Investigations of stratospheric temperature regional variability with lidar and Advanced Microwave Sounding Unit

摘要

Seasonal and interannual stratospheric temperature variability at two relatively close-by lidar stations, the Observatoire de Haute-Provence (France) and the Hohenpeissenberg Observatory (Germany), are investigated using lidars and the Advanced Microwave Sounding Unit (AMSU) satellite data to examine possible causes of temperature trend discrepancies between these two sites. We first examined data measured by lidar and AMSU at each station and found that temperature anomalies observed with lidar have larger spread than those with AMSU probably as a result of distinct vertical sampling. Lidar and AMSU measurements have correlation typically higher than 0.7; however, correlation is decreased to 0.4-0.5 in summer at the French station. Lidar measurements have good correlation between the two stations, around 0.9 in winter and 0.45 in summer, while AMSU data show correlations between both stations of about 0.94 year-round. Data from coincident measurement dates at both sites have then been taken from the integral series in order to isolate local geophysical effects. A comparison between lidar and AMSU measurements of coincident dates suggests that in wintertime measurement discrepancies are to a great extent a result of different local atmospheric dynamics. These are important on the estimation of stratospheric trends and can partially explain discrepancies observed in trends estimates based on lidars in distinct locations or on satellite data. The present results have implications on the planning of measurement strategies using lidars involved in the Network for the Detection of Atmospheric Composition Changes (NDACC), as well as on methodologies for satellite data use for stratospheric monitoring purposes.