Radiometric Measurements of In-Cloud Temperature Fluctuations

Abstract

The feasibility of measuring in-cloud temperature fluctuations with an infrared radiometer is demonstrated. The results obtained from aircraft measurements in a stratocumulus cloud deck indicate that a radiometer may easily resolve temperature variations within the cloud of less than 0.05°C provided that the cloud is sufficiently opaque. These radiometer measurements of temperature are combined with aircraft observations of vertical velocity to calculate a heat flux within the cloud deck. The heat flux derived using the radiometric observations shows excellent agreement with theoretical predictions of in-cloud heat flux. A similar heat flux calculation using the more conventional temperature transducer data was less by a factor of 5.