Browsing by Author "Hedden, R. B."

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    Comparing F region ionospheric irregularity observations from C/NOFS and Jicamarca
    (American Geophysical Union, 2009-07-11) Hysell, D. L.; Hedden, R. B.; Chau Chong Shing, Jorge Luis; Galindo, F. R.; Roddy, P. A.; Pfaff, R. F.
    Observations of plasma density irregularities associated with equatorial spread F (ESF) have been made using the Jicamarca Radio Observatory and the Plasma Langmuir Probe (PLP) and Vector Electric Field Instrument (VEFI) instruments on the Communications Navigation Outage Forecast System (C/NOFS) satellite during a close spatio-temporal conjunction. The radar data resolution is of the order of 1 km and a few sec. in space and time, respectively. We find that coherent scatter intensifications at these scales are coincident and collocated with plasma density depletions as determined by C/NOFS. The Doppler shifts of the localized echoes are also comparable to the vertical components of the E × B plasma drifts. The strongest backscatter does not necessarily come from the deepest or most rapidly convecting depletions. This implies a complex relationship between coherent backscatter and the underlying state parameters in the ionospheric plasma.
    Palabras clave:Spread FIrregularitiesCoherent scatter
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    Comparing Jicamarca and C/NOFS (PLP, VEFI): observations of equatorial spread F irregularities
    (Instituto Geofísico del Perú, 2009) Hysell, D. L.; Hedden, R. B.; Chau Chong Shing, Jorge Luis; Galindo, F. R.; Roddy, P. A.; Pfaff, R. F.
    Diapositivas presentadas en The Meeting of the Americas, 2009 Joint Assembly, organizadas por la American Geophysical Union del 24 al 27 mayo de 2009 en Ontario, Canada.
    Palabras clave:Geophysical observatoriesRadarAtmospheric dispersion
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    Magnetic aspect sensitivity of 3‐m F‐region field‐aligned plasma density irregularities over Jicamarca
    (American Geophysical Union, 2011-10) Hysell, D. L.; Hedden, R. B.; Swartz, W. E.; Farley, D. T.; Chau Chong Shing, Jorge Luis; Milla, Marco
    The magnetic aspect angle sensitivity of 3‐m plasma density irregularities in the F‐region ionosphere over Jicamarca has been measured during the passage of a radar plume in an equatorial spread‐F event. The measurement technique utilizes radar interferometry with a number of antenna baselines with different lengths and orientations. Several corrections are applied to the data to reduce experimental biases. The RMS aspect angle half widths (the square root of the angular variance, the standard deviation) were found to be 0.01 ± 0.005° in a bottomside layer and near the top of the plume and 0.02 ± 0.005° in the central channel of the plume near F‐peak altitudes. In the frequency domain, the magnetic aspect width was narrowest at small Doppler shifts and broader in the wings of the spectra when wings existed. These findings appear to be reasonably consistent with theoretical predictions, although questions remain.
    Palabras clave:IonosphereIrregularitiesRadar