Document Type


Journal/Book Title/Conference

IAMAS Workshop on “Layered Phenomena in the Mesopause Region”

Publication Date



The Atmospheric Lidar Observatory (ALO) Rayleigh-scatter lidar has been operated for 11 years on the Utah State University (USU) campus (41.7o N 111.8o W). During the morning of 22 June 1995 a noctilucent cloud (NLC) was observed with the lidar well away from the twilight periods when NLCs are visible. It lasted for approximately one hour. This observation and a second in 1999 [Wickwar et al., 2002] are very significant because they show the penetration of NLCs equatorward of 50°, which may have important implications for global change. Temperature profiles calculated at hourly intervals were at least 20 K cooler than the 11-year June climatological average for ALO near the NLC altitude. These cool temperatures arose, in part, because of a major temperature oscillation.


Invited poster presented at IAMAS Workshop on “Layered Phenomena in the Mesopause Region”, Cambridge, UK, September 14–17, 2004. PDF of poster is available for download from link above.