Temperature, humidity, and wind at the global tropopause

This study presents global statistics of tropopause parameters for a 15-yr period (1979-93). The parameters are height, temperature, potential tempera ture, mixing ratio of water vapor, and zonal, meridional and vertical wind. The global tropopause is derived from ECMWF reanalysis data by applying th e thermal and dynamical definitions of the tropopause. The tropopause clima tology evaluated from the ECMWF reanalysis data is compared with those prov ided by radiosonde and satellite data. The meridional and zonal variations in the mean tropopause height and temperature reflect the global jet stream structure. The seasonal variation of tropical trepopause temperatures is c haracterized by a minimum during Northern Hemispheric summer and a correspo nding winter maximum. The tropopause mixing ratio of water vapor attains a minimum in the Tropics that increases gradually poleward. The maximum of th e relative humidity occurs in the Tropics above the Pacific and Indian Ocea ns. There are no global trends in the height and temperature of the tropopa use but a decrease of about 10% per decade is evaluated for the mixing rati o of water vapor. The negative trend is particularly strong above both pola r regions.