Global tropopause height trends estimated from GPS radio occultation data

This study discusses global tropopause height variabilities and trends based on zonal monthly mean GPS radio occultation data from the German CHAMP satellite mission for the period May 2001-December 2007 (80 months). A data gap of missing CHAMP data in July 2006 was filled with radio occultation data of the US-German GRACE mission. A global increase of the tropopause height between 26-44 m during the observation period (4-7 m/yr) is found depending on the binning method (5 degrees or 10 degrees latitude bands) and the used tropopause detection algorithm. The corresponding trend errors vary between 19-21 m. The inclusion of the quasi-biennial oscillation in the regression model leads to a global increase of the tropopause height from 1-5 m (2-12%) during the time period depending on the binning method. Global tropopause height variations are positively correlated with upper tropospheric (500-100 hPa) and anti-correlated with lower stratospheric (100-30 hPa) temperature variations.