On the influence of raindrop collision outcomes on equilibrium drop size distributions

Olivier P. Prat, Ana P. Barros, Firat Y. Testik

Research output: Contribution to journalArticlepeer-review


The objective of this study is to evaluate the impact of a new parameterization of drop-drop collision outcomes based on the relationship between Weber number and drop diameter ratios on the dynamical simulation of raindrop size distributions. Results of the simulations with the new parameterization are compared with those of the classical parameterizations. Comparison with previous results indicates on average an increase of 70% in the drop number concentration and a 15% decrease in rain intensity for the equilibrium drop size distribution (DSD). Furthermore, the drop bounce process is parameterized as a function of drop size based on laboratory experiments for the first time in a microphysical model. Numerical results indicate that drop bounce has a strong influence on the equilibrium DSD, in particular for very small drops (,0.5 mm), leading to an increase of up to 150% in the small drop number concentration (left-hand side of the DSD) when compared to previous modeling results without accounting for bounce effects.

Original languageEnglish (US)
Pages (from-to)1534-1546
Number of pages13
JournalJournal of the Atmospheric Sciences
Issue number5
StatePublished - May 2012
Externally publishedYes


  • Cloud microphysics
  • Cloud parameterizations
  • Drop size distribution

ASJC Scopus subject areas

  • Atmospheric Science


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