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AGU: Geophysical Research Letters

 

Index Terms

  • Atmospheric Composition and Structure: Cloud physics and chemistry
  • Meteorology and Atmospheric Dynamics: Climatology
  • Meteorology and Atmospheric Dynamics: Remote sensing
  • Meteorology and Atmospheric Dynamics: Theoretical modeling

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 29, 1338, 4 PP., 2002
doi:10.1029/2002GL014828

Analysis of lidar measurements of ice clouds at multiple incidence angles

Vincent Noel

Laboratoire de Météorologie Dynamique, Ecole Polytechnique, Palaiseau, France

Gilles Roy

Defence Research Establishment Valcartier, Val-Belair, Quebec, Canada

Luc Bissonnette

Defence Research Establishment Valcartier, Val-Belair, Quebec, Canada

Hélène Chepfer

Laboratoire de Météorologie Dynamique, Ecole Polytechnique, Palaiseau, France

Pierre Flamant

Laboratoire de Météorologie Dynamique, Ecole Polytechnique, Palaiseau, France

The focus of this paper is the retrieval of the oscillation angle of crystals around the horizontal plane, in low-level ice clouds, using the lidar depolarization ratio. An ice cloud located between 0.5 and 2.25 km of altitude has been studied. Measurements were taken near Montreal, on February 2nd, 2000, with a 1.06-μm lidar with scanning capability and dual polarization. The scanning observations show high variations of both backscattering coefficient and depolarization ratio, that are usually associated with horizontally-oriented crystals. A technique has been developed to retrieve the average crystals oscillation angle: the evolution of the measured lidar depolarization ratio with the lidar beam incidence angle on the cloud is compared with simulations of lidar depolarization ratio computed through ray-tracing. For the fore mentioned case, the average crystal oscillation angle is estimated to be 12° and the relative quantity of oriented ice crystals in the cloud to be 20%.

Published 14 May 2002.

Citation: Noel, V., G. Roy, L. Bissonnette, H. Chepfer, and P. Flamant (2002), Analysis of lidar measurements of ice clouds at multiple incidence angles, Geophys. Res. Lett., 29(9), 1338, doi:10.1029/2002GL014828.

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