Radiometric Estimation of Cloud Cover

Estimates of cloud cover based on all-sky temporal and spatial radiometric measurements of downward long-wave radiation are compared with visual estimates of the same cloud cover. A detailed comparison of the two estimates over a 5-week study period shows the radiometric method to be reliable. Examination of radiometric data taken over a period of 15 mo indicates that calibration parameters required for estimating cloud cover are not seasonally dependent. Details of the analysis technique are given along with indications for future development of meteorological instrumentation.