Laser remote sensing of species concentrations and dynamical processes

摘要

A review of current lidar techniques summarizes present capabilities to: (1) measure atmospheric concentrations of most major and several minor molecular species using Raman scattering and DIAL techniques, (2) detect and measure concentrations of certain trace level species, (3) characterize active dynamical processes in the troposphere based upon using water vapor as a tracer, and (4) describe interesting thermodynamic properties based upon rotational Raman temperature profiles, multi-wavelength aerosol distributions, and changes in the phase states of water. Advances in lasers and detectors have extended the range of wavelengths available through the ultraviolet, visible, and infrared spectrum by using tunable laser techniques and supercontinuum broad spectrum lasers. Prior studies are reviewed, several applications for the technology are suggested which extend the techniques proposed to future investigations. In particular, the extension of tunable laser sources into the ultraviolet region has opened opportunities to use resonance Raman techniques, which provide greatly increased sensitivity for certain molecular species, such as hydrocarbons. The developments of supercontinuum lasers and tunable OPO lasers has enabled long-path trace concentration measurements of molecular spectra lines to detect and measure the concentrations of many species, as well as to distinguish any interfering species.