Clouds in the Vicinity of the Stratopause Observed with Lidars at
Mid-latitudes (40.5-41°N) in China
Abstract
A cloud event in the altitude range of 53-65 km was observed with lidars
over Yanqing (40.5°N, 116°E) and Pingquan (41°N, 118.7°E) on 30 October
2018. Clouds with a multilayer structure first occurred within the line
view of lidar at dawn (03:40-06:00LT). They were faint and tenuous, and
the maximum volume backscatter coefficient (VBSC) was
1.4×10-10m-1sr-1.
At twilight, clouds with multilayer structures were reobserved via
lidars, but they became much thicker, with a maximum VBSC of
11.2×10-10m-1sr-1.
The structure of the cloud layers varied with time, and they faded
completely at approximately ~00:30 LT (+1 day).
Measurements from SABER/TIMED were utilized for analysis, and it was
found that before the onset of cloud event, a temperature anomaly
occurred in the mesosphere over Beijing, and water vapor was also very
abundant. The frost point temperature profile of water vapor was
estimated, and lidar measurements showed that the atmospheric
temperature was close to the frost point of water vapor in the vicinity
of the stratopause when the mesosphere was undergoing a low-temperature
phase. It was a rare mesospheric cloud event observed with lidars at
rather low latitudes, and the clouds probably resulted from the
nucleation of saturated water vapor due to the occurrence of a
temperature anomaly in the mesosphere.