Solar variability weakens the Walker cell

Posted: March 30, 2019 by oldbrew in atmosphere, climate, Cycles, Natural Variation, Ocean dynamics, research, wind
Tags: , ,

Credit: PAR @ Wikipedia


This looks significant, pointing directly at solar influences on climate patterns. The researchers found evidence that atmosphere-ocean coupling can amplify the solar signal, having detected that wind anomalies could not be explained by radiative considerations alone.

An international team of researchers from United Kingdom, Denmark, and Germany has found robust evidence for signatures of the 11-year sunspot cycle in the tropical Pacific, reports Phys.org.

They analyzed historical time series of pressure, surface winds and precipitation with specific focus on the Walker Circulation—a vast system of atmospheric flow in the tropical Pacific region that affects patterns of tropical rainfall.

They have revealed that during periods of increased solar irradiance, the trade winds weaken and the Walker circulation shifts eastward.

Stergios Misios, a postdoctoral researcher at the University of Oxford, said, “We deal with a very short record of observations in the tropical Pacific, and we must be very careful with how we filter out other interannual fluctuations. After a careful treatment of the data covering the last 60 years, we detected a robust slowdown of the Walker cell during years associated with solar-cycle maxima.”

The analysis shows that in tandem with changes in the wind anomalies, the dominant patterns of tropical precipitation shift to the central Pacific during solar-cycle maxima. As a result, rainfall decreases over Indonesia and in the western Pacific, and increases over the central Pacific Ocean.

Simple mechanisms amplify the solar signal

The issue of solar influences on climate is long and controversial, as there have been numerous claims that did not survive proper statistical scrutiny in most cases.

But besides statistical verification lies an even more challenging problem: How could miniscule changes in incoming solar radiation produce significant climate signatures?

“Soon enough, we realized that the magnitude of the wind anomalies that we detected in observations simply could not be explained by radiative considerations alone. We thought that if it comes from the sun, there must be another mechanism that amplifies the weakening of the Walker circulation,” said Prof. Lesley Gray of University of Oxford.

With the aid of a global climate model, this mechanism was found in the dynamical coupling between the atmosphere and ocean circulation in the tropical Pacific.

Continued here.

Comments
  1. craigm350 says:

    Reblogged this on WeatherAction News and commented:
    Hopefully the start of some more investigations by scientists, rather than the IPCC’s rather lame view of solar climate influence.

  2. ren says:

    The circulation block starts above the polar wheel in the stratosphere and is associated with an increase in ionizing radiation (secondary GCR radiation) in the lower stratosphere during periods of low solar activity.

  3. ren says:

    The increase in ionizing radiation is in line with the geomagnetic cutoff force.

  4. ren says:

    The impact of blocking circulation over the equatorial Pacific Ocean is visible in Niño 3.4 1+2 region.

  5. ren says:

    Sorry, Niño 1.2 region.

  6. oldbrew says:

    ren says: March 30, 2019 at 12:39 pm

    Interesting stuff.

  7. erl happ says:

    Ultimately, the driver is the very large changes in surface pressure relations between the margins of Antarctica and the rest of the globe. The atmosphere above the high latitude southern ocean is the ever present global surface pressure sink….but variable in its intensity on all time scales. Ren points to the influence of galactic cosmic rays and the state of ionization of the atmosphere in high southern latitudes. The atmosphere rotates in the same west to east direction as the planet, but faster than the planet, variably faster. The length of day changes accordingly and in concert with the length of day we see change in the planetary winds. Electromagnetic forces are at play.

    What’s happening in the tropical Pacific is at best a residual, but of course highly influential in determining surface temperature because it influences the spread of the warmer surface waters towards the east from their usual habitat close to south east Asia where tropical convection and precipitation is most intense.When the warm waters spread eastwards, as the trade winds fall away, Indonesia experiences a relative drought.

    Wind is driven by surface pressure relations. The most active region in terms of change in surface pressure relations is from 50-70° south latitude.

