Plasma Physics Colloquium
Friday,
December 2, 2016
2:00 PM - 3:00 PM
Dr. Caitano L. da Silva
Department of Physics and Astronomy, Dartmouth College
"Coupling of Atmospheric Regions by Transient Plasmas"
The ledge in electron density in the lower ionosphere (at 80 km altitude during nighttime) marks the interface between (neutral) atmosphere and space. It is also the sharp boundary of the global VLF waveguide. The mesosphere-lower ionosphere region is subject to energy input from above and below, evidencing the coupling between atmosphere and space. This talk addresses the transient plasma phenomena that signals this coupling.
Department of Physics and Astronomy, Dartmouth College
"Coupling of Atmospheric Regions by Transient Plasmas"
The ledge in electron density in the lower ionosphere (at 80 km altitude during nighttime) marks the interface between (neutral) atmosphere and space. It is also the sharp boundary of the global VLF waveguide. The mesosphere-lower ionosphere region is subject to energy input from above and below, evidencing the coupling between atmosphere and space. This talk addresses the transient plasma phenomena that signals this coupling.
Upward Coupling: Electric fields created by lighting and thunderstorms generate transient plasma byproducts in the middle and upper atmosphere. Examples are sprites, halos, elves, gigantic jets, collectively known as transient luminous events (TLEs). Gigantic jets, for instance, are upward lightning that escape cloud tops and discharge thunderstorms to the ionosphere. Downward Coupling: Plasma electromagnetic waves in the whistler mode, known as chorus, can efficiently interact with energetic electrons trapped in the Earth’s radiation belts and dump them into the neutral atmosphere. A direct optical evidence of chorus-driven energetic electron precipitation (EEP) is the so-called pulsating aurora. This talk will address the physics of lightning, TLEs, chorus, and EEP, and how these processes intermediate the coupling between atmosphere and space.
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