.  I can see a bit of a +MT, but not enough to make another +AAM peak for the year.

 

There's been no cycle. It doesn't seem to fit within the GSDM. Maybe I'm wrong however, clearly this Nino has made some extra-ordinary statements. 

 

That being said, the FT is coming back up, but it would certainly be too early for the MT to be coming back on that. It just seems too early and out of place for me. The impacts of the FT drop should be felt 20 days later in CONUS. 25 Nov - 3 Dec ish, so 15-23 Dec. This is if the extratropics don't turn into a Niño centric mess.

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