Lidar observations of sodium density depletions in the presence of polar mesospheric clouds

摘要: Abstract Since 1997, sodium resonance lidar and Rayleigh measurements have been conducted simultaneously at the Sondrestrom upper atmosphere research facility near Kangerlussuaq, Greenland (67.0°N, 309.1°E) for studying arctic mesosphere. The summertime observations during typical polar mesospheric cloud (PMC) season from June through August are used to investigate changes in layer related presence of PMCs. Our demonstrate, on average, a 20% reduction density below peak altitude when PMCs detected by lidar. Individual PMC events can produce appreciable depletions lower half layer. We observed nearly 50% column abundance 92 km with moderate backscatter strength. magnitude depletion is correlated New modeling results that include photolysis bicarbonate suggested may be associated adsorption atoms onto surface ice particles. not as significant iron South Pole austral summer months. This difference result fact resides few kilometers higher than layer, and, therefore, exposed presumably smaller particles (with less area) thus, has reduced uptake rate ice. extend previously reported reductions potassium sodium, support role heterogeneous chemistry new important process mesopause.