Open Access. Powered by Scholars. Published by Universities.®

Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

Series

1984

Ionosphere

Articles 1 - 5 of 5

Full-Text Articles in Physics

Ionospheric Currents And F-Region Plasma Boundaries Near The Dayside Cusp, S Vennerstrom, E Friis-Christensen, T S. Jorgensen, C E. Rasmussen, C R. Clauer, Vincent B. Wickwar Jan 1984

Ionospheric Currents And F-Region Plasma Boundaries Near The Dayside Cusp, S Vennerstrom, E Friis-Christensen, T S. Jorgensen, C E. Rasmussen, C R. Clauer, Vincent B. Wickwar

All Physics Faculty Publications

Observational evidence of the location of a dayside high‐latitude ionospheric current (DPY current) with respect to the different regimes of the high‐latitude magnetosphere is obtained by analyzing data from the magnetometer chain along the west coast of Greenland in conjunction with simultaneous measurements from the newly established incoherent‐scatter radar facility at Sondre Stromfjord. The latitudinal location of the DPY current is compared with the location of the maximum F‐region electron temperature and with the location of the plasma convection reversal from sunward to antisunward. The maximum in the F‐region electron temperature roughly coincides with the ...


Plasma Characteristics Of Polar Cap F-Layer Arcs, H C. Carlson Jr., Vincent B. Wickwar, E J. Weber, J Buchau, J G. Moore, W Whiting Jan 1984

Plasma Characteristics Of Polar Cap F-Layer Arcs, H C. Carlson Jr., Vincent B. Wickwar, E J. Weber, J Buchau, J G. Moore, W Whiting

All Physics Faculty Publications

First results are reported of a comprehensive campaign to measure ionospheric structure and dynamics of nighttime polar cap F‐layer or F‐region arcs. Airborne optical and digital ionosonde data were collected simultaneously with ground based incoherent scatter radar data, continuously over many hours in time and 500 to 1000 km in space. Polar cap F‐region sub‐visual auroral arcs, which are commonly observed during quiet magnetic conditions, are found to represent boundaries (or shears) in the polar cap plasma circulation pattern. F‐region electron concentration enhancements are found in these features and can be of significance to polar ...


Very High Electron Temperatures In The Daytime F-Region At Sondrestrom, W Kofman, Vincent B. Wickwar Jan 1984

Very High Electron Temperatures In The Daytime F-Region At Sondrestrom, W Kofman, Vincent B. Wickwar

All Physics Faculty Publications

Sondrestrom observations show that a characteristic F‐region signature of the interaction between the magnetosphere and ionosphere is a narrow band of elevated electron temperatures. Its location is associated with the ion convection reversal in the morning and evening convection cells. Typically, near 500 km altitude, the temperature is 3500 to 4000 K. However, on 24 April 1983, a geomagnetically very active day with Kp values of 6‐ during the period of interest, the electron temperature reached 6000 K in the afternoon convection reversal. The ion velocities were between 1 and 2 km/s on both sides of the reversal ...


Initial Millstone Hill, Sondrestrom, And Hilat Observations Of Thermospheric Temperatures And Frictional Heating, W L. Oliver, J C. Foster, J M. Holt, G B. Loriot, Vincent B. Wickwar, J D. Kelly, O De La Beaujardiere, P F. Bythrow, D I. Meng, F J. Rich, R E. Huffman Jan 1984

Initial Millstone Hill, Sondrestrom, And Hilat Observations Of Thermospheric Temperatures And Frictional Heating, W L. Oliver, J C. Foster, J M. Holt, G B. Loriot, Vincent B. Wickwar, J D. Kelly, O De La Beaujardiere, P F. Bythrow, D I. Meng, F J. Rich, R E. Huffman

All Physics Faculty Publications

Elevation scan observations made by the Millstone Hill and Sondrestrom incoherent scatter radars are combined to provide extended latitudinal coverage of thermospheric measurements. Maps of the latitudinal and temporal structure of the exospheric temperature are presented for two 24‐hour periods over the latitude range 45 to 72 degrees north. On the magnetically quiet June day the Millstone and Sondrestrom data formed a consistent picture of thermospheric structure. On the disturbed July day the two radars observed very different behavior, with Millstone Hill observing strong, long‐lived ion frictional heating events but Sondrestrom observing more quiescent behavior. Comparison with HILAT ...


Dayside Red Auroras At Very High Latitudes: The Importance Of Thermal Excitation, Vincent B. Wickwar, W Kofman Jan 1984

Dayside Red Auroras At Very High Latitudes: The Importance Of Thermal Excitation, Vincent B. Wickwar, W Kofman

All Physics Faculty Publications

Extensive radar observations have been made from Sondrestrom of the F region in the daytime sector between 70 and 79° Λ. Regions of enhanced electron temperature and electron density are found in close association with the velocity reversal in the morning and afternoon convection cells. From the radar measurements, calculations are made of the contributions to the atomic oxygen emission at 6300A from dissociative recombination and thermal excitation. The latter mechanism, in particular, in the enhancement regions gives rise to intensities that are comparable to those observed at very high latitudes during the past decade.