ENSO Updates (2007 thru 2023)

[dexterlabio]

I've seen people argue, but is there any professional grade material that indicates this was an unusual start to el nino?

BOM's ENSO outlooks prior to their declaration of El Niño this year

[cycloneye]

 https://twitter.com/BenNollWeather/status/1720805094659145750

[Kingarabian]

2 year El Ninos are very unlikely if the first year is a strong El Nino.

[weeniepatrol]

Successive WWB's to close out the year.

https://i.postimg.cc/x8QcY0rd/u-anom-30-5-S-5-N.gif

Wouldn't this help the chances of a second-year Niño?

I don't think so, multiple points to be made here:

1. Historically el Ninos of this amplitude always transition the following year

2. PDO remains negative

3. WPAC warm pool is becoming increasingly depleted. Not going to be much fuel left for any sort of El Nino next year. Need some strong trades to pile warm waters back west

[USTropics]

Successive WWB's to close out the year.

https://i.postimg.cc/x8QcY0rd/u-anom-30-5-S-5-N.gif

Wouldn't this help the chances of a second-year Niño?

I don't think so, multiple points to be made here:

1. Historically el Ninos of this amplitude always transition the following year

2. PDO remains negative

3. WPAC warm pool is becoming increasingly depleted. Not going to be much fuel left for any sort of El Nino next year. Need some strong trades to pile warm waters back west

https://i.imgur.com/jD6mxxA.gif

This

For years where ASO ONI values were 1+ and what it transitioned to next year ASO:

2015 (2.2) 2016 (-0.6)
2002 (1.0) 2003 (0.3)
1997 (2.1) 1998 (-1.1)
1987 (1.6) 1988 (-1.2)
1982 (1.6) 1983 (-0.5)
1972 (1.4) 1973 (-1.5)
1965 (1.9) 1966 (-0.1)
1963 (1.2) 1964 (-0.8)
1957 (1.3) 1958 (0.4)
1951 (1.0) 1952 (0.2)

So conclusion is, 10/10 (100%) of seasons that had ONI values of 1+ in ASO transitioned to La Nina or neutral the next year. 6/10 (60%) transitioned to La Nina the next year. ASO ONI value for this year was +1.5.

[Teban54]

One thing I'm wondering: If this El Nino is so atypical (warm Atlantic, slow atmospheric coupling, lack of WWBs until fall, etc) and in uncharted territory, how can we be sure that the typical climo of "strong El Ninos often turn into La Ninas" still applies well here? In other words, if the reduced temperature difference due to a warm Atlantic made this year more like a weak El Nino rather than a strong one, perhaps it may also not follow the traditional transition patterns of a strong Nino?

This is just one factor out of many that others have explained really well, but it's just something to think about.

[Dean_175]

Wouldn't this help the chances of a second-year Niño?

No, second year El Nino events are usually events that begin without much atmospheric coupling (like 2014) or begin late in the year like 1986 and therefore have abnormal coupling to the seasonal cycle. It will help push some more warm water east to boost the peak of this year but not likely to produce warm ENSO next year. There is decent model support for the creation of a subsurface cool pool that will spread eastward in 2024, possibly leading to La Nina, but almost certainly ending El Nino. Going by climatology, this event has been strong enough for long enough to produce negative feedback and the end of the event next year. Despite being a positive feedback coupled interaction, ENSO events are self limiting/are part of an oscillation and El Nino does not typically extend to two northern hemisphere winters. For example, while there was WWB activity in early 2016 and early 1998, both years evolved into La Nina due to changes in the distribution of Pacific equatorial ocean heat content. Since 1950, only one strong (>1.5C ONI) El Nino was followed by another El Nino (1957 was strong and 1958 was weak).

In short, a WWB now is just an indication the atmosphere is responding typically to an El Nino ocean.

But the atmosphere-ocean coupling seems to be happening only now. Many people would argue that the atmosphere for the past few months was not really El Niño-like with the lack of true WWBs in the Pacific, this in contrast to the warm Niño regions.

As you said, second year Niños seem to happen when the atmospheric response occured late in the game. This is definitely just a speculation though.

Yes, but only relatively compared to the magnitude of ocean warmth. It seems to have been enough to deplete west Pacific heat content and create a cool pool. Not something we saw in 2014. Downwelling Kelvin waves (warm pulses to the east), which we have seen this year(hence the warming to strong values) eventually lead to redistribution of Pacific heat and the dissipation of El Nino. The response becomes balanced by reduction in west Pacific ocean heat and reflection of the ENSO ocean response into upwelling Kelvin waves that bring the cool pool east to reverse the positive feedback. These upwelling waves rise the thermocline in the east and bring heat back to the west, though through the processes underlying ENSO, there is usually a reduction in total heat from the equatorial Pacific as a whole as well.

