Microphysical properties of continental clouds from in situ measurements

It is important to gain knowledge about the microphysical characteristics o f continental clouds in order to properly understand their formation, their radiative properties and their ability to produce precipitation. Satellite s to remotely sense cloud properties, and cloud interactions with aircraft that fly through them require knowledge of cloud microphysics. Moreover, nu merical simulations of global climate are sensitive to small systematic cha nges in cloud optical proper-ties, but very few large datasets are availabl e that document the characteristics of continental clouds. This paper summa rizes 9 X 10(4) km of in-cloud measurements made by the Central Aerological Observatory over the former USSR during 1977-84. Statistical characteristi cs of total water content (W), extinction coefficient (beta), effective dia meter (D-eff) and effective concentration (N-eff) are summarized as functio ns of temperature and cloud type, for measurements archived at 700 m horizo ntal resolution. The effect of threshold sensitivity, or cloud definition, on the statistical distributions is discussed. Decreases of W, and N-eff wi th colder temperatures are consistent with our general knowledge of cloud f ormation. For all temperature intervals and cloud types, correlations betwe en pairs of W, beta and D-eff are too small thereby barring any hope of sim ple linear parametrizations. Differences in W, beta, D-eff and N-eff for th e various cloud types indicate changes in cloud formation mechanisms. These data can assist in verification studies of cloud parametrization schemes i n general-circulation models, numerical weather-prediction models, and clou d-resolving models. The problems of cloud type, scale averaging, variabilit y over a model grid cell, distribution of water between the liquid and ice phase, and the lumping together of precipitating and non-precipitating clou ds must be considered in these studies.