Let's talk ENSO

[weatherwiz]

1 hour ago, 40/70 Benchmark said:

Look how weak the positive anomalies are near S America...

Yeah great point. 

For La Nina's the focus was on 120°W to 170°W for anomalies.

Since EL Nino's tend to incorporate a larger swath of anomalies and also more into the N1.2 zone, may have to extend analysis through entire ENSO zone (180° to 80°W) and if core anomalies 160-180 call that West-Based, 160-120 Basin Wide, and 120-80 East-Based

[40/70 Benchmark]

25 minutes ago, weatherwiz said:

Yeah great point. 

For La Nina's the focus was on 120°W to 170°W for anomalies.

Since EL Nino's tend to incorporate a larger swath of anomalies and also more into the N1.2 zone, may have to extend analysis through entire ENSO zone (180° to 80°W) and if core anomalies 160-180 call that West-Based, 160-120 Basin Wide, and 120-80 East-Based

Bottom line is that its a judgement call at the end of the day...but there are very few events, especially ones that aren't really weak, that are entirely confined to a certain area...so I tend to judge by where the concentration of strongest anomalies is centered, not necessarily minimum el nino/la nina criteria.      

Its the stronger events in which structure is more important because forcing is more diffuse with greater variance in the weaker events, so you don't want to have such stringent criteria in distinguishing what can be pretty pivotal differences with respect to type classification.            

[weatherwiz]

On 1/3/2023 at 2:31 PM, 40/70 Benchmark said:

Bottom line is that its a judgement call at the end of the day...but there are very few events, especially ones that aren't really weak, that are entirely confined to a certain area...so I tend to judge by where the concentration of strongest anomalies is centered, not necessarily minimum el nino/la nina criteria.      

Its the stronger events in which structure is more important because forcing is more diffuse with greater variance in the weaker events, so you don't want to have such stringent criteria in distinguishing what can be pretty pivotal differences with respect to type classification.            

So after going back and assessing and taking your input, I've made the switches of the basin-wide to west-based for those years. I think before I may my list final, I want to do composites of OLR and see if that can help aid in any guidance. 

I also am thinking of coming up with a breakdown for SSTA's off the West Coast. There are a solid mixture of events with significant SSTA differences here and my inclination is that could be a significant player. The same can be said for Nina's. 

I was looking into the Trans-Nino Index, but TBH, I don't truly understand it and some breakdowns I was doing with it made zero sense. 

[weatherwiz]

Well here is a composite of all EL Nino temperature anomalies. Started to get rolling on EL Nino composites. 

[weatherwiz]

@40/70 Benchmark have you done your EL Nino composites yet? This is the breakdown I have using the Ensemble ONI and ONI. 

Note: On paper I do a breakdown of strong vs. super strong but in composites I group together (but may also do separate for composites)

[weatherwiz]

Considering the longer dataset of the ensemble ONI, I'm a bit concerned with the lack of weak events

[40/70 Benchmark]

On 1/7/2023 at 2:41 PM, weatherwiz said:

@40/70 Benchmark have you done your EL Nino composites yet? This is the breakdown I have using the Ensemble ONI and ONI. 

Note: On paper I do a breakdown of strong vs. super strong but in composites I group together (but may also do separate for composites)

No. I'll do it over the summer. I only go back to 1950.

[weatherwiz]

Well I've decided to go back and re-do my composites. Noticed a few things and made changes. It sucks b/c of all the work done, but the changes I think made sense. Anyways, I don't know why this didn't stick out to me before, but the La Nina of 1971-1972 was very interesting. It's one of the only ENSO events in which the core anomalies are displaced well outside of the equatorial region (5°N to 5°S). The only other ENSO event close happened a few years later (1974-1975).

This only caught my attention because I'm taking a stronger look at classifying structure and trying to develop a consistent "definition" and reasoning to back up the classification. I guess this would go down as East Based (which I had previously). 

[weatherwiz]

I am going to go back and re-start this whole project. What I need to do is create a documentation of I guess what you can call definitions, or guidelines, to establish as much consistency as possible. One thing I've learned when it comes to research is, there really is no right or wrong way as long as you're establishing criteria and consistency. Since this is dealing with ENSO I'll use ENSO as an example, but let's say I wanted to create a list of La Nina winter's and someone else did too. Based on what criteria we each choose, we may come up with different results. This doesn't mean one is wrong. 