The La Nina of 98-2001 started to begin in spring 1998, when despite continued WWB and warm SSTs, there was no more great content of warm water moving eastward. The thermocline was shallow and when trade winds increased in May due to seasonal variation, they immediately upwelled cooler than usual water and led to the formation of a La Nina setup within weeks despite continued warmth of the more eastern Nino regions like 1+2. Soon enough you had stronger than usual trades over a shallow thermocline, which due to enhanced upwelling led to significant cooling in Nino3.4 , strong westward transport of the remaining heat, and a significant -ENSO for the following years. Part of the reason the year following El Nino is often globally anomalously warm is due to the discharge of heat from the equatorial Pacific that El Nino typically ends up causing.

In ahort: SST is literally just the tip of the iceberg, the depth of heat below has a lot to do with how much cooling the winds produce. If there is a cool pool spreading east, there will usually be upwelling of cooler than usual water. Sometimes, like in 98', this produces an almost immediate change in temperatures at the surface.

[USTropics]

One thing I'm wondering: If this El Nino is so atypical (warm Atlantic, slow atmospheric coupling, lack of WWBs until fall, etc) and in uncharted territory, how can we be sure that the typical climo of "strong El Ninos often turn into La Ninas" still applies well here? In other words, if the reduced temperature difference due to a warm Atlantic made this year more like a weak El Nino rather than a strong one, perhaps it may also not follow the traditional transition patterns of a strong Nino?

This is just one factor out of many that others have explained really well, but it's just something to think about.

In the grand scheme of things, ENSO is the driving force for atmosphere-ocean coupling. The Atlantic doesn't really have much say in it (i.e., Atlantic can negate some of the negative effects imposed on it by ENSO, but it's not a driving force for ENSO state). It's difficult to get multi year El ninos (after all, at its core mother nature is always trying to correct back to equilibrium). So I don't think the Atlantic SSTA would have an impact on this, it would have to be external forcings acting on ENSO state. In meteorology you learn to never say never (and we did just have a 3 year Nina essentially), but it would be highly anomalous and require extensive external forcings.

[weeniepatrol]

One thing I'm wondering: If this El Nino is so atypical (warm Atlantic, slow atmospheric coupling, lack of WWBs until fall, etc) and in uncharted territory, how can we be sure that the typical climo of "strong El Ninos often turn into La Ninas" still applies well here? In other words, if the reduced temperature difference due to a warm Atlantic made this year more like a weak El Nino rather than a strong one, perhaps it may also not follow the traditional transition patterns of a strong Nino?

This is just one factor out of many that others have explained really well, but it's just something to think about.

I get what you're saying, but I don't buy it yet. Again the WPAC is developing a cool pool, but Antimeridian westerlies are forecast to continue, which will reinforce this cool pool as yet more Pacific heat is redistributed towards the east. Nino 3.4 will peak in anomalies in a month or two due to these westerlies, but underneath the surface (literally and metaphorically) the beginnings of a transition to cold ENSO are initiating. For what little it's worth climate models love the idea of cold neutral by Summer. Of course, We still have an entire SPB coming up, and intraseasonal forcing could go either way. So, I'm not thinking it's impossible, but just quite likely that this el Nino dissipates next year. As long as the cool pool remains (and perhaps expands/strengthens following the next downwelling Kelvin wave or two that is imminent from the Dateline westerly wind burst), any inactive MJO forcing next Spring should result in upwelling Kelvin wave activity and SSTs from enhanced trades.

[cycloneye]

CPC Weekly update of 11/6/23 has Niño 3.4 up to +1.8C.

The latest weekly
SST departures are:
Niño 4=+1.4ºC
Niño 3.4= +1.8ºC
Niño 3= +2.1ºC
Niño 1+2= +2.2ºC



https://www.cpc.ncep.noaa.gov/products/ ... ts-web.pdf

[NotSparta]

One thing I'm wondering: If this El Nino is so atypical (warm Atlantic, slow atmospheric coupling, lack of WWBs until fall, etc) and in uncharted territory, how can we be sure that the typical climo of "strong El Ninos often turn into La Ninas" still applies well here? In other words, if the reduced temperature difference due to a warm Atlantic made this year more like a weak El Nino rather than a strong one, perhaps it may also not follow the traditional transition patterns of a strong Nino?

This is just one factor out of many that others have explained really well, but it's just something to think about.

I get what you're saying, but I don't buy it yet. Again the WPAC is developing a cool pool, but Antimeridian westerlies are forecast to continue, which will reinforce this cool pool as yet more Pacific heat is redistributed towards the east. Nino 3.4 will peak in anomalies in a month or two due to these westerlies, but underneath the surface (literally and metaphorically) the beginnings of a transition to cold ENSO are initiating. For what little it's worth climate models love the idea of cold neutral by Summer. Of course, We still have an entire SPB coming up, and intraseasonal forcing could go either way. So, I'm not thinking it's impossible, but just quite likely that this el Nino dissipates next year. As long as the cool pool remains (and perhaps expands/strengthens following the next downwelling Kelvin wave or two that is imminent from the Dateline westerly wind burst), any inactive MJO forcing next Spring should result in upwelling Kelvin wave activity and SSTs from enhanced trades.

