An updated assessment of stratospheric temperature trends (Invited Speaker)

An ongoing project under the WCRP SPARC program involves an updated analysis of stratospheric temperature trends. This talk will present a summary of temperature variability and trends in the stratosphere through 2005, including results from radiosondes, satellites and lidar data sets. After excluding radiosonde stations with apparent spurious cooling biases, temperature changes in the lower stratosphere are in good agreement between satellite and radiosonde data, showing cooling of ~0.5 K over much of the globe for 1979-2005. Substantially larger trends are observed in polar regions, especially during spring. Trends in the middle and upper stratosphere have been derived from updated Stratospheric Sounding Unit (SSU) data, showing unexpectedly weak trends in the middle stratosphere (30 km), and large cooling near the stratopause (~1.5 K/decade near 50 km). However, the effects of CO2 changes on the SSU observations may substantially influence the derived trends.