Microphysical properties of Antarctic polar stratospheric clouds and their dependence on tropospheric cloud systems

Loknath Adhikari,Zhien Wang,Dong Liu

doi:10.1029/2009jd012125

Loknath Adhikari, Zhien Wang + Show 1 more

Open Access

https://doi.org/10.1029/2009jd012125

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Abstract

Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat satellite measurements are used to investigate the impact of tropospheric high and deep clouds on the microphysical properties of polar stratospheric clouds (PSCs) over Antarctica during the 2006 and 2007 winters. Based on the attenuated lidar scattering ratio and PSC depolarization ratio (δ′), PSCs are classified into supercooled ternary solution (STS), Mix 1, Mix 2, and ice classes with significantly different microphysical properties in terms of the PSC backscattering coefficient (β532) for 532 nm, the color ratio (β1064/β532), and δ′. In the early stages of the PSC season, STS accounts for more than 50% of the total PSCs, but the Mix 1, Mix 2, and ice classes become more common in the late season. During the late PSC season, close to 70% of PSCs are formed in association with high and deep tropospheric cloud systems, indicating the important role of tropospheric weather systems in Antarctic PSC formation. Tropospheric cloud systems also affect the microphysical properties of PSCs by affecting the relative occurrence of different PSC classes, especially during September and October. Our results also show that there are noticeable differences in color ratio and β532 (at the 0.05 significance level) for the ice class and Mix 2 (late season only) for PSCs associated and not associated with high and deep tropospheric cloud systems. These results indicate that the impact of tropospheric meteorology on PSC formation should be fully considered to better understand interannual variations and recovery of the Antarctic ozone hole.

Highlights

[1] Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat satellite measurements are used to investigate the impact of tropospheric high and deep clouds on the microphysical properties of polar stratospheric clouds (PSCs) over Antarctica during the 2006 and 2007 winters
Using the CALIPSO and CloudSat measurements, this study explores the effects of tropospheric cloud systems on the microphysical properties of PSCs
Since we are interested in a possible connection of PSC microphysical properties with tropospheric cloud systems rather than the horizontal coverage of PSCs, we did not make any adjustment for the latitudinal nonuniformity of the CALIPSO/CloudSat data and weighted all measurements

Summary

Introduction

[2] Polar Stratospheric Clouds (PSCs) are important to ozone‐depleting processes in the polar regions [Solomon, 1999; Tolbert and Toon, 2001; Rex et al, 2004; Douglass et al, 2006]. PSCs affect ozone depletion in two ways: (1) PSCs provide a surface for heterogeneous reactions that convert stable chlorine to highly reactive forms and nitrogen oxides to nitric acid [Strawa et al, 2002]. The. D00H18 different sensitivities of lidar and radar measurements to particle concentration and size distribution provide information for characterizing tropospheric cloud systems as well as PSCs. By combining other A‐train satellite measurements, we have unique data that may allow for a better understanding of PSCs. Teitelbaum et al [2001] used Polar Ozone and Aerosol Measurement (POAM II) and Television Infrared Observation Satellites (TIROS) Operational Vertical Sounders (TOVS) data and showed that PSCs and ozone minima over the Arctic are associated with anticyclonic potential vorticity anomalies near the tropopause, resulting in an upward displacement of isentropic surfaces.

Data Analysis

Evolution of PSCs During the Winters of 2006 and 2007

Conclusion