Upgrade and Operational Support for an MF Radar at Rarotonga

Northwest Research Associates, Incorporated, Seattle WA

Investigators

Abstract

This proposal would provide for the modernization of an existing MF radar at Rarotonga (21.5S, 160W) in the tropical southern Pacific and operational support for two years. Under this proposal, a new data acquisition system would be installed and the 8-bit receivers upgraded to 12- or 16-bit digitization. The operational height range of the radar (currently 80-98 km) will be expanded downward to span most of the mesosphere (~60-98 km), and the measurement accuracy above 90 km will be improved. The dynamic range of the existing 8-bit digitization has been shown to be grossly inadequate for mesospheric MF radar returns. A variety of validation and technical studies have demonstrated that receiver saturation above 90 km (which is nearly unavoidable with 8-bit operation) results in wind magnitude under-estimates. This source of bias will be eliminated and the upgrade will make the radar more reliable and increase its overall performance. Rarotonga is situated in a key latitude belt where there are presently no measurement capabilities and is almost precisely conjugate (same longitude and opposite latitude) to an existing MF radar at Kauai, Hawaii. The Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite mission (beginning in May 2000) will foster combined data analysis from satellite instruments and multiple ground-based sites. For correlative global studies of phenomena like the diurnal tide it is essential that the participating radars provide unbiased winds with similar performance across systems.