Remote Sounding of High Clouds: II. Emissivity of Cirrostratus

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

The results from a series of measurements of the beam emissivity of cirrostratus at 10–12 μm wavelengths are presented, using methods of analysis which were discussed in Part I. A ruby lidar and infrared radiometer were used to gather data remotely from the ground. The various sources and magnitudes of error are discussed. The results for eight large cirrostratus systems which were observed on different days gave a mean beam emissivity of 0.54 (or flux emissivity of 0.70). This compares with a value of 0.245 (0.38 for flux obtained during an earlier period (Platt, 1973). The measurements were obtained at 35°S (Adelaide) and 38°S (Aspendale). The cloud systems at Aspendale all formed in similar synoptic situations.

Abstract

The results from a series of measurements of the beam emissivity of cirrostratus at 10–12 μm wavelengths are presented, using methods of analysis which were discussed in Part I. A ruby lidar and infrared radiometer were used to gather data remotely from the ground. The various sources and magnitudes of error are discussed. The results for eight large cirrostratus systems which were observed on different days gave a mean beam emissivity of 0.54 (or flux emissivity of 0.70). This compares with a value of 0.245 (0.38 for flux obtained during an earlier period (Platt, 1973). The measurements were obtained at 35°S (Adelaide) and 38°S (Aspendale). The cloud systems at Aspendale all formed in similar synoptic situations.

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