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Refraction of 50‐MHz radar waves in a realistic ionospheric model
Author(s) -
Watermann Jurgen
Publication year - 1990
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs025i005p00805
Subject(s) - radar , refraction , ionosphere , earth's magnetic field , physics , electron density , optics , ray tracing (physics) , incoherent scatter , geology , geophysics , computational physics , magnetic field , electron , telecommunications , computer science , quantum mechanics
The role of ionospheric refraction in observing coherent radar backscatter from the auroral E region has recently come into the discussion again when it was proposed that for 50 MHz radars refraction efficiently brings the radar beams to virtually perpendicular intersection with the geomagnetic field at the scatter location and thus explains a number of otherwise puzzling results. However, without a thorough calculation of the actual refraction under the given ionospheric conditions its effect cannot be assessed accurately since it is not simply the maximum electron density and layer tilt but rather the product of density gradient and beam propagation distance measured along the contours of constant density which determines the refraction. In order to study typical refraction features a ray tracing computer program was applied to an ionospheric model consisting of an auroral arc with high electron density imbedded in a horizontally stratified ionosphere. It turns out that, when adapted to the Canadian BARS Red Lake radar, a sufficiently enhanced electron density within the arc can bring the radar beam to virtually perpendicular intersection with the geomagnetic field at ranges exceeding the distance from the radar to the centre of the arc by about 100 to 150 km.