G. I. Khlopov

Retrieval of rain intensity by three-frequency radar sensing

Three-frequency approach for radar sensing of liquid precipitation is proposed, which permits to retrieve a spatial profile of rain intensity. Results of numerical simulation of three-frequency radar sensing of rains are presented for different sets of operating wavelengths of radar and for range of rain intensity (0÷30) mm/h. It is shown that use of millimeter wavelengths is not reasonable due to strong signal attenuation at the large distances and/or for large values of rain intensities. However application of longer wavelengths permits to reduce influence of attenuation and to decrease measurement errors of rain intensity. In particular, maximal retrieval error of rain intensity is not more than 7 %.

Profiling of rain parameters by dual frequency radar

The dual frequency method for measurement of profile of rain parameters is presented. The procedure takes into account signal attenuation in rain and permits to eliminate measurement ambiguity for small rain intensity. The results of numerical simulation of a rain sounding for nonuniform profile confirm the validity of the method proposed.

Measurement of range and speed of high-speed targets by millimeter wave pulse radar

Possibility of unambiguous simultaneous assessment of range and speed using pulse millimeter wave radar. It is shown that for high-speed targets it is impossible to measure speed and distance simultaneously using coherent pulse packet as well as use of wobble of repletion frequency. Therefore the use of radio pulses with high repetition frequency and stochastic frequency modulation is proposed and their properties are studied.

Experimental study of atmosphere turbulence by using bicoherence-based signal processing technique

Novel bispectrum-based signal processing technique is proposed for analysis of turbulence contained in the atmosphere. Novel classification features evaluated in the form of bicoherence estimates of the weather radar signals backscattered by volume-distributed atmospheric formations are suggested for solving the discrimination problem of the safe laminar meteorological formations and zones of turbulence dangerous for the aircraft flights. Results of experimental measurements performed by non-coherent double-frequency weather radar operating in millimeter and centimeter wavelength ranges are represented and discussed.

Combined use of radiometer and double frequency radar for measurement of rain intensity

Active-passive method for measurement of rain intensity is proposed based on double frequency radar and radiometer. Numerical simulation of active-passive remote sensing of uniform rains was performed for radar wavelengths of 8.2 mm, 3.2 cm and for radiometer - 3.2 cm. It was shown that measurement error of proposed method does not exceed 10% in the range of rain intensity 0 ÷ 30 mm/h.

Experimental study of atmosphere turbulence by using bispectral analysis

Novel bispectrum-based signal processing technique is proposed for analysis of turbulence in atmosphere. Classification features obtained from magnitude bispectrum estimations are represented for recognition and discrimination of laminar and turbulent clouds. Results of experimental study performed by non-coherent double-frequency weather radar are presented.