Simultaneous Lidar and Refractometer Soundings of Layer Structure in the Troposphere

Abstract

THE structure of isothermal and inversion layers in the troposphere is of interest in many aspects of radiometeorology. These layers, which can often be detected by centimetric radar, are now known to occur more frequently than many workers had previously thought^1,2. They are usually associated with large variations in humidity and therefore in radio refractive index. Consequently, they often cause relatively strong reflexion or scattering in very high frequency radio propagation beyond the horizon. The structure of these layers and the nature of atmospheric turbulence within and near them are, however, complex subjects on which much further research is required. We summarize here some preliminary experiments (carried out by the Radio and Space Research Station in October 1968 at Cardington, Bedfordshire) in which simultaneous soundings of elevated inversion layers were made with balloon-borne refractometers and thermometers and ground-based lidar (pulsed laser). Some earlier experiments³ showed that stratified echoes, possibly associated with inversions, could be detected by lidar probing of the troposphere. The purpose of our experiments was to study the precise location of the aerosols causing the lidar echo in relation to large changes in the vertical distribution of refractive index, temperature and wind velocity. Such information is valuable in developing improved models of tropospheric structure and in extending theories of turbulent motion.