Simultaneous observations of Polar Stratospheric Clouds and HNO3 over Scandinavia in January, 1992 by Massie, S, Dye, J, Baumgardner, D, Randel, W, Wu, F, Tie, X, Pan, L, Figarol, F, Brasseur, G, Santee, M, Read, W, Grainger, R, Lambert, A, Mergenthaler, J, Tabazadeh, A