As we know, when it comes to ENSO, there are two components, oceanic and atmospheric. When classifying ENSO or assessing ENSO (whether it be current state of predicted state), we solely turn to the oceanic aspect, sea-surface temperature anomalies. We can assess this via the Oceanic-Nino Index (ONI) which focuses on the 3.4 region. However, the atmospheric aspect of ENSO is just as important. So I want to really focus and incorporate this aspect as well. 

Before I create composites, I want to focus on the following:

1) ENSO phase classification (La Nina or EL Nino) - I will be using the CPC's Oceanic-Nino Index (ONI) and Eric Webb's Ensemble Oceanic-Nino Index EONI). The strength of incorporating the EONI is you have a much longer dataset to utilize with ENSO events going back to the late 1800's. This index also incorporates the numerous definitions which exist in classifying ENSO events. 

2) ENSO strength classification (Weak, Moderate, Strong/Super-strong) - The strength will based upon the peak strength of the event. The exception will be if the peak occurred in the late spring or summer months (which a few events meet). For events which are borderline in strength (as determined by the ONI/EONI) I will list that event in both. This will provide a measure to see how "well" that event fits in with other events in either strength. 

3) ENSO structure classification (West-Based, Basin-Wide, East-Based) - This is where when going back I noticed a lot of discrepancies in my original breakdowns. I re-created SSTA plots and re-created a list without looking at the original to see if the new list matched the original list. It did not. This told me I had no consistency with my classifications. So, with that, the new list focuses more heavily on where the core of the greatest anomalies were located. I think doing this broke up the basin-wide events a bit. I also found a few I classified as west when it was clearly east and vice versa. 

4) Atmospheric component - For this I will be heavily looking into SOI, MEI and even looking into BEST (Bivariate ENSO timeseries) and the TNI (trans-nino index). As I was starting this, my thinking was I could use the SOI and MEI to assist in the strength classification. However, I found there wasn't a strong correlation between these values and the strength (oceanic) of the ENSO event. After some thinking and reading it occurred to me, these indices can be used to help determine how coupled the ENSO event is (atmospheric-oceanic coupling). There are some weak La Nina's with relatively high SOI's and some stronger one's with lower SOI's. So you can have a weak event that is strongly coupled and a strong event that isn't. This can help identify events which may act more how you would "expect" the event to behave. 

In terms of composites, initially all the composites focused on DJF. That's fine and good and all, but all that does is provide an "average" of an entire season. This does absolutely nothing with illustrating transitions or periods of deviations - which at the end of the day is really what is most important with weather forecasting. 

I want to continue with DJF composites, but also do composites for the following breakdowns:

1) OND

2) DJF

3) NDJFM

4) Monthly (October, November, December, January, February, March) 

5) 6-week breakdowns 

 

[weatherwiz]

I also sent an email to PSL with a user enhancement suggestion. 

It would be PHENOMENAL if multiple composites can be downloaded at once. 

The way I do it is I create a composite, copy it, and paste it into a pain document. So if I'm doing weak La Nina winter temperature anomalies, I'll put in each year (one at a time) to make the composite then put into paint. This process is TEDIOUS and extremely time consuming. In reality, I'd never accomplish what I'm trying to do. Would have to work 24/7 on it lol

[weatherwiz]

Well I'm really hoping things will quiet down across the country in terms of winter weather soon so I can really get back into this. 

Anyways, I have started to go back and re-do this whole project. 

I have completed the list of La Nina winters by strength (weak, moderate, strong/super-strong).

When looking at structure (west-based, basin-wide, east-based), I want to go about this in a way that is a bit more complex. Originally, I was doing structure based on DJF SSTA's, however, I think structure evolution also needs to be taken into account. For example, you could have east-based during the fall and that could evolve into a west-based structure moving through winter. So for this, I am doing SSTA composites for OND, NDJ, and DJF. 

When I get into the core of the composites (500mb height anomalies, Sea-level pressure anomalies, temperature anomalies, Outgoing longwave radiation anomalies, etc.) I am going to break winter into two halves. 

