Doppler imaging system: an optical device for measuring vector winds. 1: General principles.
The Doppler imaging system is a Fabry-Perot spectrometer adapted to use a spatially sensitive photon detector to provide each of several instrument stations with a full 2-D imaging capability. Line-of-sight winds are determined from the Doppler shifts for each spatially defined pixel. Full vector wind fields may be obtained using three instrument stations and, at the cost of increased data processing and a priori information requirements, from two or even one instrument station. The proposal outlined here is for a bistatic system with ground-based instruments located at stations separated by some 200 km, each using wide-angle foreoptics(120 degrees) to observe upper atmospheric emissions in the vicinity of the auroral oval. Such a system should be capable of measuring winds, using, for example, the OI 630-nm emission, on a 2-D spatial grid, over a region up to approximately 800-km diam, with 50-km square pixels, and yield wind measurements with accuracies +/-20 m/sec in integration times of approximately 10 min.
Rees
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University College London, Department of Physics & Astronomy, Gower Street, London WC1E 6BT, UK.
Greenaway
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