Date of Award


Document Type


Degree Name

Master of Science in Applied Physics


Department of Engineering Physics

First Advisor

Daniel Emmons, PhD


A global, multi-year comparison of low and mid-latitude COSMIC GPS radio occultation (RO) sporadic-E (Es) plasma frequency and altitude and Digisonde blanketing frequency (fbEs) and altitude within 150 km and 30 minutes of each other. RO methods used to estimate the intensity of the Es layer include the scintillation index S4, total electron content (TEC) with both a constant and variable Es cloud thickness, and an Abel transform. The S4 and TEC with varying thickness techniques both under-represent the fbEs values while the TEC with constant thickness and Abel transform better estimate Digisonde fbEs values. All RO methods underestimate the altitude of the fbEs events as measured by the Digisondes. No method outperformed the other techniques across every metric, but the physical basis of the TEC technique provides an advantage over the empirically derived S4. The Abel transform also shows promise, but the lower resolution data currently available is detrimental to its performance. Overall, an automated TEC method tested on a larger data set could prove valuable for real-time global Es observation.

AFIT Designator


DTIC Accession Number