Temperatures and winds during NLC and MSE


Noctilucent clouds (NLC) and mesospheric summer echoes (MSE) are mainly observed at high latitudes poleward of 60° latitude. Occasionally they also extend to mid-latitudes. Kühlungsborn (54°N) is located at the southern edge of the region where mesospheric temperatures are at least sometimes low enough for the existence of ice particles. But the NLC and MSE occurrence rates are much smaller than e.g. at the polar latitude of the ALOMAR observatory.
A closer look on the Kühlungsborn temperature data reveals that the mean temperature runs below the frost point temperature only above 85 km altitude. At typical NLC altitudes around 83 km the mean temperature is always above the frost point, despite noctilucent clouds are occasionally observed by lidar. We examined which local conditions (temperatures and winds) are connected with the observation of NLC. This gets important e.g. if studies on trends in NLC occurrence rates use visual observations from mid-latitudes up to 60°. (A quantitative description of the relation of (polar) NLC occurrence and the solar cycle is given here.) If conclusions from NLC occurrence on temperature trends shall be drawn, the relation between temperature and noctilucent clouds has to be known in detail.
At Kühlungsborn the lidar observations of NLC and temperatures are combined with radar soundings of MSE and horizontal winds. This combination of ground-based techniques enables detailed studies on ice, temperature, and winds with a better time resolution than in-situ soundings and a better spatio-temporal resolution than space-based techniques.