Quasi-coincident observations of polar stratospheric clouds by ground-based lidar and CALIOP at Concordia (Dome C, Antarctica) from 2014 to 2018

Polar stratospheric clouds (PSCs) have been observed
from 2014 to 2018 from the lidar observatory at the
Antarctic Concordia station (Dome C), included as a primary
station in the NDACC (Network for Detection of Atmospheric
Climate Change). Many of these measurements
have been performed in coincidence with overpasses of the
satellite-borne CALIOP (Cloud Aerosol Lidar with Orthogonal
Polarization) lidar, in order to perform a comparison in
terms of PSC detection and composition classification. Good
agreement has been obtained, despite intrinsic differences in
observation geometry and data sampling. This study reports,
to our knowledge, the most extensive comparison of PSC observations
by ground-based and satellite-borne lidars.
The PSCs observed by the ground-based lidar and
CALIOP form a complementary and congruent dataset and
allow us to study the seasonal and interannual variations in
PSC occurrences at Dome C. Moreover, a strong correlation
with the formation temperature of NAT (nitric acid trihydrate),
TNAT, calculated from local temperature, pressure,
and H2O and HNO3 concentrations is shown. PSCs appear
at Dome C at the beginning of June up to 26 km and start to
disappear in the second half of August, when the local temperatures
start to rise above TNAT. Rare PSC observations in
September coincide with colder air masses below 18 km.