@article{oai:nipr.repo.nii.ac.jp:00001500, author = {Kawaguchi, Sadao}, journal = {Memoirs of National Institute of Polar Research. Special issue}, month = {Nov}, note = {P(論文), This paper presents the infrared effective emissivity value of low and middle clouds deduced from 26 radiometersonde ascents carried out during 1967-1969,at Syowa Station, East Antarctica. The average cloud emissivities were 0.83 for the downward and 0.69 for the upward flux. The discrepancy was mainly due to the difference of the spectral distribution of both fluxes, as the downward flux over cloud top is very small in comparison with the equivalent black body radiation due to the scarcity of water vapor in the upper atmosphere in Antarctica. In this study, the effective emissivity was dominated more by the radiation field of the cloud circumference than by the radiative property of cloud itself. The emissivity increased with increasing cloud thickness till 800-1000m, and thereafter had a high constant value about 0.95 for the downward flux. The emissivity showed a decreasing tendency with increasing cloud base height. The IR radiative cooling of cloud is very notable; cooling rate of some 10 degrees centigrade per day was found in the upper part of cloud, and some zero cooling rate or heating was found in the lower part.}, pages = {70--76}, title = {Effective infrared emissivity of clouds in Antarctica}, volume = {29}, year = {1983} }