Researchers challenge our assumptions on the effects of planetary rotation

Coriolis Effect [credit: keywordhungry.com]

There are numerous attempts to explain the Coriolis effect on the internet, with varying success in terms of how confused the reader may be afterwards. This report may or may not clear things up, but best expect the latter.

The earth’s rotation causes the Coriolis effect, which deflects massive air and water flows toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere.

This phenomenon greatly impacts global wind patterns and ocean currents, and is only significant for large-scale and long-duration geophysical phenomena such as hurricanes.

The magnitude of the Coriolis effect, relative to the magnitude of inertial forces, is expressed by the Rossby number. For over 100 years, scientists have believed that the higher this number, the less likely Coriolis effect influences oceanic or atmospheric events, says Phys.org.

Radko and Lt. Cmdr. David Lorfeld originally focused on developing novel submarine detection systems. They approached this issue by investigating pancake vortices, or flattened, elongated mini-eddies located in the wakes of submerged vehicles. Eddies are caused by swirling water and a reverse current from waterflow turbulence.

Last year, a team led by Radko published a paper in the same AIP journal on the rotational control of pancake vortices, the first paper that challenged the famous “Rossby rule.”

In this most recent paper, the researchers showed, through numerical simulations, that internal jets of the wake can be directly controlled by rotation.

They also demonstrated that the evolution of a disorganized fine-scale eddy field is determined by planetary rotation.

Recently, researchers at the Naval Postgraduate School in California found that even smaller ocean disturbances with high Rossby numbers, like vortices within submarine wakes, are influenced by the Coriolis effect.

Their discovery challenges assumptions at the very foundation of theoretical oceanography and geophysical fluid dynamics. The team reports their findings in Physics of Fluids.

“We have discovered some major—and largely overlooked—phenomena in fundamental fluid dynamics that pertain to the way the Earth’s rotation influences various geophysical flows,” Timour Radko, an oceanography professor and author on the paper, said.

Continued here.

via Tallbloke’s Talkshop

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September 30, 2018 at 04:27AM

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