New mechanism for El Nino enhanced storm systems

From the INSTITUTE OF ATMOSPHERIC PHYSICS, CHINESE ACADEMY OF SCIENCES

New mechanism to explain how El Niño influences East Asian and WN Pacific climate

Western North Pacific anomalous anticyclone (WNPAC, or referred to as Philippine Sea anomalous anticyclone) is the most important anomalous circulation pattern connecting El Niño and East Asian-western North Pacific monsoon.

WNPAC begins from the El Niño mature winter to the following summer and thus is one of the most long-lasting anomalous circulation patterns over the entire tropical climate system.

Researchers from the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences and University of Hawaii proposed a new mechanism to explain the maintenance of WNPAC. The mechanism was named as “anomalous moist enthalpy advection mechanism”. The research team applied this mechanism to explain why WNPAC forms in the late fall of El Niño developing phase.

Schematic of the anomalous moist enthalpy advection mechanism. Warm SSTAs in the equatorial CEP (red line) enhance local convection (green shading) and thus stimulate cyclonic anomalies to the northwest (black solid line). The northerly component of the western flank of the cyclonic anomalies advects off-equatorial dry (low moist enthalpy) air into the tropical WNP and thus suppresses convection there (orange shading). The suppressed convection further stimulates the WNPAC (black dashed line) to the northwest. CREDIT (Wu et al. 2017a)

Since the 2000s, it has been widely accepted that WNPAC is maintained by local air-sea interaction via wind-evaporation-Sea Surface Temperature (SST) feedback over the tropical WNP during El Niño mature winter and the following spring.

However, some recent studies found that WNPAC can be simulated by an Atmospheric General Circulation Model (AGCM), driven by El Niño-related warm SST anomalies in the central-eastern Pacific plus climatological SST in other ocean areas.

This indicated that WNPAC can be maintained by an atmospheric bridge from equatorial central-eastern Pacific without the help of local air-sea interactions in the WNP.

The contradiction between the leading theory and the AGCM experiments suggests that a new theory is needed to be developed for the maintenance of WNPAC.

“The ‘anomalous moist enthalpy advection mechanism’ proposed in our study works through pure atmospheric dynamic and thermodynamic processes and does not rely on the local air-sea interactions in the WNP,” says Dr. WU Bo, lead author of the study published in Journal of Climate.

According to the study, idealized numerical experiments further suggested that the contribution of the new mechanism to WNPAC is larger than that of the local air-sea interactions.

“Furthermore, the new mechanism can reasonably explain the formation timing of WNPAC, which cannot be explained by previous theories,” says Prof. ZHOU Tianjun from IAP, a co-author of the study.

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Wu, B., T. Zhou, T. Li, 2017a: Atmospheric dynamic and thermodynamic processes driving the western North Pacific anomalous anticyclone during El Niño. Part I: Maintenance mechanisms, Journal of Climate, 30, 9621-9635. http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0489.1

Wu, B., T. Zhou, T. Li, 2017b: Atmospheric dynamic and thermodynamic processes driving the western North Pacific anomalous anticyclone during El Niño. Part II: Formation processes, Journal of Climate, 30, 9637-9650. http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0495.1

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23 thoughts on “New mechanism for El Nino enhanced storm systems

  1. Take out the first word ‘anomalous’. If this is the natural mechanism it’s not anomalous. They draft up obfuscatory nomenclature like social sciences do to look sciency. Uh guys, you are scientists, or have I got that wrong. wrong?

    • Same with calling this discovered process a new mechanism. Of course, it’s not been proven by observation yet.

    • Gary Pearse. December 12, 2017 at 9:16 am
      Take out the first word ‘anomalous’. If this is the natural mechanism it’s not anomalous. They draft up obfuscatory nomenclature like social sciences do to look sciency. Uh guys, you are scientists, or have I got that wrong. wrong?

      You have got it wrong Gary.
      It is an anomaly: deviation from the normal or common.
      ..from the usual, from the average, from what you’d expect to see…an anomaly.

      There is no “they” and there is no “obfuscatory nomenclature”. Just an interesting, temporary anomaly. Especially the “atmospheric bridge” aspect. It demontrates what a complex, difficult to predict system the atmosphere is. You are reading way, way too much into it.

