A statistical study of convective and dynamic instabilities in the polar upper mesosphere above Tromsø oleh Satonori Nozawa, Norihito Saito, Takuya Kawahara, Satoshi Wada, Takuo T. Tsuda, Sakiho Maeda, Toru Takahashi, Hitoshi Fujiwara, Viswanathan Lakshmi Narayanan, Tetsuya Kawabata, Magnar G. Johnsen