Radiation Profiles in Extended Water Clouds. III: Observations

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  • 1 CSIRO Division of Atmospheric Physics, Aspendale, Victoria, Australia
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Abstract

Six case studies of “uniform” planetary boundary layer clouds are reported where the solar and infrared radiation fields, liquid water content, drop-size distributions and temperature and humidity profiles were measured simultaneously. The measurements are compared with theoretical prediction from a detailed radiative transfer model in an attempt to verify the performance of the model and its associated parameterization schemes (Parts 1 and 2). The measurements support the parameterization of both shortwave and longwave radiative characteristics in terms of vertical liquid water path (LWP) i.e., without the need to define cloud drop-size distributions. Within experimental error, there are no significant discrepancies between theory and measurement. However, there is some evidence in the present study, supported by measurements of others in (generally) thicker and denser clouds that solar absorption is in excess of theoretical prediction.

Abstract

Six case studies of “uniform” planetary boundary layer clouds are reported where the solar and infrared radiation fields, liquid water content, drop-size distributions and temperature and humidity profiles were measured simultaneously. The measurements are compared with theoretical prediction from a detailed radiative transfer model in an attempt to verify the performance of the model and its associated parameterization schemes (Parts 1 and 2). The measurements support the parameterization of both shortwave and longwave radiative characteristics in terms of vertical liquid water path (LWP) i.e., without the need to define cloud drop-size distributions. Within experimental error, there are no significant discrepancies between theory and measurement. However, there is some evidence in the present study, supported by measurements of others in (generally) thicker and denser clouds that solar absorption is in excess of theoretical prediction.

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