ENSO Discussion

[Phil]

The +AAM in the subtropics has persisted in spite of more than one bout of enhanced IO convection, it should not be dismissed solely as high frequency noise because if it was mostly subseasonal variability, the anomaly would have eroded already.

Of course, the integral and spatial balance of the AAM budget reflects a multitude of components (both high and low frequency). The spatial structure of the AAM budget right now (surplus in the low-latitudes, etc) does reflect the slow evolution into +ENSO and the mode of shear stress/momentum deposition associated with the QBO structure as well.

 

However, higher frequency, pseudo-resonant components (IE: cycles of meridional transfer/MT, MJO, etc) also express in the AAM budget/tendencies. And the timing/amplitude of these behaviors also loops in interference with ENSO on both sides of the coin.

 

For the time being, this is an episode of destructive interference. If the current frequency holds, this will dissociate in a few weeks, and we’ll move into a regime of constructive interference towards Thanksgiving.

[Phil]

"However, I’m vehemently opposed to the idea that the higher frequency interference “teleconnects” to the ENSO/lower frequency modes beneath it, because there is a strong inverse relationship in their power spectras. An active MJO/intraseasonal cycle dynamically opposes a stronger ENSO state at this point in the seasonal cycle."

 

This relationship is true for many reasons that aren't physically related to what you're describing here but rather are artifacts. One good example is how advection by the stronger background flow and alterations in convective distribution, especially in areas that traditionally observe more during El Ninos narrows the MJO's bandwidth s.t. it shifts to higher frequency, eastward propagating Kelvin modes. When you actually boil it down, this doesn't explicitly say anything about the amplitude of the totality of subseasonal variability but rather that the shift of the MJO towards Kelvin Waves gives the illusion of "weaker" MJO activity when reality doesn't necessarily corroborate this.

But what you’re describing is a change in the higher frequency power spectra, correct?

 

This is, in fact, a dynamic expression of the change in amplitude (if you’re okay with summarizing it from that order of evolution).

[Webberweather53]

But what you’re describing is a change in the higher frequency power spectra, correct?

 

This is, in fact, a dynamic expression of the change in amplitude (if you’re okay with summarizing it from that order of evolution).

 

Well it's a dynamic change in amplitude at the lower end of the MJO's spectra but that does not mean the higher frequency version of eastward subseasonal convective variability during El Ninos isn not as much of an "MJO" as lower frequency counterpart that's more often expressed in La Ninas.

 

What I'm trying to say is that both are essentially different expressions for the exact same phenomena on opposing ends of the subseasonal continuum. While the character of the MJO specifically changes in the face of ENSO, it's hard to argue the same for amplitude because the MJO is partially a function of how we define it in time-frequency space. The blue shift during +ENSO leads to a portion of the MJO's variance leaking into Kelvin phase space, outside the entirely arbitrary bounds we've chosen to measure it. The MJO is only one component of subseasonal variability, losses in its apparent (but potentially non-physical) amplitude actually doesn't describe how the totality of other phenomena which often pick up a considerable amount of the remaining slack in particular areas of the globe. 

[Webberweather53]

Of course, the integral and spatial balance of the AAM budget reflects a multitude of components (both high and low frequency). The spatial structure of the AAM budget right now (surplus in the low-latitudes, etc) does reflect the slow evolution into +ENSO and the mode of shear stress/momentum deposition associated with the QBO structure as well.

 

However, higher frequency, pseudo-resonant components (IE: cycles of meridional transfer/MT, MJO, etc) also express in the AAM budget/tendencies. And the timing/amplitude of these behaviors also loops in interference with ENSO on both sides of the coin.

 

For the time being, this is an episode of destructive interference. If the current frequency holds, this will dissociate in a few weeks, and we’ll move into a regime of constructive interference towards Thanksgiving.

 

When the +AAM subtropical anomaly persists through multiple subseasonal forcing cycles, it clearly shows that the low frequency support (from ENSO) is stronger than subseasonal state-dependent noise that tries to occasionally destroy and interfere w/ it. Therefore, what we're seeing is indeed an expression of ENSO in the atmosphere, as I mentioned earlier. The +AAM subtropical anomaly developed in late September and if we assume you were right and that this is  just some high frequency noise, it should have decayed following the round of IO convection in early October, but it persisted and has since intensified. 

