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Uwe Radok

A representative picture, from the aeronautical point of view, of vertical currents above mountainous country is obtained by letting these currents act on an aircraft set to fly horizontally in still air. Pressure and temperature traces recorded by such an aircraft give the effective vertical velocities and some idea of the temperature lapse rate in the undisturbed stream. Two sets of results are given for illustration. One shows low-level lee waves which were caused presumably by a temperature inversion; the other is a case of strong turbulence side by side with a smooth wave, in which downdrafts reached 1600 ft/min in an 18-knot wind.

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Uwe Radok
and
Alison M. Grant

Abstract

As first step in an investigation of changes in the high-level circulation of the southern hemisphere, more than 18,000 radiosonde flights have been used to construct a three-year series of monthly mean cross-sections for the eastern Australian sector and to draw, with their help, monthly mean 200-millibar charts for the entire region of Australia and New Zealand, by methods suited to its sparse upper-air station network. For eleven of the 36 months, the cross sections could be extended as far as the Antarctic coast to show details of a high-latitude jet stream. The 200-mb charts reveal distinct deviations from zonal flow, but only a few of these seem clearly linked to certain seasons or regions. Transitions from summer to winter flow-patterns occurred as a rule abruptly, and on several occasions coincided with the opposite transition in the zonal mean flow of the northern hemisphere.

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