Preliminary results of atmospheric acoustic sounding at Calgary

Abstract

Operation of a monostatic acoustic sounder on the campus of The University of Calgary for the period March to September, 1976, has provided data on the atmospheric boundary layer over Calgary. The formation and dissipation of the nocturnal temperature inversion layer leaves a clear signature in the sounder records. A trend is discerned in which the nocturnal layer tends to form at sunset, whereas convective instability is established some 2-3 hours after sunrise. Comparison of sounder records with an extensive set of radiosonde temperature profiles has shown that the height of the inversion layer can be determined reliably when a single, dark, ground-based return is visible on the sounder charts. On many occasions, however, the sounder detects multiple structures in the atmosphere. In these cases, it is difficult to establish a systematic correspondence of the turbulent structure as observed in the sounder records with the temperature profile as observed by the radiosonde.

Acoustic Sounding on the Lower Atmospheric Inversion Layer

“…Both reinforce the findings in studies by Goroch (1976), Hicks et al (1977) and von Gogh and Zib (1978). (3) The heights of the lifted inversion The facsimile record sometimes shows an isolated echo layer as shown in Fig.…”

“…This relationship has been studied by many researchers; Cronenwett et al (1972), Wyckoff et al (1973), Fukushima et al (1974, Parry et al (1975), Hicks et al (1977) and Clark et al (1977). The most common feature for each record is a weed type echo which is obtained during daytime with strong insolation.…”

“…4. The top heights of the lifted inversion are compared with temperature profiles by Hicks et al (1977) and von Gogh and Zib (1978). Fig.…”

“…Acoustic sounding record have been compared with the temperature and wind profiles. Temperature profiles to be compared with the simultaneous acoustic record were obtained by means of free-flying balloon borne radiosonde (Wyckoff et al 1973;Parry et al 1975;Goroch, 1976;Hicks et al, 1977) and tethered balloon borne thermometer (von Gogh and Zib, 1978;Nater and Richner, 1977 (1) Acoustic sounder The acoustic sounder used in this study is similar to that reported by Hayashi et al (1978). The blockdiagram of the sounder is shown in Fig.…”

Sodar observations of the nocturnal boundary layer at Kharagpur, India

“…Following the theoretical work of Tatarskii (1961) and Monin (1962), wherein acoustic scattering in air was considered to depend primarily on fluctuations in temperature and wind velocity, and using the Kolmogrov spectrum of turbulence, Little (1969) expressed scattering cross section as a function of scatter angle and structure parameters of wind and temperature fluctuations. Investigations comparing the height of the ground-based sodar echograms with the simultaneously recorded height of the inversion layer using in situ techniques have shown that the acoustic sounder can be confidently used to measure inversion heights for single, unambiguous ground-based layers (Wyckoff et a/., 1973;Goroch, 1976;Hicks et al, 1977;Von Gogh et al, 1978;Singal et al, 1979;Singal et al, 1986).…”