Showing papers by "David C. Fritts published in 1988"
TL;DR: In this article, the velocity and temperature data obtained at the MU Radar Observatory during October and November 1986 are used to examine the character of the motion spectrum in the troposphere and lower stratosphere.
Abstract: Radial velocity and temperature data obtained at the MU Radar Observatory during October and November 1986 are used to examine the character of the motion spectrum in the troposphere and lower stratosphere. It is found that the spectrum is dominated by low-frequency gravity waves with an upward sense of propagation in the lower stratosphere and both upward and downward propagation in the troposphere. Vertical wavenumber spectra of velocity and temperature are used to examine the consistency of the motion spectrum with the saturated spectrum of gravity waves proposed by Smith et al. Results indicate excellent agreement of the observed and predicted velocity and temperature spectra in both amplitude and slope. Vertical wavenumber spectra in area-preserving form reveal a dominant vertical wavelength of ∼2.5 km, systematic variations in energy density and the dominant vertical scale with time, and consistency between the temporal variations of velocity and temperature variance. Taken together, our re...
172 citations
TL;DR: The wave field near the summer mesopause is composed of a superposition of wave motions which act collectively to produce regions in which the wave field is convectively or dynamically unstable as mentioned in this paper.
Abstract: This study utilizes the unique data set obtained during the Structure and Atmospheric Turbulence Environment (STATE) experiment, conducted during June 1983 at Poker Flat, Alaska, to examine the structure and characteristics of the wave field near the summer mesopause. It is shown that the rocket and radar data together permit a much more detailed specification of wave parameters than would be possible using either data set alone. The results of this analysis suggest that the wave field near the summer mesopause is composed, in general, of a superposition of wave motions which act collectively to produce regions in which the wave field is convectively or dynamically unstable. These regions are found to correlate well with zones of enhanced turbulence and small-scale wave activity, suggesting the processes and effects of wave field saturation.
96 citations
TL;DR: In this article, the effect of a vertically propagating, internal gravity wave on the vertical flux of potential temperature (heat) is considered by averaging the local heat flux vector over a potential temperature surface.
Abstract: The effect of a vertically propagating, internal gravity wave on the vertical flux of potential temperature (heat) is considered by averaging the local heat flux vector over a potential temperature surface. This approach gives the wave heat flux a simple physical picture which is not readily apparent from the more common Eulerian formulation. This method also allows the eddy diffusion coefficient to be a function of the phase of the wave. Such a phase dependent eddy diffusion has been previously considered from an Eulerian viewpoint as a model of a convectively unstable gravity wave. Here, the Lagrangian method confirms and corrects the Eulerian results. Earlier work is extended by modeling a constant amplitude “breaking” wave, as well as by considering eddy diffusion coefficients that are asymmetric with respect to the wave breaking region. In all cases studied, 1ocalizing the eddy diffusion to the region of wayebreaking decreases the average heat flux.
57 citations
TL;DR: In this paper, the mesosphere-stratosphere-troposphere radar at Poker Flat, Alaska was used to detect small-scale turbulence and associated larger scale wave structures from rocket probe flights during equinox in spring 1985.
17 citations
TL;DR: In this article, the origin of wintertime mesospheric echoes observed with the mesosphere-stratosphere-troposphere radar at Poker Flat, Alaska, was studied by probing with in situ rocket measurements during echo occurrences in the early spring, 1985.
7 citations
20 Jun 1988
TL;DR: The wave field near the summer mesopause is composed of a superposition of wave motions which act collectively to produce regions in which the wave field is convectively or dynamically unstable as mentioned in this paper.
Abstract: : This study used the unique data set obtained during the Structure and Atmospheric Turbulence Environment (STATE) experiment, conducted during June 1983 at Poker Flat, Alaska, to examine the structure and characteristics of the wave field near the summer mesopause It is shown that the rocket and radar data together permit a much more detailed specification of wave parameters than would be possible using either data set alone Results of this analysis suggest that the wave field near the summer mesopause is composed, in general, of a superposition of wave motions which act collectively to produce regions in which the wave field is convectively or dynamically unstable These regions are found to correlate well with zones of enhanced turbulence and small-scale wave activity, suggesting the processes and effects of wave field saturation Keywords: Gravity waves; Instability; Mesosphere; Thermosphere Reprints
1 citations