First detection of a noctilucent cloud by lidar

Abstract

During the night of August 5/6, 1989 for the first time a noctilucent cloud (NLC) was detected and measured by a lidar instrument. The observations were made with our ground‐based narrow‐band Na lidar located at Andenes, Norway (69°N, 16°E geographic coordinates). In wavelength the lidar was operated both at the Na D2 resonance line of 589 nm as well as 5 Doppler widths shifted away. The altitude resolution was 200 m. The NLC developed at about 22:20 UT, reached its maximum backscatter cross section at 23:05 UT and became unobservable at around 00:10 UT. During this period the NLC exhibited the following properties: (a) its altitude ranged between 83.4 and 82.2 km; (b) its full width at half maximum ranged between 1.4 and 0.3 km; (c) the ratio of measured backscatter intensity from the NLC to the calculated Rayleigh signal from 82.6 km reached 450; (d) its volume backscatter cross section maximized at 6.5·10−9 m−1 sr−1. Copyright 1989 by the American Geophysical Union.