Keywords: spectral model, cloud microphysics, bulk parameterization of cloud and precipitation formation, autoconversion, accretion, sedimentation, coagulation

Several series of numerical experiments were conducted using the one-dimensional spectral microphysical cloud model developed at UkrHMI for marine stratiform-convective clouds of the surface layer and diagrams were constructed to determine the coefficients of coagulation of cloud droplets and precipitation drops. The rates of autoconversions, accretion, and sedimentation were estimated based on generalized (bulk) parameterizations of microphysics from regional atmosphere models (Kessler, Beheng, and Khairutdinov-Kogan) and corresponding characteristics from the spectral (bin) cloud model. The obtained results have been analysed and the limits where the bulk parameterizations can be applied have been determined. Based on spectral model estimations new nonlinear formulations are proposed for parameterizations of sedimentation rates of droplet concentration and water content in models with bulk microphysics, but they need further approbation and estimation of biases against experimental measurements. Evolution in time and at vertical cloud levels of precipitation drops’ spectra are presented and analysed showing more natural two maxima shapes observed in clouds as a rule.

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