One year of cloud lidar data from Dumont d'Urville (Antarctica): 1. General overview of geometrical and optical properties

Authors

  • Massimo Del Guasta,

  • Marco Morandi,

  • Leopoldo Stefanutti,

  • Jacques Brechet,

  • Jacques Piquad


Abstract

Tropospheric clouds play a major role in climate regulation but, so far, only a few long-term ground-based observations, devoted to the study of the cloud optical and radiative properties, have been carried out. In this work the statistics of 1 year of coastal Antarctic cloud lidar measurements (532 nm) are shown. Cloud macrophysical and optical parameters have been retrieved from lidar returns; radiosonde data allowed us to build statistics of such quantities in terms of cloud temperature. Information about the physical phase of water and ice crystal habit has been obtained from the depolarization and extinction backscattering ratio; a change in crystal habit (and/or size) around −30°C is evidenced by the depolarization versus temperature behavior. The extinction/backscattering ratio shows a negative trend with temperature, reflecting microphysical changes. Visible extinction shows wide data dispersion, but with a marked negative trend with temperature. The relative derivatives of extinction and optical depth with temperature have been computed, such quantities result quite constant with temperature.

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