Agreed, if anything this will probably be a better case of El Nino to La Nina than usual. A lot of indicators suggesting that'll happen next year

[DorkyMcDorkface]

Latest ECMWF SEAS5 plume:

[DorkyMcDorkface]

November NMME:

[zzzh]

Sep-Oct MEI dropped to 0.3
Atmosphere is lagging the SSTs by a huge amount.

[jconsor]

I agree the ENSO is the main driving force for atmosphere-ocean coupling. However, there is strong evidence that anomalous warmth in the tropical Atlantic can influence the character of the Nino (favoring a more east-based, somewhat less coupled Nino like we have been seeing, with MEI barely getting above 0.5) and can also favor a more rapid transition to La Nina. See Eric Webb's excellent post here:  https://twitter.com/webberweather/status/1720888497207480632




And his earlier post here which links to several research articles about this:  https://twitter.com/webberweather/status/1693111534216728871

One thing I'm wondering: If this El Nino is so atypical (warm Atlantic, slow atmospheric coupling, lack of WWBs until fall, etc) and in uncharted territory, how can we be sure that the typical climo of "strong El Ninos often turn into La Ninas" still applies well here? In other words, if the reduced temperature difference due to a warm Atlantic made this year more like a weak El Nino rather than a strong one, perhaps it may also not follow the traditional transition patterns of a strong Nino?

This is just one factor out of many that others have explained really well, but it's just something to think about.

In the grand scheme of things, ENSO is the driving force for atmosphere-ocean coupling. The Atlantic doesn't really have much say in it (i.e., Atlantic can negate some of the negative effects imposed on it by ENSO, but it's not a driving force for ENSO state). It's difficult to get multi year El ninos (after all, at its core mother nature is always trying to correct back to equilibrium). So I don't think the Atlantic SSTA would have an impact on this, it would have to be external forcings acting on ENSO state. In meteorology you learn to never say never (and we did just have a 3 year Nina essentially), but it would be highly anomalous and require extensive external forcings.

[jconsor]

Regarding the lack of full atmospheric coupling with the El Nino (more similar to a weak El Nino event than the water temperatures would indicate), note that the Sep-Oct MEI value dropped to 0.3 (from 0.6 in Aug-Sep): https://psl.noaa.gov/enso/mei/. Also note that the atmospheric angular momentum or AAM has been consistently neutral to negative past 90 days, indicating an atmosphere characterized by neutral to La Nina-like circulation: https://atlas.niu.edu/analysis/aam/MR-latest-90days.png

Velocity potential pattern in Oct (really since Jul) has also been very different than the typical strong Nino composite:

 https://twitter.com/tcrawf_nh/status/1722220777825824897

[cycloneye]

Here is the CPC November update. Go ahead and discuss about it.

https://www.cpc.ncep.noaa.gov/products/ ... disc.shtml

Synopsis: El Niño is anticipated to continue through the Northern Hemisphere spring (with a 62% chance during April-June 2024).

Above-average sea surface temperatures (SST) across the equatorial Pacific Ocean [Fig. 1] were indicative of a strong El Niño, with anomalies increasing in the central and east-central Pacific in the past month. The latest weekly Niño index values were +1.4°C in Niño-4, +1.8°C in Niño-3.4, +2.1°C in Niño-3, and +2.2°C in Niño-1+2 [Fig. 2]. Area-averaged subsurface temperatures anomalies increased slightly [Fig. 3] associated with the initiation of a downwelling oceanic Kelvin wave, which strengthened above-average subsurface temperatures in the central equatorial Pacific [Fig. 4]. Low-level wind anomalies were westerly in the east-central Pacific, while upper-level wind anomalies were easterly in the western and central Pacific. Convection/rainfall was enhanced around the International Date Line, extending into the eastern Pacific. Suppressed convection/rainfall strengthened around Indonesia [Fig. 5]. The equatorial Southern Oscillation Index (SOI) and the station-based SOI remained negative. Collectively, the coupled ocean-atmosphere system reflected a growing El Niño.

[Kingarabian]

We'll see over the next 3 months what effect this lack of cohesive coupling, between the ocean and atmosphere, has on the NHEM winter season.

SOI 30 day is barely in El Nino territory at -7, while the 90 day is at weak El Nino levels at -9.

[SFLcane]

Cool neutral is one of the more dangerous setups for the CONUS

[cycloneye]

Cool neutral is one of the more dangerous setups for the CONUS

And also for the Caribbean.