C/NOFS Remote Sensing of Ionospheric Reflectance

• Published in: Journal of geophysical research. Space physics 2016-05, Vol.121 (5), p.4924-4932
• Main Authors: Burke, W. J., Pfaff, Robert F., Martinis, C. R., Gentile, L. C.
• Format: Article
• Language: English
• Subjects: Alfven waves; Alfvénic reflection coefficients; Communications systems; Conjugates; Earth orbits; Earth Resources And Remote Sensing; Energetic particles; Estimates; Field of view; Fluxes; Generators; Geophysics; incident/reflected Poynting flux; Ionosphere; Ionospherics; Magnetic fields; Magnetohydrodynamics; MSTID electrodynamics; Navigation systems; Particle precipitation; Plasmas (physics); Reflectance; Reflected waves; Reflection coefficient; Remote sensing; Satellites; Transmission lines
• ISSN: 2169-9402; 2169-9380; 2169-9402
• DOI: 10.1002/2016JA022345

Alfvn waves play critical roles in the electrodynamic coupling of plasmas at magnetically conjugate regions in near-Earth space. Associated electric (E*) and magnetic (dec B*) field perturbations sampled by sensors on satellites in low-Earth orbits are generally super positions of incident and reflected waves. However, lack of knowledge about ionospheric reflection coefficients (alpha) hinders understanding of generator outputs and load absorption of Alfvn wave energies. Here we demonstrate a new method for estimating using satellite measurements of ambient E* and dec B* then apply it to a case in which the Communication Navigation Outage Forecasting System (CNOFS) satellite flew conjugate to the field of view of a 630.0 nm all-sky imager at El Leoncito, Argentina, while medium-scale traveling ionosphere disturbances were detected in its field of view. In regions of relatively large amplitudes of E* and B*,calculated values ranged between 0.67 and 0.88. This implies that due to impedance mismatches, the generator ionosphere puts out significantly more electromagnetic energy than the load can absorb. Our analysis also uncovered caveats concerning the methods range of applicability in regions of low E* and B*. The method can be validated in future satellite-based auroral studies where energetic particle precipitation fluxes can be used to make independent estimates of alpha.