Radar and sodar probing of waves and turbulence in statically stable clear-air layers

Abstract

Abstract. This paper reviews the remote sensing of waves and turbulence in statically stable atmospheric layers, utilizing sodar and microwave radar echoes from the small-scale inhomogeneities in gaseous refractive index caused by localized fluctuations in temperature, humidity, and velocity. Scattering theory and sounding methodology are reviewed briefly, and the relative performance of typical radar and sodar systems compared.The main section of the paper takes the form of a summary and discussion of experimental progress since 1969, showing how the echo patterns obtained may be applied to the interpretation of multiple layering, gravity waves, internal fronts and the details of dynamic instability and the genesis of turbulence in stably stratified shear layers. In addition, methods for the measurement of the intensity of the small-scale (~ ~./2) variability of wind, temperature and water vapor from the observed radar or sodar echo intensities, and the use of Doppler techniques for the measurement of mean velocity and turbulence are discussed.

Sodar Probing of Small-Scale Ordered Motions Appeared in the Atmospheric Planetary Boundary Layer

“…The observed results of co-existence of both temperature and wind velocity fluctuations in some confined laminated regions in the lower atmosphere are reported in several papers, for example, by Ottersten et al (1973). The intensity of turbulence is considered to be strong at the laminated regions where sodar echoes are produced.…”

“…5 (a) single layer; July 13, 1973, 22: 00*03: 00JST. by following the works of Ottersten et al (1973) and Wyckoff et al (1973). b) Waves Some sorts of nonlinear waves often occur under the condition of considerable wind shear associated with temperature inversions.…”

Improved observations of turbulence dissipation rates from wind profiling radars

“…These observations will be very useful for the validation of boundary layer parameterizations in numerical weather prediction models and reduce the uncertainty due to these parameters as seen in Yang et al (2016). While profiling lidars and sodars can provide turbulence measurements in the lower levels of the boundary layer (Ottersten et al, 1973;Smalikho and Banakh, 2013), WPRs can supply these measurements to higher levels, above the PBL. Future studies could more closely collocate a WPR with sonic anemometers to analyze the shorter timescales that could possibly be captured by the spectral widths of the WPR measurement volume.…”

“…The spectral width method is also applied to sodars (Ottersten et al, 1973) and Doppler lidar (Smalikho and Banakh, 2013) spectra for dissipation rates, though the structure function and velocity azimuth display methods are more accurate and common (Sathe and Mann, 2013). The radar Doppler spectrum provides the distribution of velocities of backscattering particles within the radar volume, with an average equal to the mean velocity and a spread which indicates the level of turbulence.…”

Turbulent Layers Associated with a Critical Level in the Planetary Boundary Layer

“…Some authors (Thorpe, 1973;Lindzen, 1973;Metcalf and Atlas, 1973) proposed the importance of the critical levels. The fact that turbulence in the stable PBL is induced by small scale Kelvin-Helmholtz waves (K-H waves) when the Richardson number is reduced less than the critical value was found by many observations (Metcalf and Atlas, 1973;Ottersten et al, 1973;Gossard et al, 1970;Gossard et al, 1971). Development and decay processes of K-H waves were investigated in detail by Tanaka (1975).…”