First Southern Hemisphere common‐volume measurements of PMC and PMSE

Using Rayleigh lidar and Mesosphere‐Stratosphere‐Troposphere radar at Davis Antarctica (68.6°S) during the 2005–2006 austral summer, we obtained the first Southern Hemisphere common‐volume measurements of Polar Mesospheric Clouds (PMC) and Polar Mesosphere Summer Echoes (PMSE). PMC were observed with 6% probability during 349 hours of lidar observations. PMSE were simultaneously observed during 70% of the PMC events. The mean centroid altitudes of simultaneous PMC and PMSE were 83.97 ± 0.10 km and 85.31 ± 0.14 km, respectively. The altitude difference (∼1.3 km) is comparable to earlier boreal common‐volume measurements. Both phenomena show clear diurnal variations in altitude and occurrence. PMC had a unimodal local time occurrence distribution which peaked 4–6 hours after solar midnight. PMSE were most prevalent at this time, but had a secondary occurrence peak ∼6 hours after solar noon when PMC were absent. We explain the altitude‐time distributions of PMC and PMSE in terms of the thermal structure of the mesopause region determined using measurements from the Aura satellite.