Progress on predicting the breadth of droplet size distributions observed in small cumuli

Jennifer L. Bewley, Sonia Lasher-Trapp

Research output: Contribution to journalArticlepeer-review

Abstract

A modeling framework representing variations in droplet growth by condensation, resulting from different saturation histories experienced as a result of entrainment and mixing, is used to predict the breadth of droplet size distributions observed at different altitudes within trade wind cumuli observed on 10 December 2004 during the Rain in Cumulus over the Ocean (RICO) field campaign. The predicted droplet size distributions are as broad as those observed, contain similar numbers of droplets, and are generally in better agreement with the observations when some degree of inhomogeneous droplet evaporation is considered, allowing activation of newly entrained cloud condensation nuclei. The variability of the droplet growth histories, resulting primarily from entrainment, appears to explain the magnitude of the observed droplet size distribution widths, without representation of other broadening mechanisms. Additional work is needed, however, as the predicted mean droplet diameter is too large relative to the observations and likely results from the model resolution limiting dilution of the simulated cloud.

Original languageEnglish (US)
Pages (from-to)2921-2929
Number of pages9
JournalJournal of the Atmospheric Sciences
Volume68
Issue number12
DOIs
StatePublished - Dec 2011
Externally publishedYes

Keywords

  • Aircraft observations
  • Cloud droplets
  • Cloud resolving models
  • Cumulus clouds
  • Drop size distribution
  • Entrainment

ASJC Scopus subject areas

  • Atmospheric Science

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