Beam Filling Loss Adjustments for ASR-9 Weather Channel Reflectivity Estimates
Abstract
The FAA is deploying over 100 new airport surveillance radars (ASR-9) across the country. In contrast to earlier ASRs, the ASR-9 utilizes a separate digital weather processing channel to provide air traffic controllers with timely, calibrated displays of precipitation intensity. The ASR-9 utilizes dual selectable fan-shaped elevation beams designed to track aircraft over a large volume. As a consequence, weather echoes received from these fan-shaped beams represent vertically-averaged quantities. If the precipitation only partially or non-uniformly fills the beam, then the vertically integrated reflectivity may underestimate the actual intensity of the storm. The ASR-9 weather channel corrects for this by adjusting the range-dependent six-level reflectivity thresholds. The appropriateness of the currently implemented correction has not been carefully examined and may require modification to take into account regional and morphological variability in storm structure. This reports discusses the method used to derive new beam filling loss adjustments. An extensive database of volumetric pencil-beam radar data were used in conjunction with our ASR-9 simulation facility to derive adjustments aimed at calibrating the precipitation intensity reports to the maximum perceived hazard. Results from this calibration indicate that a single correction is appropriate for all sites and intensities. The new corrections yield substantially improved results over the current corrections in producing these reflectivity reports. Keywords: Airport radar systems; Meteorological radar.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 23, 1990
- Accession Number
- ADA228654
Entities
People
- C. D. Engholm
- S. W. Troxel
Organizations
- Massachusetts Institute of Technology