Ionospheric winds over Yuma, Arizona, measured by gun-launched projectiles

Abstract

The newly installed 420‐mm smoothbore gun at Yuma Proving Ground, Arizona, is described with its associated ground instrumentation. With an improved ignition system, this gun has placed an 84‐kg projectile at an altitude of 180 km. Twenty‐four of these projectiles carrying liquid trimethyl aluminum have been used to measure ionospheric winds through the creation of luminous trails. Analysis of these trails shows the presence of quite large easterlies at 110 km and a general descent of the wind patterns through the night. Harmonic analysis of the wind components at fixed altitude shows periodic components that are 2–5 times larger than the mean components and predominate periods of 10–12 hours. Seventy‐five per cent of the trails showed a characteristic clockwise rotation of the velocity vector. The absence of these phenomena at Barbados and the observation of counterclockwise rotation of trails over Argentina show the need for a theory to explain this behavior and its dependence on latitude and the earth's rotation.

Rotation of wind direction with altitude as obtained from vapor-trail observations

“…Wavelengths of 24 km near 90 km, increasing with altitude to 40 km above 120 km, are in excellent agreement with those reported by Murphy and Bull [1968] for Yuma. They are considerably larger, particularly at lower altitudes, than those found by Kochanski [ 1964], which varied from about 12 km below 100 km to 16 km at 120 kin, 28-30 km at 130 kin, and an occasional 40-50 km above 140 km.…”

“…Except for the upper part of the first (1954 HST) and the last (0225 HST) observations, a pronounced rotation with height is observable in these hodographs. Similar rotation has been reported by many investigators, although rotation is not observed in all trails, and, where it is noted, it is not always clockwise [Rosenberg and Edwards, 1964;Kochanski, 1964;Murphy, 1969;Bedinger et al, 1968;Murphy and Bull, 1968]. A study of 18 Kauai experiments conducted in May and June showed 12 experiments with clockwise rotation over a height interval of at least 20 km between 90 and 120 km.…”

“…A 20-km wavelength at lowest altitudes is twice the wavelength found by Rosenb•zrg and Edwards [!964] at 100 km, but a 40-km wavelength is in agree-ment with their estimate for 125 kin. Findings by Rosenberg and Edwards and Kochanski agree with the 20-and 45-km wavelengths assumed by Rosenberg [1968] in his rotating ionospheric wind model, with which he was able to derive excellent agreement between data and theory in a number of parameters.…”

“…One observation on October 12, 1962, showed consistent counterclockwise turning from 105 to 150 km [Smith, 1971]. Murphy and Bull [1968] It should be mentioned that on these trails, which extended upward from about 80 km to apogee near 160-170 km, the data resolution decreased with altitude. This decrease was a consequence of a more rapid change in trail dimensions caused by the increase of diffusion with height and by the rocket's moving progressively more horizontally near apogee while maintaining a nearly constant efflux of the effluent.…”

Winds and shears in the mesosphere and lower thermosphere: Results from four decades of chemical release wind measurements

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