FIRST RESULTS OF HIGH RESOLUTION BALLOON-BORNE TURBULENCE MEASUREMENTS IN THE STRATOSPHERE

We have developed a compact balloon payload for wind turbulence soundings up to 35 km altitude. The wind measurements are performed with a hot wire anemometer (or constant temperature anemometer, CTA) and have a vertical resolution of 2.5 mm, which enables us to measure the turbulent spectrum down to the viscous sub-range. The balloon payload has been launched successfully several times since autumn 2007 from our site at Kuhlungsborn (54 degrees N, 12 degrees E), Germany. In October 2008 the sensor has been flown as part of the BEXUS 6 balloon payload from Kiruna (67 degrees N, 21 degrees E), Sweden. In the stratosphere our measurements show thin turbulent layers with a vertical extent of at most 200 m and sharp dividing boundaries. Due to the high measurement resolution it is possible to measure the turbulent spectrum in the stratosphere down to the viscous subrange. The power spectra within the turbulent layers correspond to the turbulent spectra expected from theory. By fitting a spectral model to our measured spectra we determine the inner scale and therewith the energy dissipation rate.