The article presents a review of the existing remote snesing methods for experimental study of coherent structures in the fields of temperature, wind speed, refractive index, and admixture concentrations. The physical principles, underlying some methods developed recently are described. The use for these purposes such devices as sodar, lidar, radar, scidar, radiometer, and also occultation techniqes and tomographic techniques is discussed. The advantages and restrictions of different methods, altitude ranges of their applicatbility, and also representativeness of the results obtained are considered. The examples of visualization of vortical, layered and wavy structures and experimental estimates of their parameters are given. The origin of structured turbulence in the atmosphere is discussed. A classification of various forms of coherent structures is offered. Systemization of recently published experimental estimates of their parameters in the lower and middle atmosphere is made.
The results of an experimental investigation of optically active turbulence in the atmospheric boundary layer (ABL) over Moscow are given. Both quantitative and qualitative data on the ABL structure are obtained due to remote acoustic sensing. Statistical data are given on daily variations in the mean value of the refractive index structure parameter Cn2 (for winter and summer), on the vertical profiles of Cn2 for different types of the ABL thermal stratification and also on the seasonal occurrence of the type of stratification. The distinctions in the behavior of optical turbulence over a city and a homogeneous terrain are discussed as well as the deviations of the real profiles of Cn2 in the urban ABL from the known model representations.
The results of long term experiment on twenty-four-hour observations of the atmospheric boundary layer (ABL) parameters with acoustic sounders (sodars) in Moscow during a period from January 1989 until December 1991 are presented. This experiment also included simultaneous sodar observations at three points within the city and suburbs during three months in different seasons. The statistics of the boundary layer parameters as well as the data on their spatial variations over the city are discussed. The data of the first wind measurements in the ABL over the center of the city are presented. The comparison of local concentrations of two pollutants and the parameters measured by sodar (the mixing height and the wind speed) are given.
The technique and instrumentation for remote (ground) measurements of the optical refractive index structure parameter Cn2 using an acoustic sounder (sodar) is described. The procedure of the sodar absolute calibration is discussed. The comparison between the sodar and in situ measurements suggests that the errors which are inherent to the method proposed are essentially less than the space-time variability of Cn2. The results of the study of optically active turbulence in the atmospheric boundary layer above mountainous and urban areas are presented.