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Title: Case study of the 19 October 1989 polar-cap-absorption event using the imaging riometer for ionospheric studies. Master's thesis

Abstract

A polar cap absorption (PCA) event, beginning on 19 October 1989, is examined using the Imaging Riometer for Ionospheric Studies (IRIS) developed at the Univ. of Maryland. IRIS is a 49-beam (7 x 7) phased-array 38.2 MHz radiowave imaging system and operating at Amundsen-Scott South Pole Station, Antarctica. After applying a low-pass (>10 minute) filter, we perform a cross-correlation between the central beam and the other beams in the array. From the cross-correlation analysis, we attempt to determine whether there is any delay of effects during event onset and early main phase (plateau) within the array. For most of the period studied, no delay was detected; i.e. features of each beam's absorption time series were essentially simultaneous. However, significant delays (approx. 2 minutes) occurred at the equatorward edge during a local absorption peak occurring just prior to magnetic local noon. The peak is coincident with short-term energetic particle flux enhancements detected by GOES-7. Two possible mechanisms are proposed: a local time variation of cutoff rigidities possibly associated with the relative position of the dayside cusp, and a short-term change in energetic particle rigidity spectrum.

Authors:
Publication Date:
Research Org.:
Air Force Inst. of Tech., Wright-Patterson AFB, OH (USA)
OSTI Identifier:
6256790
Report Number(s):
AD-A-227764/8/XAB; AFIT/CI/CIA-90-076
Resource Type:
Technical Report
Resource Relation:
Other Information: Thesis
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; POLAR-CAP ABSORPTION; TIME-SERIES ANALYSIS; ANTARCTICA; CORRELATIONS; POLAR CUSP; RIOMETERS; TIME DELAY; VARIATIONS; ABSORPTION; ANTARCTIC REGIONS; MATHEMATICS; MEASURING INSTRUMENTS; POLAR REGIONS; 640201* - Atmospheric Physics- Auroral, Ionospheric, & Magetospheric Phenomena

Citation Formats

Davis, T C. Case study of the 19 October 1989 polar-cap-absorption event using the imaging riometer for ionospheric studies. Master's thesis. United States: N. p., 1990. Web.
Davis, T C. Case study of the 19 October 1989 polar-cap-absorption event using the imaging riometer for ionospheric studies. Master's thesis. United States.
Davis, T C. 1990. "Case study of the 19 October 1989 polar-cap-absorption event using the imaging riometer for ionospheric studies. Master's thesis". United States.
@article{osti_6256790,
title = {Case study of the 19 October 1989 polar-cap-absorption event using the imaging riometer for ionospheric studies. Master's thesis},
author = {Davis, T C},
abstractNote = {A polar cap absorption (PCA) event, beginning on 19 October 1989, is examined using the Imaging Riometer for Ionospheric Studies (IRIS) developed at the Univ. of Maryland. IRIS is a 49-beam (7 x 7) phased-array 38.2 MHz radiowave imaging system and operating at Amundsen-Scott South Pole Station, Antarctica. After applying a low-pass (>10 minute) filter, we perform a cross-correlation between the central beam and the other beams in the array. From the cross-correlation analysis, we attempt to determine whether there is any delay of effects during event onset and early main phase (plateau) within the array. For most of the period studied, no delay was detected; i.e. features of each beam's absorption time series were essentially simultaneous. However, significant delays (approx. 2 minutes) occurred at the equatorward edge during a local absorption peak occurring just prior to magnetic local noon. The peak is coincident with short-term energetic particle flux enhancements detected by GOES-7. Two possible mechanisms are proposed: a local time variation of cutoff rigidities possibly associated with the relative position of the dayside cusp, and a short-term change in energetic particle rigidity spectrum.},
doi = {},
url = {https://www.osti.gov/biblio/6256790}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 1990},
month = {Mon Jan 01 00:00:00 EST 1990}
}

Technical Report:
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