Doppler sodar and radar wind-profiler observations of gravity-wave activity associated with a gravity current

Abstract

Observations have been used to conduct a case study of a gravity current entering into an environment containing a nocturnal inversion and an elevated neutral layer. It is concluded that the gravity current might have originated either as a scale-contracted cold front or as a gust front resulting from thunderstorm outflows observed very near the leading edge of a cold front. Despite this ambiguity, the detailed vertical structure of the gravity current itself is well resolved from the data. Although only wave periods, and not phase speeds or wavelengths, are directly measured, it is possible to make resonable inferences about wave excitation mechanisms and about the influence and control of ambient stratification on wave-field characteristics. Both Kelvin-Helmholtz waves generated in the regions of high wind shear found in association with the gravity current and lee-type waves forced by the gravity current acting as an obstacle to opposing prefrontal flow are identified. -from Authors