Radar Observations of the Clear Atmosphere

Refractive index perturbations of half the radar wavelength in scale mostly contribute to atmospheric radar backscattering. From the Doppler observations of upper atmosphere, vertical profiles of turbulence parameters such as energy dissipation rate and vertical eddy diffusivity can be deduced on certain conditions. Combined with the radar acoustic sounding system (RASS), atmospheric radar measurements can also provide vertical profiles of background virtual temperature and water vapor.In this chapter, the notion of radar detectability is first shown. Basic techniques used to retrieve wind velocity from radar measurements are then discussed. Next, the methods used for estimating turbulence parameters and other physical parameters obtained from atmospheric radar measurements are discussed. Finally, radar interferometric techniques for improving the spatial resolution are described.