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Let's talk ENSO


weatherwiz
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Weak East-Based La Nina Winter (DJF) Outgoing Longwave Radiation Anomalies (Using Ensemble ONI + ONI):

1338997768_WEAKEA1.GIF.a00617c5dca99119d85a9291e9bf5114.GIF

Moderate East-Based La Nina Winter (DJF) Outgoing Longwave Radiation Anomalies (Using Ensemble ONI + ONI):

1842273767_MODERA1.GIF.7fb4d48a7bc08d38bfc7daba9f1ed854.GIF

Strong/Super Strong East-Based La Nina Winter (DJF) Outgoing Longwave Radiation Anomalies (Using Ensemble ONI + ONI):

1769428075_StrongandSuperStrongEastBasedLaNinaWinterOLRAnomalies.gif.9c786b6ee7dfb64a6c4715551dbcc756.gif

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Weak Basin-Wide La Nina Winter (DJF) Outgoing Longwave Radiation Anomalies (Using Ensemble ONI + ONI):

952191486_WeakBasinWideLaNinaWinterOLRAnomalies.gif.d1b56fe8154e223dade00403cdad8ceb.gif

Moderate Basin-Wide La Nina Winter (DJF) Outgoing Longwave Radiation Anomalies (Using Ensemble ONI + ONI):

1189093109_ModerateBasinWideLaNinaWinterOLRAnomalies.gif.bfcd30cbe101cad6b84fdb74aff6df92.gif

Strong/Super-Strong Basin-Wide La Nina Winter (DJF) Outgoing Longwave Radiation Anomalies (Using Ensemble ONI + ONI):

1009156688_STRONG1.GIF.0324f1c1e1d59f5843854ceed6a07a18.GIF

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So from all this you can see that even with similar Nina episodes of strength and structure there can be large variations in tropical forcing. I also want to incorporate sigma velocity potential as well into this. But from here going to try and draw some conclusions regarding the tropical forcing and see if some strong correlations can be made to temperature anomalies. However, I think (and I believe Ray mentioned this several times) there likely will be a stronger correlation to [500mb] height anomalies. 

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My last post yielded an incorrect assessment. I'm sitting here looking at my printouts of ALL La Nina winter OLR Anomalies and there is the striking correlation of +OLR Anomalies within the ENSO regions which makes sense given that is a signature of La Nina events. The composites have the majority of -OLR anomalies around the Indian Ocean, however, there are some Nina events in which there were -OLR anomalies farther east.

This is probably a terrible post as there is already an answer to this, however, I am posting as I am interpreting but I am curious to see if there is a stronger consensus when breaking down via strength and structure. 

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4 minutes ago, 40/70 Benchmark said:

Try it with the ENSO region SSTs.....it defaults to 1991-2020 using NCEP/NCAR 1

Ahh I think I know why. If you're using NCEP/NCAR 1 that dataset doesn't start until January of 1948 so a climo period of 1941-1970 wouldn't work for NCEP/NCAR.

What I do is use either 20th Century Reanalysis V3 or V2c for years up through 1980. 

I then switch to NCEP/NCAR from 1981 as you can then compare to 1951-1980 climo period 

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18 minutes ago, weatherwiz said:

Ahh I think I know why. If you're using NCEP/NCAR 1 that dataset doesn't start until January of 1948 so a climo period of 1941-1970 wouldn't work for NCEP/NCAR.

What I do is use either 20th Century Reanalysis V3 or V2c for years up through 1980. 

I then switch to NCEP/NCAR from 1981 as you can then compare to 1951-1980 climo period 

I figured...I hate having to go heterogeneous with respect to databases. I was hoping I was missing something.

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29 minutes ago, 40/70 Benchmark said:

I figured...I hate having to go heterogeneous with respect to databases. I was hoping I was missing something.

Yeah it's a pain. There's also the issue too that not all variables exists within each database. For example, for OLR I had to use 20th century reanalysis V2C b/c there was no OLR data in V3.

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There is something that is baffling me. I've been doing composites for Sea-level Pressure Anomalies and exploring the SOI and moreso the Equatorial SOI. La Nina's result in +ESOI values with higher than usual pressure in the eastern Pacific and lower than usual pressure in the western Pacific. Conversely, the opposite is true during EL Nino periods. 

In order to produce some illustrations to see this visually, I took the top 5 positive/negative ESOI values for December. The left is during Nina's and the right is during Nino's. I am not seeing an opposite composite. Am I interpreting something wrong? Focusing on the wrong region (I'm focusing on equator, however, it appears there may be a bit of a correlation look closer to 30N):

nclO9xktwIAg1.tmpqq.pngncl8WoLOcUKGI.tmpqq.png

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Here is December 1983 (ESOI value -3.5 which is lowest Dec value on record). Does not seem to fit the mold which is above-average EPAC below-average WPAC

nclkcWyEnXNcM.tmpqq.png

Here is December 1999 (ESOI values 2.4 which is highest Dec value on record). This seems to fit better (above-average EPAC below-average WPAC)

nclnaeNNiJOz5.tmpqq.png

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27 minutes ago, STILL N OF PIKE said:

So what’s the latest with regard to the La Niña orientation, it’s strength , duration estimates and what it may mean for our winter 

I currently don't have any thoughts. I don't feel comfortable enough attempting a long-range forecast right now. I want to continue doing research and better understand all the variables at play and the evolution of these variables through the cool season. 

