Date of Award

3-11-2011

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Engineering Physics

First Advisor

Ariel O. Acebal, PhD.

Abstract

A sensitivity analysis of empirical parameters used in physics-based models was completed in this study to determine their effect on electron densities and total electron content (TEC) in the ionosphere. The model used was the Ionosphere-Plasmasphere Model (IPM) developed by Utah State University. The empirical parameters studied include the O+/O collision frequency, zonal wind, secondary electron production, nighttime ExB drifts, and tidal structure. The sensitivity analysis was completed by comparing a default run of the IPM to a run with the parameter adjusted for three geophysical cases. Many of the comparisons resulted in nonlinear changes to the model output. Doubling the O+/O collision frequency increased NmF2 up to 250% in the equatorial anomalies. Setting the zonal winds to zero resulted in a 400% increase in TEC units (TECU) over the Southeast Pacific and a 50% decrease near Madagascar. It was found that changes in electron density and TEC are directly proportional to how daytime production is scaled to account for secondary electron production. Decreasing the nighttime downward ExB drift resulted in a 160%-630% increase in low latitude TEC. Finally, modulating the ExB drift to simulate tidal forcing reproduced the four-wave pattern of enhanced low latitude TEC.

AFIT Designator

AFIT-GAP-ENP-11-M03

DTIC Accession Number

ADA538259

Download

Share

COinS