Association of Antarctic polar stratospheric cloud formation on tropospheric cloud systems

The formation of polar stratospheric clouds (PSCs) is critical to the development of polar ozone loss. However, the mechanisms of PSC formation remain poorly understood, which affects ozone loss models. Here, based on observations by the NASA A-train satellites, we show that 66% ± 16% and 52% ± 17% of PSCs over west and east Antarctica during the period June-October 2006 were associated with deep tropospheric cloud systems, with maximum depths exceeding 7 km. The development of such deep tropospheric cloud systems should cool the lower stratosphere through adiabatic and radiative processes, favoring PSC development. These deep systems also transport lower tropospheric air into the upper troposphere and lower stratosphere. These new findings suggest that Antarctic PSC formation is closely connected to tropospheric meteorology and thus governed by synoptic scale dynamics, local topography, and large-scale circulation. More dedicated studies are still needed to better understand Antarctic PSC formation.