 

 

http://www.atmos.albany.edu/student/ventrice/real_time/timeLon/vp.anom.30.5S-5N.gif

[Guest daniel1]

Of course, the integral and spatial balance of the AAM budget reflects a multitude of components (both high and low frequency). The spatial structure of the AAM budget right now (surplus in the low-latitudes, etc) does reflect the slow evolution into +ENSO and the mode of shear stress/momentum deposition associated with the QBO structure as well.

 

However, higher frequency, pseudo-resonant components (IE: cycles of meridional transfer/MT, MJO, etc) also express in the AAM budget/tendencies. And the timing/amplitude of these behaviors also loops in interference with ENSO on both sides of the coin.

 

For the time being, this is an episode of destructive interference. If the current frequency holds, this will dissociate in a few weeks, and we’ll move into a regime of constructive interference towards Thanksgiving.

What’s constructive interference?

[Jesse]

What’s constructive interference?

The opposite of what you are doing when you attack Jim’s posts.

[luminen]

What’s constructive interference?

             

[snow_wizard]

At this point I'm thinking an early peak for ENSO SSTs probably averaging out to warm neutral or very weak Nino for the winter.  We can do well with that.

[Phil]

Well it's a dynamic change in amplitude at the lower end of the MJO's spectra but that does not mean the higher frequency version of eastward subseasonal convective variability during El Ninos isn not as much of an "MJO" as lower frequency counterpart that's more often expressed in La Ninas.

Of course. But strong ENSOs (niño and niña) both see a reduction in the total amplitude in the power spectra which are higher than their own. Of course you have to factor in climo because the raw frequencies always increase with eastward propagation away from the warm pool.

 

But to argue that high amplitudes in the intraseasonal frequencies are constructive to ENSO seems strange to me..otherwise they’d present as red noise with respect to time/frequency, not blue noise.

 

Or maybe I’m misinterpreting you?

[Phil]

When the +AAM subtropical anomaly persists through multiple subseasonal forcing cycles, it clearly shows that the low frequency support (from ENSO) is stronger than subseasonal state-dependent noise that tries to occasionally destroy and interfere w/ it. Therefore, what we're seeing is indeed an expression of ENSO in the atmosphere, as I mentioned earlier. The +AAM subtropical anomaly developed in late September and if we assume you were right and that this is just some high frequency noise, it should have decayed following the round of IO convection in early October, but it persisted and has since intensified.

 

 

http://www.atmos.albany.edu/student/ventrice/real_time/timeLon/vp.anom.30.5S-5N.gif

Of course, I agree the AAM integral in the 30N/30S domain is an expression of ENSO.

 

But since we’re talking about constructive/destructive interference, I think it’s important to note the poleward propagation of +AAM there, and recall how it relates to the deposition of momentum in the tropics (better expressed via the derived tendency of AAM rather than the integral of AAM, in my opinion).

 

To me, this reflects a switch to destructive interference on an intraseasonal scale as we leave October and progress into mid-November. Thereafter, assuming we stay on this course, it looks more niño-ish in December.

[Webberweather53]

CDAS finally caught up to the weekly OISSTv2 product which showed >+1C anomalies last week and SST anomalies are now above or well above +1C in a large portion of the central equatorial Pacific. Like I said before, we're already entering an El Nino regime and a moderate event is possible. 

 

[TigerWoodsLibido]

CDAS finally caught up to the weekly OISSTv2 product which showed >+1C anomalies last week and SST anomalies are now above or well above +1C in a large portion of the central equatorial Pacific. Like I said before, we're already entering an El Nino regime and a moderate event is possible.

 

Oh well...onto 19-20 or maybe even 20-21

[TT-SEA]

Oh well...onto 19-20 or maybe even 20-21

 

 

If this Nino keeps strengthening... it might reduce the chances of a Nino next year.

