Borsche, M., Kirchengast, G., Foelsche, U., Gobiet, A., Steiner, A. K., Schmidt, T., Wickert, J. (2006): Tropical tropopause variability from four years of CHAMP radio occultation data, (Geophysical Research Abstracts, Vol. 8, 09592, 2006), 3rd General Assembly European Geosciences Union (Vienna, Austria 2006).