December 1 - January 30 

February 1 - March 31

Doing this will now incorporate March into my composites which I didn't have before and obviously we know winter can be a tale of two halves. I think doing this breakdown too will elicit better signals of pattern change periods in the historical record. 

[weatherwiz]

It seems WAY mote difficult to classify structure of EL Nino (west, basin-wide, east) then it is for La Nina. 

[weatherwiz]

Well started making some "headway" with EL Nino composites. Below is a list of EL Nino winters I generated using Eric Webb's Ensemble ONI and the CPC's ONI.

I have yet to break down these events into strength b/c I'm not really sure what criteria to use. Majority of EL Nino events peak before the official winter season. Not sure if I want to do peak EL Nino strength or do the strength during the OND or DJF period. 

Also it's very challenging to do a structure breakdown...from my perspective anyways, the majority of EL Nino events look east-based, but that is using SSTA's. Maybe OLR would be a better proxy

[weatherwiz]

Strength breakdowns 

[weatherwiz]

Below are my composites for weak EL Nino, moderate EL Nino, and strong EL Nino winter's.

Weak EL Nino Winter's:

Moderate EL Nino Winter's:

Strong EL Nino Winter's:

[40/70 Benchmark]

28 minutes ago, weatherwiz said:

Below are my composites for weak EL Nino, moderate EL Nino, and strong EL Nino winter's.

Weak EL Nino Winter's:

Moderate EL Nino Winter's:

Strong EL Nino Winter's:

I'll do this is either May or June....after I do my seasonal post-mortem.

[weatherwiz]

1 minute ago, 40/70 Benchmark said:

I'll do this is either May or June....after I do my seasonal post-mortem.

I figure to get an early start now while the weather is quiet across the country  

All bets become off once Tropical season starts haha. 

but I am really struggling with the structure classification 

[40/70 Benchmark]

32 minutes ago, weatherwiz said:

I figure to get an early start now while the weather is quiet across the country  

All bets become off once Tropical season starts haha. 

but I am really struggling with the structure classification 

Topics will be dead until at least July...aside from a rouge system here of there. I'll be good to go by then.

[weatherwiz]

Well I am an idiot. I realize why I've struggled mightily with EL Nino structure. I went back to the drawing board starting off with the basics of EL Nino and its developing via references from NOAA, research papers, etc. When dealing with EL Nino structure, it's a completely different process then La Nina. With EL Nino you're either going to have EP (canonical) EL Nino (or EP to say central based) or your modoki (warming in the central or western ENSO regions. 

[weatherwiz]

I've gone back through my printout charts of SSTA evolution during EL Nino fall's and winter (OND, NDJ, and DJF). 

1. Using my strength breakdown list, I analyzed the SSTA evolution for weak, moderate, and strong events. 
2. I've categorized the evolution of each event (of similar strength) and grouped like categories. 
3. This yields the following

Note: when I say "weakened" I mean anomalies weakened through fall and winter. when I say "strengthened" I mean anomalies strengthened through fall into winter. 

Weak EL Nino Fall ---> Winter SSTA Evolution

1. EP (Anomalies did not expand or retrograde west)

2. Late blossoming EP (late blossoming EL Nino)

3. Modoki

4. EP (retrograding and weakening anomalies)

5. EP (Anomalies did not expand or retrograde west, but weakened)

6. EP (Core anomalies were located in the western ENSO region and weakened)

Moderate EL Nino Fall ------> Winter SSTA Evolution 

1. EP (Anomalies retrograded and weakened) 

2. EP (Anomalies did not retrograde or expand west, but weakened) 

3. EP (Anomalies expanded west)

4. EP (Expanded through basin and strengthened)*** (by definition this event was a strong one, but borderline so I may remove) 

5. Modoki 

Strong EL Nino Fall ----> Winter SSTA Evolution

1. EP (Extended through basin and weakened. Became modoki)

2. EP (Extended through basin)

3. EP (Extended through basin and weakened)

4. Modoki became EP

5. (Expanded through basin and strengthened) 

[weatherwiz]

Building on the above post the focus is going to shift in assessing OLR anomalies. While there of course is a relationship between SSTAs and convection, I don't think its as explicit where you can say "if core anomalies are east then tropical forcing is also east". 

