Polar stratospheric clouds over Antarctica from the CALIPSO spaceborne lidar

Vincent Noel (1, 2) , Albert Hertzog (1, 2) , Hélène Chepfer (1, 2) , David M. Winker (3)

1 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
2 IPSL - Institut Pierre-Simon-Laplace
3 LaRC - NASA Langley Research Center [Hampton]

This paper presents statistics of polar stratospheric clouds (PSCs) above Antarctica from June to October 2006 using observations from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) spaceborne lidar, part of the CALIPSO mission. Synoptic-scale changes in geographic and temporal distribution are documented weekly and correlated with temperature fields. A high spatial and temporal variability tends to contradict the hypothesis that PSCs are mostly created via slow processes mainly governed by large-scale temperature changes. Linear depolarization ratios reveal strongly typed PSCs with distinct characteristics (implying different microphysics), but unique cloud compositions cannot be singled out. A west/east imbalance is observed in the depolarization distribution, symptomatic of microphysical disparities. A classification based on depolarization and scattering ratios suggests more than 60% of mixed PSCs, followed by more than 20% of STS, and a roughly equal concentration of nitric acid trihydrate (NAT)-based and pure ice PSCs (∼8%). Up to the beginning of August, supercooled ternary solution (STS) PSCs experience a steady decrease in concentration correlated with an increase in ice-based and mixed PSCs; this tendency gets reversed after the first week of August, hinting at the existence of a large-scale seasonal cycle in PSC population.

Mots clés: PSC; lidar; CALIOP; microphysics

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]

Vincent Noel, Albert Hertzog, Hélène Chepfer, David M. Winker. Polar stratospheric clouds over Antarctica from the CALIPSO spaceborne lidar. Journal of Geophysical Research: Atmospheres, 2008, 113, pp.D02205. ⟨10.1029/2007JD008616⟩. ⟨hal-00260716⟩