A Refined System for Pibal Theodolite Observations

To obtain more reliable mean wind profiles in the Ekman layer of the atmosphere, a system of two precision pilot-balloon theodolites is used. The system uses continous digital recording from optical shaft encorders on portable stereo tape recorders. Resolution is 0.01°. Simultaneous reading is secured by radio-link triggering of the quartz-controlled internal working frequency. The advantages in using this system are more accurate information at greater heights and an increased number of ascents providing a more statistically meaningful mean profile.