[40/70 Benchmark]

On 4/16/2023 at 3:47 PM, weatherwiz said:

Well I am an idiot. I realize why I've struggled mightily with EL Nino structure. I went back to the drawing board starting off with the basics of EL Nino and its developing via references from NOAA, research papers, etc. When dealing with EL Nino structure, it's a completely different process then La Nina. With EL Nino you're either going to have EP (canonical) EL Nino (or EP to say central based) or your modoki (warming in the central or western ENSO regions. 

How so? I don't understand this post.

[weatherwiz]

4 minutes ago, 40/70 Benchmark said:

How so? I don't understand this post.

Maybe I am wrong on this, but one is how the event develops. Your typical EL Nino develops off the coast of South America and the warm anomalies will develop and expand westward across the equatorial Pacific. So really you either are going to have an east-based event or a modoki event (I don't think there really is a west-based event). La Nina's can develop anywhere within the basin and you can have your coldest anomalies west, basin, or east (and of course you have your modoki). 

 

[40/70 Benchmark]

37 minutes ago, weatherwiz said:

Maybe I am wrong on this, but one is how the event develops. Your typical EL Nino develops off the coast of South America and the warm anomalies will develop and expand westward across the equatorial Pacific. So really you either are going to have an east-based event or a modoki event (I don't think there really is a west-based event). La Nina's can develop anywhere within the basin and you can have your coldest anomalies west, basin, or east (and of course you have your modoki). 

 

I don't know, it seems like you're over analyzing to a degree...I don't really focus on the origin. I couldn't care less what the event looks like during the summer. But I guess I will be able to speak more to this after I do my el nino groupings.

[weatherwiz]

4 minutes ago, 40/70 Benchmark said:

I don't know, it seems like you're over analyzing to a degree...I don't really focus on the origin. I couldn't care less what the event looks like during the summer. But I guess I will be able to speak more to this after I do my el nino groupings.

Well it's not so much what the event looks like during the summer, but moreso how the event is evolving moving through the fall. 

For my composites I did when it came to SST's, OLR, and SLP I did composites for DJFM, OND, NDJ, and DJF to assess how each of these events evolved through the fall. 

 

[40/70 Benchmark]

40 minutes ago, weatherwiz said:

Well it's not so much what the event looks like during the summer, but moreso how the event is evolving moving through the fall. 

For my composites I did when it came to SST's, OLR, and SLP I did composites for DJFM, OND, NDJ, and DJF to assess how each of these events evolved through the fall. 

 

I guess I just feel as though that is superfluous....but to each their own. It will be interesting to look at, anyway. I am going to focus on peak period and DJFM.

[weatherwiz]

9 minutes ago, 40/70 Benchmark said:

I guess I just feel as though that is superfluous....but to each their own. It will be interesting to look at, anyway. I am going to focus on peak period and DJFM.

It is quite tedious making so many different composites. I only did those breakdowns for those variables mentioned. When it came to temperatures and 500mb height anomalies I just focused on DJFM. 

I think though for composites I'm only going to focus on 500mb height anomalies, temperature anomalies, OLR anomalies, SLP anomalies, and precipitation anomalies. I already have pretty much all these done (except for precipitation). 

I'm highly debating creating a website too where I can post these composites (especially the GIFs) so it will be easier to assess. 

[40/70 Benchmark]

49 minutes ago, weatherwiz said:

It is quite tedious making so many different composites. I only did those breakdowns for those variables mentioned. When it came to temperatures and 500mb height anomalies I just focused on DJFM. 

I think though for composites I'm only going to focus on 500mb height anomalies, temperature anomalies, OLR anomalies, SLP anomalies, and precipitation anomalies. I already have pretty much all these done (except for precipitation). 

I'm highly debating creating a website too where I can post these composites (especially the GIFs) so it will be easier to assess. 

Do you debate with yourself aloud? (Looks left) "Paul, make a website for those OLR anomalies" (Looks right) "No way, Paul, too much work!"

You may be in a strait jacket by the time el nino is declared lol

[weatherwiz]

18 minutes ago, 40/70 Benchmark said:

Do you debate with yourself aloud? (Looks left) "Paul, make a website for those OLR anomalies" (Looks right) "No way, Paul, too much work!"

You may be in a strait jacket by the time el nino is declared lol

 

That's pretty close to how it goes 

[Ginx snewx]