Polar reversals

The image shows a wooden top which rotates, flips upside-down, and continues to turn on its stem. Credit: Dnor.

This laboratory is an activity for you to create a method to bring about a geographic or rotational polar reversal.

Some suggested polar reversal entities to consider are rotational energy, electromagnetic radiation, neutrinos, mass, time, Euclidean space, Non-Euclidean space, and spacetime.

More importantly, there are your polar reversal entities.

You may chose to define your polar reversal entities or use those already available.

Usually, research follows someone else's ideas of how to do something. But, in this laboratory you can create these too.

## Evaluation

Main resources: Judgments/Evaluations and Evaluations

evaluation activity

Okay, this is an astronomy or geophysics polar reversal laboratory, but you may create what a polar reversal is.

Yes, this laboratory is structured.

I will provide an example of geographic, rotational polar reversal and the method proposed to bring this reversal about. The rest is up to you.

Questions, if any, are best placed on the discussion page.

## Notations

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You are free to create your own notation or use those already available.

## Hypotheses

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Main resource: Hypotheses

1. Geographic polar reversals could be induced by a passing object of sufficient size.
2. A surface impact could induce a true polar wander (TPW) including approximate polar reversal.

## Control groups

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For creating a polar reversal, what would make an acceptable control group? Think about a control group to compare your polar reversal technique or your process of creating a polar reversal to.

For this laboratory, my control group is the crustal mass distribution above the lithosphere on present day Earth.

## Sampling

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Main resources: Models/Sampling and Sampling

Here are four resources that address geographic polar wandering or reversal:

1. Secular "rotational stability [may be] in response to loading using the fluid limit of viscoelastic Love number theory. [...] an uncompensated surface mass load [...] of any size would drive true [rotational] polar wander (TPW) that ultimately reorients the load to the equator."[1] The "equilibrium pole position is a function of the lithospheric strength, [with] significantly larger predicted TPW for planets with thin lithospheres. [...] nonaxisymmetric surface mass loads and internal (convective) heterogeneity, even when these are small relative to axisymmetric contributions, can profoundly influence the rotational stability. Indeed, [...] nonaxisymmetric forcing initiates an inertial interchange TPW event (i.e., a 90° pole shift)."[1] A two-step process, depending on the mass loading could place the rotational pole from one end, to the equator, then to the other end.
2. "Stratospheric sudden warmings (SSWs) are extreme events in the polar stratosphere that are both caused by and have effects on the tropospheric flow. This means that SSWs are associated with changes in the angular momentum of the atmosphere, both before and after their onset. Because these angular momentum changes are transferred to the solid Earth, they can be observed in the rate of the Earth's rotation and the wobble of its rotational pole."[2] An "anomaly in the orientation of the Earth's rotational pole, up to 4 times as large as the annual polar wobble, typically precedes SSWs by 20-40 days. The polar motion signal is due to pressure anomalies that are typically seen before SSW events and represents a new type of observable that may aid in the prediction of SSWs. A decline in the length of day is also seen, on average, near the time of the SSW wind reversal and is found to be due to anomalous easterly winds generated in the tropical troposphere around this time, though the structure and timing of this signal seems to vary widely from event to event."[2]
3. There are "two new finite rotation poles from visual-fitting, for chron C33 in the Bellingshausen Sea sector."[3]
4. "The pattern of focal mechanisms and plate motion studies suggest that [the CAPricorn and AUStralian diffuse plate boundary] is made of two disjoint zones, on either side of the CAP/AUS rotation pole."[4]

## Teatment group

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The "equilibrium pole position is a function of the lithospheric strength, with a convergence to Willemann's results evident at high values of elastic thickness [...], and significantly larger predicted TPW for planets with thin lithospheres. [...] [N]onaxisymmetric surface mass loads and internal (convective) heterogeneity, even when these are small relative to axisymmetric contributions, can profoundly influence the rotational stability. [There are] relatively permissive conditions under which nonaxisymmetric forcing initiates an inertial interchange TPW event (i.e., a 90° pole shift)."[1]

## Verifications

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Main resources: Assessments/Verifications and Verifications

## Writings

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Main resources: Communications/Writings and Writings

Polar reversal due to an elastic lithosphere

by --Marshallsumter (discuss • contribs) 20:53, 24 May 2018 (UTC)

Abstract

Introduction

Experiment

Results

Discussion

Conclusion

## Evaluations

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Main resources: Judgments/Evaluations and Evaluations

To assess your polar reversal mechanism, including your justification, analysis and discussion, I will provide such an assessment of my example for comparison and consideration.

Evaluation

## See also

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* Magnetic field reversal

## References

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1. ↑ 1.0 1.1 1.2 I. Matsuyama, J. X. Mitrovica, M. Manga, J. T. Perron and M. A. Richards (February 2006). "Rotational stability of dynamic planets with elastic lithospheres". Journal of Geophysical Research Planets 111 (E2): 1991-2012. doi:10.1029/2005JE002447. http://onlinelibrary.wiley.com/doi/10.1029/2005JE002447/full. Retrieved 2014-07-15.
2. ↑ 2.0 2.1 Lisa Neef, Sophia Walther, Katja Matthes, and Kunihiko Kodera (August 2014). "Observations of stratospheric sudden warmings in Earth rotation variations". Journal of Geophysical Research: Atmospheres 119 (16): 9666-78. doi:10.1002/2014JD021621. http://adsabs.harvard.edu/abs/2014JGRD..119.9666N. Retrieved 2015-06-18.
3. ↑ G. Eagles, K. Gohl, and R. Larter (6-11 April 2003). "Animated reconstruction of gravity anomalies in the Bellingshausen and Amundsen Seas". EGS - AGU - EUG Joint Assembly, Abstracts: #1369. http://adsabs.harvard.edu/abs/2003EAEJA.....1369E. Retrieved 2015-06-18.
4. ↑ J. Royer, C. Deplus, J. Goslin, P. Patriat, and C.Widiwijayanyi (December 2001). "Intraplate Deformation in the Central and Eastern Indian Ocean: Results from a Swath-Bathymetry Survey (MD118-Deflo Cruise)". American Geophysical Union, Abstracts: #T11A-0844. http://adsabs.harvard.edu/abs/2001AGUFM.T11A0844R. Retrieved 2015-06-18.

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