A Beam De-Broadening Algorithm for Atmospheric Radar

Abstract

Measuring the variance of the velocity of atmosphere $\sigma _{turb}^2$, which is proportionally linked to the energy dissipation rate, is a common role given to MST radar. However, the spectral width $\sigma _{obs}^2$, which is directly observable with a radar, contains not only the contribution from turbulence itself but also some measurement biases. Among them, beam broadening $\sigma _{beam}^2$, which is the projected components of the mean wind velocity to the off-center sensitivity of the radar beam, is the major factor. A number of studies have been conducted to evaluate the beam broadening under an assumption that the antenna beam is conical and well defined by its beam width. However, this assumption is not applicable to nonstandard radar configurations that have distributed or asymmetric antenna array and thereby resulting asymmetric beampatterns. We present a comprehensive mathematical theory and practical algorithm to evaluate $\sigma _{beam}^2$ that is applicable to any antenna structure.