Intense spreading of radar echoes from ionospheric plasmas
Name
62621611-MIT.pdf
Description
Full printable version
Size
2.19 MB
Format
Adobe PDF
Checksum (MD5)
6d75b926583bf07dc087570e6723b2d3
Author(s)
Dorfman, Seth E
Advisor(s)
Min-Chang Lee and Richard Temkin.
Date Issued
2005
Publisher
Massachusetts Institute of Technology
Abstract
On December 25, 2004, a large-scale ionospheric plasma bubble was observed over Arecibo Observatory in Puerto Rico, inducing significant range spreading on ionograms. This phenomena may be explained by means of the E x B instability and gravitational Rayleigh-Taylor instability. A derivation of the dispersion relations for X and O mode waves transmitted from an ionosonde and an analysis of the collisional Rayleigh-Taylor instability leading to an expression for the growth rate are presented as background information. Ray tracing code developed by Nathan Dalrymple, a previous graduate student of Professor Min-Chang Lee, is extended, first to draw refractive index surfaces to illustrate a key principle in ray tracing and later to simulate range spreading due to depleted ionospheric ducts [1]. Data from Arecibo incoherent scatter radar and Arecibo's CADI digisonde is examined showing strong evidence for the development of a plasma bubble following a rise in the plasma layer and the appearance of a horizontal density gradient. In one portion of the ionosphere, this gradient is found to be at an angle of approximately 70 degrees to the Earth's magnetic field, a favorable condition for the excitation of the Rayleigh-Taylor instability over Arecibo.
Description
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.
Includes bibliographical references (leaf 41).
Subjects
Physics.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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