First lidar observations of mesospheric hydroxyl

Abstract. Ground-based lidars have been used to detect and identify ground-state (v"=0) hydroxyl radicals (OH) in the mesosphere between about 75 and 85 km altitude. These lidars operate near 308 nm and OH is observed through laser-induced-fluorescence on the A2+ − X2(0; 0) band. The results expose a valuable global set of nighttime OH observations, since existing long-term lidar data at sev-eral NDSC sites contain the (serendipitous) OH informa-tion. Results of lidar observations are presented from two mid-latitude sites, one in each hemisphere: Table Mountai