Gravity-wave influences on Arctic mesospheric clouds as determined by a Rayleigh lidar at Sondrestrom, Greenland

Since 1994, Rayleigh lidar measurements of the Arctic middle atmosphere have been conducted at the Sondrestrom research facility near Kangerlussuaq, Greenland (67.0N,50.9W). The summer lidar observations typically cover the late June through August period. From these observations, 220 hours of noctilucent clouds (NLCs) have been detected by the lidar spanning 16 hours of local time. Organizing the cloud characteristics irrespective of local time reveals the most common cloud height as 82.5 km, the most common full-width-half-maximum (FWHM) as 0.7 km, and the most common peak volume backscatter coefficient as 20.0 x 10^-11 m^-1 sr^-1. The FWHM is noticeably thinner than determined by other lidar observations of NLCs in Norway and the South Pole. We found the mean backscatter strength to increase and the FWHM to decrease with decreasing cloud height. In addition, the cloud slopes with time are greater for the thicker weaker clouds at higher altitudes than the thinner stronger clouds at lower altitudes. Gravity-wave signatures are routinely observed in the cloud detections. Upon estimating stratospheric wave activity in the data, we observed stronger cloud backscatter during low gravity-wave activity and weak cloud backscatter during high gravity-wave activity. To help support these results, simulations from a microphysical cloud model were performed under summer mesospheric conditions with and without gravity-wave activity. Upon including short-period (∼2-3 hours) gravity-wave activity, the model simulation reproduced the behavior observed in the ensemble cloud properties by producing a broader altitude distribution, weaker backscatter strength, and thinner clouds.