Simultaneous observation of sodium atoms, NLC and PMSE in the summer mesopause region above ALOMAR, Norway (69°N, 12°E)

Based on simultaneous observations of Na density, polar mesosphere summer echoes (PMSE) and noctilucent cloud (NLC) at ALOMAR, Norway (69 degrees N) during the summers of 2001 and 2002, we report the strong anti-correlation of sodium atoms with NLC, suggesting that in the presence of large ice particles Na is always absent, and a weaker anticorrelation of sodium atoms with PMSE, suggesting that a population of sub-visible particles also deplete Na to a varied degree. This conclusion is in general agreement with recent reports on iron and potassium atom-ice particle anticorrelation. For this study, we use data taken with the Weber Na lidar, the ALWIN VHF radar, and the RMR lidar on 8 specific days in 2001 and 4 days in 2002 plus half-monthly average variation over the summer 2001 based on all 17 days of coincident measurements. (c) 2005 Elsevier Ltd. All rights reserved.