VARIABILITY OF THE UPPER TROPOSPHERE AND LOWER STRATOSPHERE OBSERVED WITH GPS RADIO OCCULTATION TEMPERATURES

TORSTEN SCHMIDT, PABLO LLAMEDO, ALEJANDRO DE LA TORRE, STEFAN HEISE, FLORIAN ZUS, GEORG BEYERLE, ANTONIA FABER, JENS WICKERT

Buenos Aires

Workshop; 7th IAGA / ICMA / CAWSES Workshop on Long-Term Changes and Trends in the Atmosphere; 2012

IAGA / ICMA / CAWSES

The radio occultation (RO) technique uses GPS signals received aboard low Earth orbiting satellites for atmospheric limb sounding. Temperature profiles are derived with high vertical resolution. Due to its long-term stability, all-weather capability and global coverage the GPS RO technique offers the possibility for global monitoring of the tropopause and temperature structure in the upper troposphere and lower stratosphere (UTLS) region. Each, the German CHAMP (2001-2008), the TerraSAR-X (since 2007), and the US/German GRACE (since 2006) missions provide between 150-200 occultation measurements daily. Based on these datasets a global increase of the tropopause height of about 7 m/year is detected since 2001. The tropopause rising is in agreement with a global upper tropospheric warming and a predominant lower stratospheric cooling observed for the same time interval. Regional trend patterns, mainly for the tropical tropopause region in relation to water vapor and ozone variability, are discussed.