Entrainment versus Dilution in Tropical Deep Convection
Abstract
Abstract The distinction between entrainment and dilution is investigated with cloud-resolving simulations of deep convection in a tropical environment. A method for estimating the rate of dilution by entrainment and detrainment is presented and calculated for a series of bubble simulations with a range of initial radii. Entrainment generally corresponds to dilution of convection, but the two quantities are not well correlated. Core dilution by entrainment is significantly reduced by the presence of a shell of moist air around the core. Dilution by entrainment also increases with increasing updraft velocity but only for sufficiently strong updrafts. Entrainment contributes significantly to the total net dilution, but detrainment and the various source/sink terms play large roles depending on the variable in question. Detrainment has a concentrating effect on average that balances out the dilution by entrainment. The experiments are also used to examine whether entrainment or dilution scale with cloud radius. The results support a weak negative relationship for dilution but not for entrainment. The sensitivity to resolution is briefly discussed. A toy Lagrangian thermal model is used to demonstrate the importance of the cloud shell as a thermodynamic buffer to reduce the dilution of the core by entrainment. The results suggestmore »
- Authors:
-
- Lawrence Livermore National Laboratory, Livermore, California
- Publication Date:
- Research Org.:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Org.:
- USDOE; National Science Foundation (NSF); National Oceanic and Atmospheric Administration (NOAA) (United States)
- OSTI Identifier:
- 1406397
- Alternate Identifier(s):
- OSTI ID: 1438657
- Report Number(s):
- LLNL-JRNL-737793
Journal ID: ISSN 0022-4928
- Grant/Contract Number:
- AC52-07NA27344; AGS-1441916; ATM-0425247; 1433343; NA13OAR4310163; NA12OAR4310077
- Resource Type:
- Published Article
- Journal Name:
- Journal of the Atmospheric Sciences
- Additional Journal Information:
- Journal Name: Journal of the Atmospheric Sciences Journal Volume: 74 Journal Issue: 11; Journal ID: ISSN 0022-4928
- Publisher:
- American Meteorological Society
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; convection; entrainment; cloud resolving models
Citation Formats
Hannah, Walter M. Entrainment versus Dilution in Tropical Deep Convection. United States: N. p., 2017.
Web. doi:10.1175/JAS-D-16-0169.1.
Hannah, Walter M. Entrainment versus Dilution in Tropical Deep Convection. United States. https://doi.org/10.1175/JAS-D-16-0169.1
Hannah, Walter M. Wed .
"Entrainment versus Dilution in Tropical Deep Convection". United States. https://doi.org/10.1175/JAS-D-16-0169.1.
@article{osti_1406397,
title = {Entrainment versus Dilution in Tropical Deep Convection},
author = {Hannah, Walter M.},
abstractNote = {Abstract The distinction between entrainment and dilution is investigated with cloud-resolving simulations of deep convection in a tropical environment. A method for estimating the rate of dilution by entrainment and detrainment is presented and calculated for a series of bubble simulations with a range of initial radii. Entrainment generally corresponds to dilution of convection, but the two quantities are not well correlated. Core dilution by entrainment is significantly reduced by the presence of a shell of moist air around the core. Dilution by entrainment also increases with increasing updraft velocity but only for sufficiently strong updrafts. Entrainment contributes significantly to the total net dilution, but detrainment and the various source/sink terms play large roles depending on the variable in question. Detrainment has a concentrating effect on average that balances out the dilution by entrainment. The experiments are also used to examine whether entrainment or dilution scale with cloud radius. The results support a weak negative relationship for dilution but not for entrainment. The sensitivity to resolution is briefly discussed. A toy Lagrangian thermal model is used to demonstrate the importance of the cloud shell as a thermodynamic buffer to reduce the dilution of the core by entrainment. The results suggest that explicit cloud heterogeneity may be a useful consideration for future convective parameterization development.},
doi = {10.1175/JAS-D-16-0169.1},
journal = {Journal of the Atmospheric Sciences},
number = 11,
volume = 74,
place = {United States},
year = {Wed Nov 01 00:00:00 EDT 2017},
month = {Wed Nov 01 00:00:00 EDT 2017}
}
https://doi.org/10.1175/JAS-D-16-0169.1
Search WorldCat to find libraries that may hold this journalWeb of Science
Works referencing / citing this record:
Ongoing Breakthroughs in Convective Parameterization
journal, April 2019
- Rio, Catherine; Del Genio, Anthony D.; Hourdin, Frédéric
- Current Climate Change Reports, Vol. 5, Issue 2
Evaluation of Shallow‐Cumulus Entrainment Rate Retrievals Using Large‐Eddy Simulation
journal, August 2019
- Drueke, S.; Kirshbaum, D. J.; Kollias, P.
- Journal of Geophysical Research: Atmospheres, Vol. 124, Issue 16
Core and margin in warm convective clouds – Part 1: Core types and evolution during a cloud's lifetime
journal, January 2019
- Heiblum, Reuven H.; Pinto, Lital; Altaratz, Orit
- Atmospheric Chemistry and Physics, Vol. 19, Issue 16