Echoes in clear air from biological scatterers mixed within the resolution volumes over a large region are presented. These echoes were observed with the polarimetric prototype of the forthcoming WSR-88D weather radar. The study case occurred in the evening of September 7, 2004, at the beginning of the bird migrating season. Novel polarimetric spectral analyses are used for distinguishing signatures of birds and insects in multimodal spectra. These biological scatterers were present at the same time in the radar resolution volumes over a large area. Spectral techniques for (1) data censoring, (2) wind retrieval and (3) estimation of intrinsic values/functions of polarimetric variables for different types of scatterers are presented. The technique for data censoring in the frequency domain allows detection of weak signals. Censoring is performed on the level of spectral densities, allowing exposure of contributions to the spectrum from multiple types of scatterers. The spectral techniques for wind retrieval allow simultaneous estimation of wind from the data that are severely contaminated by migrating birds, and assessment of bird migration parameters. The intrinsic polarimetric signatures associated with the variety of scatterers can be evaluated using presented methodology. Algorithms for echo classification can be built on these. The possibilities of spectral processing using parametric estimation techniques are explored for resolving contributions to the Doppler spectrum from the three types of scatterers: passive wind tracers, actively flying insects and birds. A combination of parametric and non-parametric polarimetric spectral analyses is used to estimate the small bias introduced to the wind velocity by actively flying insects.

A new approach for the clear air velocity estimation in weather radar is presented. A combination of nonparametric with parametric spectral analyses allows us to identify and extract multiple processes caused by different scatterer types within a single radar resolution volume. An example of clear air observed using an S-band dual polarization radar is presented. Heretofore, migrating birds and wind-blown insects that are mixed within each resolution volume caused such data to be unusable for meteorological interpretation. In this paper, we construct power spectral densities of polarimetric variables. We use the polarimetric spectral densities to differentiate the scatterer types within the observed radar resolution volume. We demonstrate how our combination of non-parametric and parametric spectral analysis can be used to retrieve the true wind velocity in situations with severe contamination by biological scatterers.

An interdisciplinary and easy-to-understand introduction to the subject, covering fundamental theory and practical applications, and using numerous operational examples. This balanced text will allow you to begin from what the radar observes and move deeper through electromagnetic scattering theory and cloud microphysics to understand and interpret data as it appears on the display. It uses illustrations and figures of real radar observations to convey concepts and theory of atmospheric processes typically observed with weather radar, as well presenting a working knowledge of the radar system itself. In addition to covering fundamentals of scattering and atmospheric physics, topics include system hardware, signal processing, and radar networks. This is the perfect tool for scientists and engineers working on weather radars or using radars and their data, as well as senior undergraduate and graduate students studying weather radars.

The AFGL 10-cm Doppler weather radar was modified to enable the measurement of the differential reflectivity between horizontal and vertical polarizations in addition to the absolute reflectivity and the Doppler mean velocity and spectrum variance. Polarization switching is achieved by means of a diplexer, which separates at the antenna the transmitted signals of two frequencies, 2710 and 2760 MHz, and permits nearly simultaneous transmission of signals of orthogonal polarizations. Signals of these frequencies can be transmitted either with horizontal and vertical polarization, respectively, or with left and right circular, polarization, respectively. We describe the design and performance of the diplexer and the performance of the real-time data processor, present examples of meteorological measurements, and discuss future developments of the radar system. Keywords: Polarization diversity weather radar, Dual polarization radar, and Polarization switching.

This 2001 book provides a detailed introduction to the principles of Doppler and polarimetric radar, focusing in particular on their use in the analysis of weather systems. The design features and operation of practical radar systems are highlighted throughout the book in order to illustrate important theoretical foundations.

Weather forecast estimation has been a matter of analysis for many years. The arrival of dual polarization radars meant an improvement due to the incorporation of new variables. This project illustrates how to obtain the standard and new meteorological variables (Reflectivity, Doppler Velocity, Spectrum Width, Differential Reflectivity, Co-Polar Correlation Coefficient and Differential Propagation Phase). Reflectivity and Doppler velocity appear to be more advantageous because they are more consistent since the Spectrum Width is easily corrupted. Variables retrieved from the dual polarization radars happen to be even more reliable than the standard ones because most of them are independent from miscalibrations and attenuations. It also analyzes two different noise identification methods in order to estimate the noise floor. One of them based on the Co-Polar Correlation Coefficient characteristics that, for most of the cases, show a better performance than the other method based on three different features that threshold the noise.

This book reviews the principles of Doppler radar and emphasizes the quantitative measurement of meteorological parameters. It illustrates the relation of Doppler radar data and images to atmospherix phenomena such as tornados, microbursts, waves, turbulence, density currents, hurricanes, and lightning. Radar images and photographs of these weather phenomena are included. Polarimetric measurements and data processing An updated section on RASS Wind profilers Observations with the WSR-88D An updated treatment of lightning Turbulence in the planetary boundary layer A short history of radar Chapter problem sets