The South Atlantic Anomaly and its
effects on the Equatorial Ionosphere
A comparison of the TEC values across Hemispheres
Ann Kapusta
Dartmouth College
REU at MIT Haystack Observatory
August 10, 2006
Outline
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Background
Geomagnetic/Geodetic Coordinates
●
Equatorial Anomaly
●
Geomagnetic Storms
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South Atlantic Anomaly
●
●
Summer Work
Slope Comparisons
●
Maximum TEC Comparisons
●
●
Preliminary Results
Background: Geomagnetic Coordinates
Earth's Magnetic Equator
Background: Equatorial Anomaly
Background: Geomagnetic Storms
Measurement of Total
Electron Content in the
Ionosphere
Background: The South Atlantic Anomaly
The SAA as seen by ROSAT X-Ray Satellite orbiting at ~560km
Data Processing
Corrected
Geodetic (Geographic)
Geomagnetic Coordinates
Coordinates
Processed:
● 74 days worth of data
● 5 Longitude
Sectors
● 4 Times
● Geodetic and
Geomagnetic
First Approach: Slope Comparisons
Geodetic:
Geomagnetic:
First Approach: Slope Comparisons
Geodetic:
Geomagnetic:
Slope Comparison Across Seasons
Reason Our Hypothesis Was Wrong:
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Lack of Sufficient Data
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Equatorial Winds attempt to stabilize TEC
●
Storms are variable: too many mechanisms to classify
New Approach: Maximum TEC Comparisons
Quiet Days along the SAA longitude at 18:00 UT Geomagnetic Coordinates
New Approach: Maximum TEC Comparisons
Storm Days along the SAA longitude at 18:00 UT Geomagnetic Coordinates
Preliminary Results
Trends Noticed:
Period Increase and Decrease of TEC over the seasons
● Equalizing of the two hemispheres around
geomagnetic equator (difference ~ 0)
● Significant decrease in TEC in both hemispheres during
Northern Summer
● Observed greater TEC values in the longitude sectors
over and near the SAA
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A Special Thanks to:
My mentor – Anthea Coster
The Programming Guru – Bill Rideout
Larisa Goncharenko and Phil Erickson for
answering lots of questions
...and to all of you for coming!
Appendix: Programs
get_tec_cgm.m
●conv_geoCoord_to_cgmCoord.m
●plot_long_tec_values.m
●plot_madrigal_gps_conj_points.m
●graph_slopes.m
●graph_slopes_manual.m
●graph_slopes_max_tec.m
●graph_slopes_max_tec_conj.m
●plot_slopes.m
●max_tec.m
●plot_latitudes.m/plot_tec_values.m
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