Variations in raindrop size distributions observed in mid-latitude ocean clouds during the East-Asian summer monsoon

The temporal variations in raindrop size distributions (RSDs) observed during the East-Asian summer monsoon have been considered for the statistical procedure called the principal component analysis (PCA). This statistical examination reveals the most important factors in the RSD's variations and helps to critically re-evaluate the known RSD-parameterization models. Based on the results of the PCA applied to the medium-size dataset, it has been concluded that the most frequently used parametric shapes of RSDs present significant simplifications of the experimentally observed RSD variance. The simplifications are seen in the type and number of the parameters employed for the typical parameterization models. As a result of this study, four principal factors are revealed which might be used for a new RSD-parameterization model covering more than 80% of the observed RSD variance.