 

And with low solar... we very well good have some fun this winter even with a Nino.

[Phil]

Perhaps I’ve blown a mental gasket, but I’m still not convinced this will meet official criteria for a niño (by ONI). Or if it does, I think it will be borderline.

[AbbyJr]

Does anybody on here think El Nino has peaked or is currently peaking? if so, why? And if not, this Nino could end being moderate-strong? SST's in the 3.4 region are 1.3C!

 

[OKwx2k4]

Perhaps I’ve blown a mental gasket, but I’m still not convinced this will meet official criteria for a niño (by ONI). Or if it does, I think it will be borderline.

Phil, I've been holding the exact same song since probably springtime as well. I'll be shocked if we make official criterion.

[Esquimalt]

Phil, I've been holding the exact same song since probably springtime as well. I'll be shocked if we make official criterion.

I sure hope you two are right.  That spells best for the western winter!

[AbbyJr]

Phil, I've been holding the exact same song since probably springtime as well. I'll be shocked if we make official criterion.

Unless this Nino is planning on turning moderate-strong, or levelling off and staying where its at, then it has likely peaked and will only weaken from here on in. Certainly it doesn't normally peak this early, but it can still happen. In fact, El Nino peaked super early in 2002/2003. I'm hoping it has, and we start to see the SST's drop throughout November.

[TigerWoodsLibido]

Unless this Nino is planning on turning moderate-strong, or levelling off and staying where its at, then it has likely peaked and will only weaken from here on in. Certainly it doesn't normally peak this early, but it can still happen. In fact, El Nino peaked super early in 2002/2003. I'm hoping it has, and we start to see the SST's drop throughout November.

Yeah, let's go ahead and avoid anything associated with 02-03 pls.

[OKwx2k4]

Unless this Nino is planning on turning moderate-strong, or levelling off and staying where its at, then it has likely peaked and will only weaken from here on in. Certainly it doesn't normally peak this early, but it can still happen. In fact, El Nino peaked super early in 2002/2003. I'm hoping it has, and we start to see the SST's drop throughout November.

Longevity of Nino and placement/nature like 2009 with peak like 2002-2003 is really where the idea and primary thought came from, along with some hints from the late 70s and 1911, so I can say we're probably staying on course with that camp.

[OKwx2k4]

I sure hope you two are right. That spells best for the western winter!

Semi-true in my opinion. There is a part of the NE pac pattern that throw wrenches that we don't expect when there's that much warmth up there. Diminished Niño strength from here on is nothing but a win for you folks though.

[AbbyJr]

Yeah, let's go ahead and avoid anything associated with 02-03 pls.

 

Sorry but it was the only example I could find of an El Nino peaking super early.

[AbbyJr]

Really interesting thing going on with the SST's right now. Nino 3 and 4 are significantly cooler then Nino 3.4, but Nino 3 is warmer then 4. Nino 4 is also dropping and Nino 3 and 3.4 are rising. Whats going on here? Could this be a modoki or east based El Nino? Or are these just daily fluctuations that have no relevance?

 

 

 

[Phil]

Trades along/west of the dateline and westerlies east of there, thanks to the intraseasonal IO forcing.

 

Destructively interferes with the +ENSO base state, but will dissociate into a more west-based +ENSO-like state again after Thanksgiving.

[Phil]

Sorry but it was the only example I could find of an El Nino peaking super early.

I’d argue 1987/88 is the best example of an early-peaking niño. However, it was a 2nd year event with increasing solar, unlike this year.

[BLI snowman]

I’d argue 1987/88 is the best example of an early-peaking niño. However, it was a 2nd year event, unlike this year. Also had increasing solar.

 

Could be something similar next year if this Nino manages to sustain itself a bit and then re-blossom next summer. And then a nosedive into strong Nina territory in 2020-21.

[Phil]

Could be something similar next year if this Nino manages to sustain itself a bit and then re-blossom next summer. And then a nosedive into strong Nina territory in 2020-21.

That’s what I was thinking too, assuming this one doesn’t get torpedoed by an upwelling OKW before then (seems unlikely at this point, given the off-climo timing/amplitude of the ongoing wavecycle, but who knows?).