      [Please clarify what you are quoting, and what you are saying over your own user_id. If only the first paragraph, as we suspect, please use blockquotes. .mod]

      • Gary Pearse said:
        “Take out the first word ‘anomalous’. If this is the natural mechanism it’s not anomalous. They draft up obfuscatory nomenclature like social sciences do to look sciency. Uh guys, you are scientists, or have I got that wrong. wrong?”

        Then I said:
        “You have got it wrong Gary…”

    • Excerpted from published commentary:

      New mechanism to explain how El Niño influences East Asian and WN Pacific climate

      Western North Pacific anomalous anticyclone (WNPAC, or referred to as Philippine Sea anomalous anticyclone) is the most important anomalous circulation pattern connecting El Niño and East Asian-western North Pacific monsoon.

      @ Gary Pearse & Tony Mcleod

      Iffen you are going to get “picky” with the verbiage as stated by the author ……. then you should have criticized the 1st sentence.

      “DUH”, it is not a “new mechanism” that was discovered, …… but was a “newly discovered mechanism” that has been affecting the “circulation pattern connecting El Niño and East Asian-western North Pacific monsoon(s)”. ……. most probably for the past tens-of-thousands of years.

      Anyway …………..

      So stated: Gary Pearse

      Take out the first word ‘anomalous’. If this is the natural mechanism it’s not anomalous.

      So criticized: Tony Mcleod

      You have got it wrong Gary.
      It is an anomaly: deviation from the normal or common.

      And Sam C says:
      “DUH”, …… IMLO, ….. it is not an “anomaly” if, …… given El Niño/monsoon conditions, ……. it has been a naturally occurring mechanism for the past tens-of-thousands of years.

      “HA”, …… fer shur the first few Solar eclipses that were observed by curious hominoids were declared to be “anomalies”, …… that is until they got “astrology” smart.

      And don’t be fergettin about the most famous “anomaly” ever, …. which also wasn’t one.

      It t’was the “extra bright Star” in the sky over Bethlehem that the “three wise men riding camels” were “tracking” across the desert sands in hopes of catching up with.

      Supernovas occur all the time ….. and noinfrequently are observed by humans, …… but that limited sightings doesn’t prove said are “anomalous” events.

  2. Looks to me like they’ve resorted to simulating epicycles on top of epicycles.

    But on a positive note, at least they didn’t invoke the mystical properties of the MagicMolecule™.

    • While the solar system doesn’t, the climate system might well actually have epicycles.

      It’s that unsettled.

      • Joel,

        If a believer in classical paganism, then the good astronomer Ptolemy could look forward either to a normal life in the Underworld on the Plains of Asphodel, had he been a good citizen, or to Tartarus, ie Hell, which was not droll, but also not eternal punishment. His sentence would have depended upon how bad he had been above ground. He was not eligible for the Elysian Fields, ie paradise, not having been a valiant warrior.

      • Gabro,

        “… ie Hell, which was not droll, but also not eternal punishment.”

        Temporary then? What happens after that?

      • John,

        In classical pagan religion, after you served your sentence in Tartarus, you got promoted to the Fields of Asphodel.

        Christianity picked up its conception of Hell from pagans, rather than the Bible, but made it more dire.

      • Sorry. Meant Plains, not Fields.

        Elysian Fields were the Greco-Roman equivalent of Valhalla in Norse mythology or religion, reserved for warriors, preferably dying in battle with weapon in hand.

    • Well you can run experiments on computer models. But all you will ever find out is what has been programmed into the computer model. It would be easier to ask the programmer what they have programmed in but where’s the fun in that?

      • I’ve only seen thought experiments employed as a means to help people understand a hypothesis or theory, never to test one.

        SR

      • Einstein was famous for thought experiments as a way of visualizing his theories. He never considered them a substitute for experiment. As he said in a reply to the Nazi scientists who denounced his theories, “Why does it take 100 signatures when a single experiment would be enough.”

  3. What’s anomalous about this “new” mechanism is that it was recognized by Klaus Wyrtki decades ago, before the Chinese study.

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