We analyzed macrophysical characteristics of clouds and their radiative effects using COSMO mesoscale model and four German CLOUDNET sites. The study was performed for selected days with optically thick cloudiness, which relates to the period from April to October 2018. The short-term forecasts with only 3-hour time interval permit to evaluate only cloud microphysics effect on global irradiance at ground. The comparisons of liquid cloud water content (QC) and ice cloud content (QI) between measurements and modelling are discussed. We showed that the CLOUDRAD experimental cloud radiation interaction scheme provides a better agreement in global irradiance with observations than that from the default scheme.
An effect of the implementation of the new aerosol-cloud-radiation interaction scheme in the COSMO model is described. The results of simulations with the new scheme are given for various values of the aerosol concentration. The aerosol effect on the forecast of cloud microphysical characteristics and radiative fluxes was determined. The study conducted for Meteorological Observatory of Moscow State University for a warm period (April – October) 2018. Values of integral cloud water/ice content obtained in experiments with fixed cloud nuclei concentration were noticeably smaller than in experiment with aerosol climatological data. Simulations shown the decreasing of global radiation with increasing cloud particle number that is connected with increasing of the concentration of cloud nuclei. We obtain better results against observations when cloud nuclei concentration is set according to Tegen aerosol climatology compare to fixed concentration.
We analyzed clouds macrophysics and their radiative effects according to COSMO mesoscale atmospheric model and measurements at Lindenberg Observatory (Germany). Different cloud parameters simulated by the model and derived from measurements of ground-based remote sounding systems as well as by measurements of the BSRN station have been compared for snow-free conditions during March-October, 2016. We show that simulated water vapor content (QV) values were higher than the observed ones in the middle and upper troposphere. Furthermore, the modeled cloud ice water content (QI) is significantly higher at these altitudes and the ice cloud water path (TQI) is ten times higher than the observed value. Typical values of TQI and of TQC (liquid cloud water path) lie within 3*10-13-1.1 kg/m2 and 0.0017-2.9 kg/m2 , respectively with average values of 0.015 and 0.079 kg/m2 correspondingly. We also found a positive bias with the measurements for the TQC greater than 0.1 kg/m2 and a negative bias for other values. A clear nonlinear dependence of solar irradiance at ground against TQC values was obtained both from measurements and model experiments. We showed a significant (29%) underestimation of model solar irradiance for the same TQC values in overcast cloud conditions compared with the observations.
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