Polar Cap Plasma Convection Measurements and their Relevance to the Real-Time Modeling of the High Latitude Ionosphere

• Main Authors: Buchau, Jurgen, Anderson, David N., Weber, Edward J., Reinisch, Bodo W., Dozois, Claude
• Other Authors: AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA
• Format: Text
• Language: English
• Published: 1987
• Subjects: Atmospheric Physics; *IONOSPHERE; *CONVECTION; *PLASMAS(PHYSICS); MEASUREMENT; MAGNETIC FIELDS; COMPUTATIONS; REAL TIME; GREENLAND; THEORY; DRIFT; PROFILES; REVERSIBLE; PATTERNS; IONOSPHERIC MODELS; HIGH LATITUDES; QUIET; REPRINTS; POLAR REGIONS; VELOCITY; ELECTRON DENSITY; PE61102F; WUAFGL464330805; Greenland; Qaanaaq; Thule
• Online Access: http://www.dtic.mil/docs/citations/ADA205703; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA205703

Plasma convection measurements, using Digisonde ionospheric sounders, have been conducted. The plasma convection or ionospheric drift measurements conducted at Thule and Qaanaaq during campaigns from Winter 1983/84 to present provide evidence, that antisunward convection dominates in the polar cap with velocities typical between 300 and 900 m.sec. Drift shears were observed during periods of arc-transition (quiet magnetic conditions). Observations of the plasma drift at Goose Bay show, a drift reversal from westward to eastward around midnight CGLT. Observations at Argentia, typically a suboval/trough station, provide evidence under magnetically disturbed conditions for the midnight reversal of the antisunward flow pattern. However, the data are less consistent under magnetically quiet conditions. The proximity of the station to the boundary between corotating and convecting plasma may at times affect the consistency of the measurements. Recent theoretical calculations of electron density profiles within the high latitude/polar cap ionosphere demonstrate that the diurnal foF2 variation observed at Thule, is controlled by the plasma convections pattern and the associated drift velocities. The model calculations for Bz < 0 and Bz. approx. 0 show factor 2 to 3 differences in Nmax over Thule, supporting the stated importance of convection pattern and velocity measurements for the modelling of the high latitude ionosphere. Reprints. Pub. in The Effect of the Ionosphere on Communication, Navigation, and Surveillance Systems Based on Ionospheric Effects Symposium p659-673, 5-7 May 1987.