Thursday, August 20, 2015

Mid-August ENSO report - El Niño still strengthening

Sou | 1:46 AM Go to the first of 11 comments. Add a comment

The 2015 El Niño has continued to strengthen over the past fortnight. The ocean and atmosphere are reinforcing each other, with tropical Pacific Ocean temperatures well above El Niño thresholds, consistently weakened trade winds, and a strongly negative Southern Oscillation Index. Strong coupling of the tropical Pacific Ocean and atmosphere is typical of a mature El Niño, and suggests only a small chance of the event finishing before the end of the year.

All international climate models surveyed by the Bureau of Meteorology indicate the tropical Pacific is likely to warm further, peaking later in the year. Typically, El Niño peaks during the late austral spring or early summer, and weakens during late summer to autumn.


The model outlook from BoM shows the likely strengthening of El Nino over September, then a leveling out of sea surface temperature anomalies before falling back early next year:

Next an animation of sub-surface temperatures in the equatorial Pacific, down to 400m, starting in January 2014 through to August 2015. This year is different to last year. These are from BoM.

Here's an animation of sea surface temperatures across the Pacific, from NOAA images from January this year through to 17 August:

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  1. I follow several other climate weather blogs, and there are many many ENSO models out there that show varying strenth and duration for this event (No disrespect meant to the BOM). There are also many indexes by which ENSO is measured, its just the Nino 3.4 region gets the most press.
    CFSv2: (raw output, most fun to look at)

    (PDF Corrected, ie probably more reality based)

    European Model:

    Progression of the Euro model's forecast:

    Multi Model Ensemble:

    BOM publication about the local effects of El Nino:

    "Monster El Nino":

    1. It's hard to see the momentum slowing in the next couple of months.

      To put things into context, last summer the Monterey Bay weather buoy set its all-time record of 65F/18C. El Niño didn't quite happen due to the trade wind shift not coming about, as I understand it. But plenty of warm water sloshed over here.

      As of about a week ago, the Monterey Bay weather buoy set a new record of 69F/21C and of course the El Niño pattern is in place, as BOM says, and mostly expected to continue growing.

      Now the weather buoy's not been around that long (but long enough to show that we're killing 1998 locally). And El Niño is based on anomalous, not absolute, conditions including winds not just temps. In terms of anomaly against the rolling and rising average used by the ENSO folks, aparently wer're about where we were in 1998.

      An our weather buoy is just one data point. But temps are running rampant up and down the eastern pacific, not just here.

      We're all very curious as to what's going to happen in the bay, one of the most productive marine areas in the world. Warm temps supposedly favor sardines over anchovies, due to some PDO cycle based correlations, but the sardine season's been closed since April 15 (should've been closed last year) and anchovies are going nuts leading to displays of lunge-feeding humpbacks that are pretty much off the charts by any standard south of the Alaska bubble-netting/herring-feeding cooperative groups. On the other hand our blue whales are staying offshore. Common dolphins, relatively rarely seen here, have been in the bay in numbers up to 2000 since April 2014.

      So this El Niño is already bringing big changes (actually the pre-El Niño conditions last year began them) locally and the research community here (there are four research facilities on the bay proper) is waiting to see what comes next. Conditions are unprecedented in absolute temperature terms ...

    2. To put things in context, the high temp mark mentioned above is perhaps 15F/8C above normal for this time of year - of course, there's a lot of variation possible due to lack of wind leading to stratification and the like, but still, it's amazing people.

    3. 65 out at the Monterey Bay Buoy? That's fucking' hot. It is way the hell out there on a line drawn across the mouth of the bay and about halfway between Davenport and Pacific Grove. Friends of mine who still live in Santa Cruz have remarked on how silly warm the water is.

    4. 65F was last year. 69F busted it about 10 days ago. And in early july when we were several miles offshore of Carmel and south to Point Sur temps were in the low 60s. Temps in the bay actually cooled during May/June due to some upwelling dragging cold water up from the canyon but that didn't last, as the buoy temps demonstrate!

      And, yes, the buoy you describe is the one. Out where the albatrosses play :)

    5. Been out there many times over the years.

  2. Too bad the bloggers at ATTP won't allow me to comment with a reference to this breakthrough paper on ENSO

    H. Astudillo, R. Abarca-del-Rio, and F. Borotto, “Long-term non-linear predictability of ENSO events over the 20th century,” arXiv preprint arXiv:1506.04066, 2015.

    They seem to think discussion of ENSO and El Nino is "drive-by" commentary.

    1. That's probably reasonable if it's OT. Also, ENSO events affect countries around the Pacific, not so much the Atlantic (where ATTP is located). We could be in for a warm summer this year where we live.

    2. Given that you repeat very similar ENSO comments below posts about any topic I can imagine and must admit that I have started skipping your comments. I am sure that next time ATTP has a post on ENSO you would be welcome to explain that pre-print. (Friendly intended feedback.)

      Yes, I also live far from the Pacific. :-)

    3. At the moment WHT is only about 0.2 on the scale I just made up called the JOnathan vos Post scale. It is named after someone who, every post they made on people's blogs/ forums, was directly related to them and how wonderful they were. I appreciate that WHT is clearly more level headed and not as big headed, but the repeated comments about El Nino prediction etc were often off topic and snide.

  3. Part of this is to drum up support for the Azimuth Project on El Nino prediction. The leader of the project is sensing lagging participation, and all I am doing is trying to generate some enthusiasm.

    Remember that ENSO is the major driver of global climate variability, and if you think that because someone lives on the Atlantic that they are not impacted, then you may be misguided.



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