I'm sure Ray will be posting his winter weather outlook very soon and I'm really looking forward to that. Perhaps he'll share some of his initial thoughts. 

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  • 1 month later...
46 minutes ago, weatherwiz said:

@40/70 Benchmark when you do your composites and break ENSO events by strength, are you using peak strength of the event or what the strength of the event is during the DJF trimonthly period? 

Peak intensity of the event, but I tend to designate structure more by winter period..

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4 minutes ago, 40/70 Benchmark said:

Peak intensity of the event, but I tend to designate structure more by winter period..

Gotcha! That’s what I had been doing too.

I was curious if it was worth it making a subset based on strength/structure during the DJF period. Doing this would negate lag but would be curious to see if there are any differences.
 

The biggest challenges though are events which are like borderline with strength. that’s why I also want to look into other ENSO indices to help define too. 

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16 minutes ago, weatherwiz said:

Gotcha! That’s what I had been doing too.

I was curious if it was worth it making a subset based on strength/structure during the DJF period. Doing this would negate lag but would be curious to see if there are any differences.
 

The biggest challenges though are events which are like borderline with strength. that’s why I also want to look into other ENSO indices to help define too. 

I incorporate MEI into intensity ranking...

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Well I figured may as well start working on EL Nino composites. Grabbed SSTA's for all EL Nino's to try and break down into west-based, basin-wide, and east-based. I found this much more challenging then with La Nina's. The breakdown I came up with was

West-based: 5-events

Basin-wide: 25-events

East-based: 10-events

One thing I noticed was alot of variance in SSTA's across the north-central Pacific and just west off the West Coast. I don't recall such variance with La Nina, but I never saved the SSTA composites for Nina's so I have to go back and do that.

But given this I think I may try to also take a focus on SSTA's outside of the ENSO region when assessing EL Nino events

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10 hours ago, weatherwiz said:

Well I figured may as well start working on EL Nino composites. Grabbed SSTA's for all EL Nino's to try and break down into west-based, basin-wide, and east-based. I found this much more challenging then with La Nina's. The breakdown I came up with was

West-based: 5-events

Basin-wide: 25-events

East-based: 10-events

One thing I noticed was alot of variance in SSTA's across the north-central Pacific and just west off the West Coast. I don't recall such variance with La Nina, but I never saved the SSTA composites for Nina's so I have to go back and do that.

But given this I think I may try to also take a focus on SSTA's outside of the ENSO region when assessing EL Nino events

Which 5 were west based?

14-15, 09-10, 04-05, 02-03 and either 77-78 or 57-58?

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On 1/1/2023 at 1:21 AM, 40/70 Benchmark said:

Which 5 were west based?

14-15, 09-10, 04-05, 02-03 and either 77-78 or 57-58?

1929-1930

1958-1959

1968-1969

2004-2005

2014-2015

2009-2010 I did as basin wide

2002-2003 basin wide

1977-1978 basin wide

1957-1958 basin wide

I may have to definitely look more into OLR to perhaps do a better breakdown. 

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11 hours ago, weatherwiz said:

1929-1930

1958-1959

1968-1969

2004-2005

2014-2015

2009-2010 I did as basin wide

2002-2003 basin wide

1977-1978 basin wide

1957-1958 basin wide

I may have to definitely look more into OLR to perhaps do a better breakdown. 

09-10 was def west based...even though it was basin wide

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11 hours ago, 40/70 Benchmark said:

09-10 was def west based...even though it was basin wide

IDK...I think this can go either way but I certainly can see your argument for west-based. the core of the anomalies are certainly positioned towards the western edge of the ENSO region. 

May have to really go back and do another look through. This may have to be approached differently then cold anomalies.

 

nclxT62B_Ghkb.tmpqq.png

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18 minutes ago, weatherwiz said:

IDK...I think this can go either way but I certainly can see your argument for west-based. the core of the anomalies are certainly positioned towards the western edge of the ENSO region. 

May have to really go back and do another look through. This may have to be approached differently then cold anomalies.

 

nclxT62B_Ghkb.tmpqq.png

With an ENSO event that strong, they are just about always basinwide by strict definition...that is about as west biased as you will ever see at that intensity. Text book modoki. Check our of VP from that season that I posted in my last blog update..

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10 minutes ago, 40/70 Benchmark said:

With an ENSO event that strong, they are just about always basinwide by strict definition...that is about as west biased as you will ever see at that intensity. Text book modoki. Check our of VP from that season that I posted in my last blog update..

I will definitely check that out!

I'll admit...I don't really understand modoki events and what really classifies an event as modoki. I've read around a bit but find differing opinions. Something I need to look into more. I know you've highlighted them in the past so I'll go back through some of your posts.

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3 hours ago, weatherwiz said:

IDK...I think this can go either way but I certainly can see your argument for west-based. the core of the anomalies are certainly positioned towards the western edge of the ENSO region. 

May have to really go back and do another look through. This may have to be approached differently then cold anomalies.

 

nclxT62B_Ghkb.tmpqq.png

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

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