Overview of and first observations from the TILDAE High-Altitude Balloon Mission

Abstract

Abstract. Though the presence of intermittent turbulence in the stratosphere has been well established, much remains unknown about it. In situ observations of this phenomenon, which have provided the greatest details of it, have mostly been achieved via sounding balloons (i.e., small balloons which burst at peak altitude) carrying constanttemperature "hot-wire" anemometers (CTAs). The Turbulence and Intermittency Long-Duration Atmospheric Experiment (TILDAE) was developed to test a new paradigm for stratospheric observations. Rather than flying on a sounding balloon, TILDAE was incorporated as an "add-on" experiment to the payload of a NASA long-duration balloon mission that launched in January 2016 from McMurdo Station, Antarctica. Furthermore, TILDAE's key instrument was a sonic anemometer, which (relative to a CTA) provides bettercalibrated measurements of wind velocity and a more robust separation of velocity components. During the balloon's ascent, TILDAE's sonic anemometer provided atmospheric measurements up to an altitude of about 18 km, beyond which the ambient air pressure was too low for the instrument to function properly. Efforts are currently underway to scientifically analyze these observations of small-scale fluctuations in the troposphere, tropopause, and stratosphere and to develop strategies for increasing the maximum operating altitude of the sonic anemometer.

On the use of cup anemometers as wind speed sensors in stratospheric balloon missions

“…For the wind speed measurement in low density environments, the literature shows a lack of research. Sonic anemometers have been tested by Maruca et al, which show this type of instrument can make measures to a top altitude of 17 km, with poor measurements above 18 km [6]. However, stratospheric balloons can reach higher altitudes (18-37 km commonly), which makes the sonic anemometer not-at-all ideal for the expected floating altitudes of the mission and for part of the ascent phases.…”

Measuring Relative Wind Speeds in Stratospheric Balloons with Cup Anemometers: The TASEC-Lab Mission

“…Maruca et al developed a very interesting experiment on the use of sonic anemometers at high altitudes [ 19 ]. They compared their data with two radiosondes launched the same day, and the results obtained from the sonic anemometer and the radiosondes seemed to be well correlated.…”