Valery Melnikov

Doppler Velocities at Orthogonal Polarizations in Radar Echoes From Insects and Birds

The differential Doppler velocities (DDVs) measured with weather radar at horizontal and vertical polarizations in echoes from insects and birds are considered. In weather echoes, DDV is usually less than 0.5 ms- 1, whereas in echoes from flying birds and insects, it can reach 5-7 ms- 1. Such large difference can be used as an additional parameter in distinguishing between weather and nonmeteorological echoes. It is shown that large values of DDV pertain to multipeaked Doppler spectra with different spectral differential reflectivity values in the peaks.

Resonance Effects Within S-Band in Echoes From Birds

It is shown that the scattering resonance effects in echoes from migrating birds are so strong that a 10% frequency deviation within S-band can result in more than 10-dB changes in reflectivity values. Differential reflectivity values from adjacent polarimetric WSR-88D weather radars operating at offset frequencies can differ by several decibels in “clear air” echoes.

A Method to Increase the Scanning Rate of Phased-Array Weather Radar

To increase the scanning rate of phased-array radar by a factor of two or more, the contiguous transmission of two or more pulses toward two or more directions and simultaneous reception of weather echoes from those directions is employed. However, if there are strong gradients of reflectivity, mainlobe-to-sidelobe coupled echoes contaminate wanted mainlobe-to-mainlobe (m-m) coupled echoes and limit the accurate analysis of weather. To retrieve m-m echoes, a technique is derived that restores wanted m-m voltages for antenna sidelobe levels as high as -30 dB and the difference in echo power of 100 dB for two simultaneously sampled beam directions. The technique is demonstrated using data collected with the WSR-88D radar and simulating PAR operations.