Preliminary quantitative analysis of S-band FMCW radar data from atmospheric observation

Abstract

For more than three decades, S-band, frequency-modulated, continuous-wave (FMCW) radars have been used to study the structure and dynamics of the atmospheric boundary layer (ABL). With tremendous sensitivity and spatial resolution compared to their pulsed counterparts, these systems have been successfully applied to detection of clear-air turbulence in the lower atmosphere. In this study, data collected during field experiments by the University of Massachusetts' high-resolution S-band FMCW radar is used to illustrate and discuss system performance. S-band FMCW radar is sensitive to both Bragg scatterers (from spatial variations in radio refractive index of air) and Rayleigh scatterers (strong point-like echoes from nonatmospheric targets), and in the convective boundary layer Rayleigh echo appears to dominate the observed vertical profile of mean reflectivity. A postprocessing technique, which is based on single-lag covariance differences between the clear-air echo and Rayleigh echo, is applied to time-series of backscattered power to estimate clear-air component of the backscatter and remove the influence of Rayleigh scatter on the vertical profiles. The preliminary results of a quantitative analysis (mean and statistical distribution) of radar reflectivity are presented and compared with theoretical predictions about the convective ABL.