  8. ren says:

    Erl Happ
    In the southern hemisphere has already created the winter stratospheric polar vortex.
    https://earth.nullschool.net/#2019/03/30/1800Z/wind/isobaric/10hPa/orthographic=-13.21,-87.47,296

  9. Crosspatch says:

    This seems interesting because it would imply that El Nino conditions would be less likely to occur during periods of extreme solar minima. I recall reading a paper that said during the LIA there appeared to be a pattern of persistent La Nina conditions in the equatorial Pacific. Putting that fact together with the fact that the LIA was a period of long term solar quiescence, we might now have some longer term evidence that this does actually happen.

  10. stpaulchuck says:

    why do you people keep trying to ‘prove’ that the sun is the major driver of our global temperature both directly and indirectly??

    Everyone knows it’s cow farts and backyard grills. The CO2 is all. All hail the CO2 and it’s prophet the Goreacle!

  11. oldbrew says:

    Climate models may need an update…

    “Soon enough, we realized that the magnitude of the wind anomalies that we detected in observations simply could not be explained by radiative considerations alone. We thought that if it comes from the sun, there must be another mechanism that amplifies the weakening of the Walker circulation,” said Prof. Lesley Gray of University of Oxford.

    With the aid of a global climate model, this mechanism was found in the dynamical coupling between the atmosphere and ocean circulation in the tropical Pacific. [bold added]
    – – –
    If radiative factors alone don’t cut it – no CO2 ‘control knob’. But we knew that anyway 😎

  12. Phoenix44 says:

    If climate is chaotic and non-linear then small changes can cause big changes.

  13. oldbrew says:

    APRIL 2, 2019
    Natural climate processes overshadow recent human-induced Walker circulation trends
    by Institute for Basic Science

    A new study, published this week in the journal Nature Climate Change, shows that the recent intensification of the equatorial Pacific wind system, known as Walker Circulation, is unrelated to human influences and can be explained by natural processes. This result ends a longstanding debate on the drivers of an unprecedented atmospheric trend, which contributed to a three-fold acceleration of sea level rise in the western tropical Pacific, as well as to the global warming hiatus. [bold added]

    https://phys.org/news/2019-04-natural-climate-overshadow-human-induced-walker.html
    – – –
    ‘recent human-induced Walker circulation trends’ – the ones we made up earlier?
    ‘global warming hiatus’ – the one some alarmists pretend doesn’t/didn’t exist?

    Quote: In contrast to the observed strengthening, the majority of climate computer models simulate a gradual weakening of the Walker Circulation when forced by increasing greenhouse gas concentrations (see Figure 1). “The discrepancy between climate model projections and observed trends has led to speculations about the fidelity of the current generation of climate models and their representation of tropical climate processes,” said Eui-Seok Chung, researcher from the Center for Climate Physics, Institute for Basic Science, South Korea, and lead author of the study. [bold added]

    Fidelity issues of climate models? Oh dear 😁

    Quote: Given the high levels of natural decadal variability in the tropical Pacific, it would take at least two more decades to detect unequivocally the human imprint on the Pacific Walker Circulation (see Figure 1, right panel).

    That’s a side-splitter 🤣

  14. Here is evidence that confirms that there is a weakening (or slow down) of the Walker Circulation at times near solar maximum.

    https://astroclimateconnection.blogspot.com/2019/04/evidence-that-11-year-solar-cycle.html

    My evidence is in agreement with a recently published paper:

    Slow Down of the Walker circulation at solar cycle maximum
    Stergios Misios, Lesley J. Gray, Mads F. Knudsen, Christoffer Karoff, Hauke Schmidt, & J. D. Haigh
    PNAS published ahead of print March 29, 2019 https://doi.org/10.1073/pnas.1815060116

    The authors of this paper provide robust evidence that the solar (sunspot) cycle affects decadal variability in the tropical Pacific. Using the analysis of independent observations, they demonstrate a slowdown of the Pacific Walker Circulation (PWC) at solar cycle maximum.

  15. oldbrew says:

    From the PNAS paper:

    Given that the radiative imbalance at the top of the atmosphere barely exceeds 0.18 W/m2 between Smin and Smax, radiative forcing alone suggests a very modest global mean surface warming of only 0.08–0.16 K

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s