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GENE L. WOOLDRIDGE

Abstract

High-resolution pictures obtained with a handheld camera during the earth-orbiting photographic mission of the Apollo 9 spacecraft provided a unique opportunity to map the areal extent of gravity waves over the southwestern United States. The gravity waves were manifested in thin layers of middle- and high-cloud patterns over the rugged terrain of Arizona, Colorado, and New Mexico.

Zonal shearing stress gradients in stably stratified air flowing over rugged mountain terrain indicated very large subgrid-scale vertical fluxes of zonal momentum. Maximum stress values of several tens of dynes·cm−2 (10−3 mb) were calculated for the lower tropospheric layers where the air flowed over the high Rocky Mountains of central New Mexico. The vertical fluxes of zonal momentum were directed upward to tropopause levels when extensive areas of gravity waves covered eastern Arizona, New Mexico, and western Texas.

The potential energy contained in the wave population attained values through the troposphere as high as 9.3× 105 J·m−2; this potential energy was a substantial part of the atmospheric energy budget. The residual “dissipation” term in the kinetic energy budget indicated a subgrid-scale flux of energy downward from the lower stratosphere concurrent with the upward flux of zonal momentum in the troposphere. Atmospheric turbulence exhibited a maximum during the wave occurrence, diminishing gradually thereafter.

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Gene Wooldridge and E. R. Reiter

Abstract

From GHOST balloon data obtained over the Southern Hemisphere at the 200-mb level, phase velocities of cyclone waves were found to vary between 6.3 and 9.2 degrees of longitude per day. Spectrum analysis of the relative velocities of balloon pairs, measured with respect to their common center of gravity, yielded a spectrum peak in the v component near frequencies of 1/52 hr, and a “−3” spectrum slope at higher frequencies. (The latter may be contaminated by a spline function smoothing technique.) Spectral densities in v were found to be slightly larger in summer than in winter, while densities in u were half as large in summer than in winter. Significantly stronger anisotropy of flow prevails at cyclone wavelengths in the Southern than the the Northern Hemisphere, with the v perturbations exceeding the zonal flow perturbations. GHOST balloon cospectra yielded similar results of momentum transport as did data from the Northern Hemisphere.

Eulerian spectra of the v component over New Zealand agreed well with results from the Northern Hemisphere; spectral densities of the u component in the Southern Hemisphere,. however, were approximately half of those found in the Northern Hemisphere (Washington, D. C.); the v spectra showed a peak at 1/14 day. Spectrum slope5 of “−1” are indicated at higher frequencies. Eulerian cospectra permitted a preliminary estimate of meridional transports of zonal momentum.

A crude estimate of the relation between Eulerian and Lagrangian spectra yielded considerably different results for the Southern than for the Northern Hemisphere as did estimates of the coefficients of eddy diffusivity Kx and Ky.

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Gene L. Wooldridge and Ronan I. Ellis

Abstract

Criteria for stationarity of turbulent atmospheric flow are examined for the mesoscale in a mountain valley in northeastern Utah. Data from four sequences of superpressure balloon flights are used.

The study shows that the horizontal components of the Lagrangian velocities at levels below the ridges of the surrounding mountains are only weakly stationary; the vertical component fits the criteria better. Above the ridge levels all components of the velocities exhibit reasonable stationarity in the turbulent flow.

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