Extended Abstract (192K)6.1
Properties of super-cooled water clouds over South Pole
Von P. Walden, Dept. of Geography, Univ. of Idaho, Moscow, ID; and M. E. Ellison, R. E. Brandt, M. S. Town, S. R. Hudson, and R. M. Jones
Super-cooled liquid water droplets exist in clouds over the Antarctic Plateau in summertime at temperatures well below freezing. Knowledge of both the macro-physical and micro-physical properties of such clouds is important because general circulation and weather prediction models are very sensitive to cloud properties. A hydrometeor videosonde (HYVIS) was operated in January 2001 as part of the South Pole Atmospheric Radiation and Cloud Lidar Experiment (SPARCLE). The HYVIS was flown aboard a tethered balloon into low-lying clouds over South Pole within about 1 km of the surface. Some of the clouds sampled during the austral summer are composed entirely of super-cooled water droplets at temperatures around -30 C. The HYVIS images of cloud droplets are converted to digital images, which allows individual water droplets to be sized using image-analysis techniques. Preliminary estimates of the radii of the droplets typically range from a few micrometers to about 20 micrometers with a mode of about 7 micrometers. On a few, rare occasions, some large droplets are observed with radii around 40 to 50 micrometers.
Session 6, The Polar Atmosphere - Clouds, Radiation, Aerosols
Tuesday, 11 January 2005, 3:30 PM-5:45 PM
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