초록 ▼

The detection and warning of microbursts, low level wind shear, and other weather disturbances, which are hazardous to aircraft operations and to the public at large, are accomplished with either an airport surveillance radar (ASR) or a multi-beam Doppler radar. ASR Doppler systems normally operate

The detection and warning of microbursts, low level wind shear, and other weather disturbances, which are hazardous to aircraft operations and to the public at large, are accomplished with either an airport surveillance radar (ASR) or a multi-beam Doppler radar. ASR Doppler systems normally operate to receive one of two relatively large vertical fan beams having different elevation angles but which overlap one another so that they have equal gains at an elevation angle, called the null, at a relatively low angle, for example 5°. Below this null, the low beam antenna gain exceeds that of the high beam, and conversely above it. Accordingly, by subtracting the high beam Doppler spectrum from that on the low beam, a Difference Doppler Spectrum (DDS) is produced which is positive below the null and negative above. The velocity bounds of the positive portion of the DDS provide the wind speed components at the null and at heights near the surface. These wind speed components are then utilized to measure and map radial and horizontal shear, the boundaries of the disturbance and other signatures such as vertical shear and turbulence and the rate of change of all the parameters, thereby permitting the detection of the location and track of the disturbance. A multi-beam Doppler radar can be utilized to perform similar functions of measuring the mean Doppler velocity, Doppler spectral breadth, and reflectivity simultaneously at all elevations. Both systems provide effective enhancements in signal to clutter ratio through pattern recognition and motion detection.

대표청구항 ▼

A radar method of detecting hazardous weather phenomena associated with rapidly descending events such as a downburst and which comprises the steps of: radiating at least one beam sufficiently large in vertical breadth to illuminate the aras encompassed by a plurality of vertically displaced receivi

A radar method of detecting hazardous weather phenomena associated with rapidly descending events such as a downburst and which comprises the steps of: radiating at least one beam sufficiently large in vertical breadth to illuminate the aras encompassed by a plurality of vertically displaced receiving beams from an antenna scanned in azimuth toward a region of scatterers; receiving the echo powers from said plurality of beams, said echo powers being representative of the average reflectivity of the scatterers in said beams; determining the measure of the relationship between the echo powers between said beams at successive elevations at all range bins of a radar system, said relationship providing information representative of the vertical profile of average reflectivity of weather phenomena detected by said radar system; storing a sequence of said measures for successive scans of said antenna; determining the time difference of said measures; and generating a time history of said measures, thereby providing an early indication of rapidly changing reflectivities and profiles associated with a descending downburst and providing a changing pattern corresponding to an evolving downburst and other weather hazards.