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American Meteorological Society, Journal of the Atmospheric Sciences, 14(56), p. 2345-2358, 1999

DOI: 10.1175/1520-0469(1999)056<2345:cscacs>2.0.co;2

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Continental Stratus Clouds: A Case Study Using Coordinated Remote Sensing and Aircraft Measurements

This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

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Data provided by SHERPA/RoMEO

Abstract

A continental stratus cloud layer was studied by advanced ground-based remote sensing instruments and aircraft probes on 30 April 1994 from the Cloud and Radiation Testbed site in north-central Oklahoma. The boundary layer structure clearly resembled that of a cloud-topped mixed layer, and the cloud content is shown to be near adiabatic up to the cloud-top entrainment zone. A cloud retrieval algorithm using the radar reflectivity and cloud droplet concentration (either measured in situ or deduced using dual-channel microwave radiometer data) is applied to construct uniquely high-resolution cross sections of liquid water content and mean droplet radius. The combined evidence indicates that the 350-600 m deep, slightly supercooled (2.0° to 2.0°C) cloud, which failed to produce any detectable ice or drizzle particles, contained an average droplet concentration of 347 cm3, and a maximum liquid water content of 0.8 g m3 and mean droplet radius of 9 m near cloud top. Lidar data indicate that the Ka-band radar usually detected the cloud-base height to within 50 m, such that the radar insensitivity to small cloud droplets had a small impact on the findings. Radar-derived liquid water paths ranged from 71 to 259 g m2 as the stratus deck varied, which is in excellent agreement with dual-channel microwave radiometer data, but 20% higher than that measured in situ. This difference appears to be due to the undersampling of the few largest cloud droplets by the aircraft probes. This combination of approaches yields a unique image of the content of a continental stratus cloud, as well as illustrating the utility of modern remote sensing systems for probing nonprecipitating water clouds.