MULTI-INSTRUMENT ZENITH OBSERVATIONS OF NOCTILUCENT CLOUDS OVER GREENLAND ON JULY 30 31, 1995/

Results are presented for zenith observations of a noctilucent cloud ( NLC) display over the Sondrestrom atmospheric research facility near K angerlussuaq, Greenland, on July 30/31, 1995. The observations were ma de with a Rayleigh lidar, which measured the NLC particle volume backs catter coefficient, and with a UV spectrograph, which measured the int ensity and degree of linear polarization of solar light scattered from the NLC. The intensity and polarization measurements were made at sol ar depression angles of -1.8 degrees to -4.6 degrees. These data allow ed the first simultaneous observation from the ground of the altitude and thickness of the NLC and of the radius of the NLC particles. The N LC was found to be between 86 and 84 km in altitude with a thickness o f 1 to 2 km and the NLC particles had a radius at or below 0.07 mu m. We also report the first observation of an NLC sublimating due to the passage of an AGW through the 85-km altitude region. These observation s are generally in agreement with models of noctilucent clouds.