Physics
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufmsa51d1978c&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #SA51D-1978
Physics
[2409] Ionosphere / Current Systems
Scientific paper
Motivated by an almost vertical geomagnetic field and associated simplicity of ionospheric current system over Resolute Bay, Canada, we embarked on a comparative radar-magnetometer data analysis to measure the ionospheric Pedersen current, however, our analysis is yielding a surprising result that an external current system is significantly biasing magnetometer measurements away from the direction that was supposed to be dominated by overhead Hall and Pedersen currents in the ionospheric E region. Magnetometers at Resolute Bay, Thule and Cambridge Bay observatories (part of CANMOS) and the new Resolute Bay incoherent scatter radar (ISR) data are the primary measurements used in this study. Magnetometers measure the magnetic deflection from the summation of both Pedersen and Hall currents contributed by ions and electrons. ISRs can be used to calculate a magnetic deflection contributed from the Hall and Pedersen current of the ions. Our analysis of the discrepancy between the two deflection angles suggests the effect of an external (field-aligned or magnetospheric) current. More precisely, in a particular coordinate system we used, we expected that the radar calculated magnetic deflection angle on the ground (assuming an electrojet current) would be leading the magnetometer deflection angle. Analysis of the deflection angles between magnetometer and radar showed a noticeable phase delay between the two. The magnetometer deflection angle was ahead (expected to precisely match for Hall currents only and behind if Pedersen currents are also included)in phase by 2-3 hours compared to the radar deflection angle as seen in Figure 1. Inclusion of the neutral winds reduced the offset angle, nevertheless it was not sufficient enough to explain the discrepancy. Furthermore an application of current inversion using the three magnetometer stations aforementioned slightly decreased the discrepancy. However, after both methods were implemented a significant (~2h) offset still remained. Currently we are investigating sources (magnetospheric currents, neutral winds) that could be a cause for such a large offset between the magnetometer deflection angle and radar deflection angle.
Bahcivan Hasan
Chen Shouxin
Cosgrove Russell B.
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