First Southern Hemisphere common‐volume measurements of PMC and PMSE

Abstract

[1] Using Rayleigh lidar and Mesosphere-StratosphereTroposphere 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.

Coincident measurements of PMSE and NLC above ALOMAR (69° N, 16° E) by radar and lidar from 1999–2008

“…This dataset, obtained at ALOMAR, was extended by von Zahn and Bremer (1999) presenting 22 cases and defining three types of layers, namely PMSE and NLC in a common volume, which accounted for 63% of all cases, layers with temporal differences (16%) and spatial differences (21%). PMSE and NLC have also been observed at other locations, among them Spitsbergen , Poker Flat, Alaska (Taylor et al, 2009) and Antarctica (Klekociuk et al, 2008). In all observations, a striking coincidence of lower boundaries of both PMSE and NLC layers were observed at times, but not always.…”

“…The coincidence of PMSE and NLC bottom altitudes was reported from different locations, first by von Zahn and Bremer (1999) at Andøya, later on by in Spitsbergen, Klekociuk et al (2008) in Antarctica and others. Having in mind that PMSE is sensitive to a wider spectrum of ice particle sizes, such a missing separation hints at a very rapid sublimation.…”

Wave influence on polar mesosphere summer echoes above Wasa: experimental and model studies

“…The 2-, 5-and 10-15-days planetary waves have been studied with PMSE measurements in a number of publications (Kirkwood and Réchou, 1998;Klekociuk et al, 2008;Morris et al, 2009). The quasi 2-day planetary wave is also a well known atmospheric periodic process in the upper atmosphere (Muller and Nelson, 1978;Rodgers and Prata, 1981;Salby, 1981;Pogoreltsev, 1999).…”

“…PMSE and NLC are wonderful natural laboratories for studying the highly dynamical regime of the summer mesopause, in which turbulent vortices as well as waves of different scales from a few km to several thousand km regularly occur (Kirkwood and Réchou, 1998;Dalin et al, 2004;Klekociuk et al, 2008;Morris et al, 2009;. PMSE are extensively exploited to verify the existing theories on the dusty plasma-neutral turbulent state of the mesosphere (Kelley et al, 1987;Cho and Röttger, 1997;Rapp and Lübken, 2003;Rapp et al, 2008;Varney et al, 2011).…”

Evidence of Polar Mesosphere Summer Echoes Observed by SuperDARN SANAE HF Radar in Antarctica

“…The few coherent VHF observations from the Antarctic indicate irregular PMSE distribution due to its complex mesospheric thermal phenomena. For instance, some studies have observed PMSE in the VHF band in correlation and anti-correlation to temperature, neutral winds, particle precipitation, cosmic noise absorption and gravity waves (Cho et al 1992;Kirkwood 1993;Röttger 1994;Hoffmann et al 1999;Klostermeyer 1999;Liu et al 2002;Klekociuk et al 2008). These complex phenomena range from periodic and episodic perturbations to those on a global scale.…”