Use of the Atmospheric Electric Field for Terrain Avoidance
JOHNS HOPKINS UNIV LAUREL MD APPLIED PHYSICS LAB
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Both natural and man-made orographic protrusions perturb the normally vertical atmospheric electric field. The magnitude and direction of the electric field perturbations have been computed for such protrusions as walls and small mountains. A limited number of measurements made near ground level and from an instrumented aircraft show that the atmospheric field in the neighborhood of orographic protrusions behave as expected. From theoretical calculations of the atmospheric field and ground-based and laboratory measurements, the authors infer that an aircraft or missile in flight would be able to detect perturbations useful in terrain avoidance at ranges of five times the height of a typical mountain ridge if the vehicle is on a horizontal flight path lying well below the ridge altitude. The range of atmospheric and terrain conditions for which this inference is valid cannot be accurately specified on the basis of data now available.
- Atmospheric Physics