 

And the big kahuna is the fact that the solar cycle/IPWP response will definitely favor a strong La Niña in the early 2020s. The question is, does it happen in 2020/21 or 2021/22? Or both? At least one of those 2 years is going to go -ENSO in a big way.

[AbbyJr]

Trades along/west of the dateline and westerlies east of there, thanks to the intraseasonal IO forcing.

 

Destructively interferes with the +ENSO base state, but will dissociate into a more west-based +ENSO-like state again after Thanksgiving.

 

So you think we will move back into a west based El Nino after Thanksgiving? And do you think this sudden spike in the 3.4 regions means we could be dealing with a moderate El Nino this winter instead of the earlier predictions of a weak event?

[Phil]

So you think we will move back into a west based El Nino after Thanksgiving? And do you think this sudden spike in the 3.4 regions means we could be dealing with a moderate El Nino this winter instead of the earlier predictions of a weak event?

Well, I’m not sure it’s really changed..short term variations in the ENSO SSTs by longitude is commonplace.

 

As for ENSO strength, I think it peaks this month and then steps downward. In the end, my guess is either weak niño or warm neutral by the official definition for such events by ONI.

[AbbyJr]

Well, I’m not sure it’s really changed..short term variations in the ENSO SSTs by longitude is commonplace.

 

As for ENSO strength, I think it peaks this month and then steps downward. In the end, my guess is either weak niño or warm neutral by the official definition for such events by ONI.

Cool, what are the factors that makes you think El Nino peaks this month?

[Guest daniel1]

Trades along/west of the dateline and westerlies east of there, thanks to the intraseasonal IO forcing.

 

Destructively interferes with the +ENSO base state, but will dissociate into a more west-based +ENSO-like state again after Thanksgiving.

Will it become more favourable to make the Niño more west based after T-giving ?

[Webberweather53]

You've definitely blown a mental gasket if you don't think this has a chance to become an El Nino, this isn't the "slow-walk" some were expecting because it's obvious we're already in an El Nino like I've been saying for weeks, NINO 3.4 anomalies are now near +1.5C. No amount of hand-wringing over thresholds can make that go away.

[Geos]

Crap, it's still going up.

 

[TT-SEA]

Crap, it's still going up.

 

 

 

We need an 'unlike' button.      That really does suck.

[TT-SEA]

Appears to be west-based... not sure if that is good or bad.    

 

And that warm pool off our coast keeps growing too.

 

[Esquimalt]

Appears to be west-based... not sure if that is good or bad.    

 

And that warm pool off our coast keeps growing too.

 

Yeah that warm pool doesn't spell anything good.  But what are some examples of some west based ninos?

[Kayla]

Seems to me that the "official" CPC ONI reading should be solidly El Nino by the SON reading.

 

This winter looks to officially go down as an "El Niño Winter" no matter how you spin it.

[TT-SEA]

Yeah that warm pool doesn't spell anything good.  But what are some examples of some west based ninos?

 

 

I don't know... but its been discussed on here before.   Phil will know.

[Esquimalt]

Seems to me that the "official" CPC ONI reading should be solidly El Nino by the SON reading.

 

This winter looks to officially go down as an "El Niño Winter" no matter how you spin it.

I agree with you.  I don't know how it can fall after this.  

[Phil]

You've definitely blown a mental gasket if you don't think this has a chance to become an El Nino, this isn't the "slow-walk" some were expecting because it's obvious we're already in an El Nino like I've been saying for weeks, NINO 3.4 anomalies are now near +1.5C. No amount of hand-wringing over thresholds can make that go away.

Well that depends what parameters you use to define “slow walk”..SSTAs aren’t a good way to diagnose that. The anomalous suppression of the thermocline has not amplified drastically over the last six months..it’s been suppressed for awhile. If we were observing a coherent amplification of the ENSO wavecycle then I’d be on the moderate/strong niño train as well. But that’s not the case.

 

I’m going to write up a detailed post on this later, but I’m still going with a borderline event as reflected by the trimonthly ONI from SON to JFM.