3 years ago

Observational study of the relationship between entrainment rate and relative dispersion in deep convective clouds

This study investigates the influence of entrainment rate (λ) on relative dispersion (ε) of cloud droplet size distributions (CDSD) in the 99 growing precipitating deep convective clouds during TOGA-COARE. The results show that entrainment suppresses ε, which is opposite to the traditional understanding that entrainment-mixing broadens CDSD. To examine how the relationship between ε and λ is affected by droplets with different sizes, CDSDs are divided into three portions with droplet radius<3.75μm (N 1), radius in the range of 3.75–12.75μm (N 2) and 12.75–23.25μm (N 3), respectively. The results indicate that although the droplet concentration at different sizes generally decrease simultaneously as λ increases, the variation of standard deviation (σ) depends mainly on N 3, while the mean radius (r m) decreases with decreasing N 3, but increases with decreasing N 1. So the influence of entrainment on CDSD causes a more dramatical decrease in σ than that in r m, and further leads to the decrease of ε as entrainment enhances. In addition, a conceptual model of CDSD evolution during entrainment-mixing processes is developed to illustrate the possible scenarios entailing different relationships between ε and λ. The number concentration of small droplets and the degree of evaporation of small droplets are found to be key factors that shift the sign (i.e., positive or negative) of the ε-λ relationship.

Publisher URL: www.sciencedirect.com/science

DOI: S0169809517303642

You might also like
Never Miss Important Research

Researcher is an app designed by academics, for academics. Create a personalised feed in two minutes.
Choose from over 15,000 academics journals covering ten research areas then let Researcher deliver you papers tailored to your interests each day.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.