Measurements from a zero-pressure balloon in the stratopause (48 km)

Abstract

The results of an experiment conducted at White Sands Missile Range, New Mexico, on September 11, 1968, in which a very large zero‐pressure balloon served as a platform for instruments measuring pressure and temperature, are discussed. The results of an analysis for diurnal tidal motion of wind as determined from the balloon trajectory are also included. The balloon remained in the stratopause region (48.75–47.80 km) for about four hours, during which time its trajectory with respect to altitude exhibited significant wave like structure. During the four‐hour period an average temperature of +2°C was computed from the slope of a least‐squares fit straight line of ln p (measured pressure values) versus altitude. A corresponding temperature value of −2°C was obtained from averaging the adjusted temperatures measured with the balloon‐borne instruments. Additionally a rocketsonde launched during the time the balloon was in the stratopause region recorded a temperature of 0°C at 48 km. There was excellent agreement (within 3%) between pressures computed from the rocket sounding and those measured with balloon‐borne instruments. A large horizontal change in temperature (23°C in 31 km) was measured at the stratopause level. Through calculations of atmospheric density based on measurements of pressure and temperature, it was concluded that vertical air motion was largely responsible for the wavelike trajectory. An estimate over one ten‐minute period placed the upward air velocity at greater than 70 cm sec−1. Wind analysis with respect to the diurnal tidal components produced results that are in general agreement with conclusions based on previous rocket experiments.