9:45 AM - 10:00 AM
[PEM27-07] Statistical study of probability of instabilities in the polar upper mesosphere/lower thermosphere
Keywords:polar upper mesosphere and lower thermosphere, convective instability, dynamical instability, sodium LIDAR, Tromsoe
Studies of probabilities of instabilities around the mesopause region were made at middle/low latitudes. Zhao et al. (JASTP, 65, 219-232, 2003) analyzed 32 nights (195 hours) of data sets over 1 year between June 1998 and May 1999 obtained at Starfire Optical Range, near Albuquerque, NM (35N, 106.5W) and showed that the probabilities of static and dynamic instabilities were maximum in mid-winter. Li et al. (JGR, 110, 2004JD005097, 2005) analyzed 19 nights of data sets obtained between January 2002 and November 2003 at Maui, Hawaii (20.7N, 156.3W), and pointed out that at any given time the probability that an unstable condition was found at some altitudes in the 85-100 km range was about 90%. To the best of our knowledge, no such a study has been made for the polar upper mesosphere/lower thermosphere.
We will show probabilities of instabilities in the polar upper mesosphere and lower thermosphere, and difference of the probabilities in terms of year, month, and altitude. Furthermore, we will discuss correlations between the probabilities and amplitudes of tides/gravity waves and between the probabilities and auroral activity.