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  • Author or Editor: R. B. Chadwick x
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E. E. Gossard
,
R. B. Chadwick
,
W. D. Neff
, and
K. P. Moran

Abstract

The use of ground-based clear-air Doppler radars to observe the structure of elevated atmospheric layers and associated flux quantities is described. Case studies in which radar and balloon data were available are analyzed. Doppler second-moment (velocity variance) data are used to calculate turbulent kinetic energy dissipation rate ε. Velocity variance, refractive index structure parameter and wind shear are used to estimate the refractive index gradient across elevated weather-frontal interfaces. A case is analyzed in which both acoustic-sounder and radar-sounder data are available, so profiles of structure parameter of both temperature and humidity can be deduced and used to calculate the fluxes of heat and moisture within the frontal interface. The fluxes deduced from radar data are compared with corresponding in situ measurements made by aircraft in other geographical regions. The relationship between the turbulent Prandtl number and the Richardson number emerges as very important to the generalization of the technique to the whole stable atmosphere.

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Earl E. Gossard
,
Russell B. Chadwick
,
Thomas R. Detman
, and
John Gaynor

Abstract

Radars and acoustic sounding systems sense properties of the turbulence structure of the atmosphere. If atmospheric turbulence can be related to the mean gradient parameters, Doppler radars and acoustic sounders can provide information about height profiles of quantities such as temperature and refractive index as well as wind in stable regions of the atmosphere. In this paper turbulent and mean quantities were measured on the 300 m meteorological tower at the Boulder Atmospheric Observatory near Erie, Colorado, and the relationships between the turbulent and mean gradient quantities were examined in order to evaluate hypotheses for simplifying the kinetic energy balance and refractive index variance equations. FM-CW radar measurements of backscattered power and Doppler spectral width were also made for comparison with tower-measured refractive index spectra and Doppler velocity spectra. Height distributions of the turbulent dissipation rate within stable layers are shown and viscous cutoff radar wavelengths calculated.

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J. C. Kaimal
,
N. L. Abshire
,
R. B. Chadwick
,
M. T. Decker
,
W. H. Hooke
,
R. A. Kropfli
,
W. D. Neff
,
F. Pasqualucci
, and
P. H. Hildebrand

Abstract

Three in-situ and five remote sensing techniques for measuring the height of the daytime convective boundary layer were compared. There was, as a rule, good agreement between the different systems when the capping inversion was steep and well defined, and some variability when the stratification was not so sharply defined. Two indirect methods for estimating boundary-layer heights from the length scales of convective motions in the layer are also discussed.

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