The interaction between an internal gravity wave and the planetary boundary layer. Part I: The linear analysis

Using the data obtained at the Boulder Atmospheric Observatory (BAO), we have analysed a gravity wave‐turbulence event, which occurred on 18 September 1978. A 300m tower was equipped with various sensors at eight different levels and provided information on the vertical structure of the disturbance to an unprecedented degree. These data were complemented by measurements from a nearby microbarograph network which allowed us to determine the period and horizontal wavelength of the disturbance. It was the rather accurate determination of the period of the gravity wave and its near monochromaticity that made possible the utilization of the phase average operator in separating the periodic and turbulent components of the field variables. In this paper, we concentrate on describing the wave field and on comparing it with a linear model, deferring to a second paper the discussion of the effect of the periodic disturbance on the coexisting turbulence. We show that a linear model adequately describes the observed parameters (period and horizontal wavelength) and the vertical structure of the fluctuations in the temperature and horizontal and vertical velocity components.