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Title: Dependence of entrainment in shallow cumulus convection on vertical velocity and distance to cloud edge

Here, the dependence of entrainment rate on environmental conditions and cloud characteristics is investigated using large eddy simulations (LES) of the response of shallow cumulus convection to a small-amplitude temperature perturbation that is horizontally uniform and localized in height. The simulated cumulus fields are analyzed in the framework of an ensemble of entraining plumes by tracking a large number of Lagrangian parcels embedded in the LES and grouping them into different plumes based on their detrainment heights. The results show that fractional entrainment rate per unit height of a plume is inversely proportional to the plume’s vertical velocity and its distance to the cloud edge, while changes in environmental stratification and relative humidity, the plume’s buoyancy, or the vertical gradient of its buoyancy due to the temperature perturbation have little effect on the plume’s entrainment rate.
Authors:
 [1] ;  [2]
  1. Harvard Univ., Cambridge, MA (United States). Dept. of Earth and Planetary Sciences
  2. Harvard Univ., Cambridge, MA (United States). John A. Paulson School of Engineering and Applied Sciences and Dept. of Earth and Planetary Sciences
Publication Date:
Grant/Contract Number:
SC0008679; NA13OAR4310154; AGS‐1260380
Type:
Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 43; Journal Issue: 8; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Research Org:
Harvard Univ., Cambridge, MA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; entrainment; shallow cumulus convection; lagrangian particle dispersion model; cloud-resolving model
OSTI Identifier:
1469308

Tian, Yang, and Kuang, Zhiming. Dependence of entrainment in shallow cumulus convection on vertical velocity and distance to cloud edge. United States: N. p., Web. doi:10.1002/2016GL069005.
Tian, Yang, & Kuang, Zhiming. Dependence of entrainment in shallow cumulus convection on vertical velocity and distance to cloud edge. United States. doi:10.1002/2016GL069005.
Tian, Yang, and Kuang, Zhiming. 2016. "Dependence of entrainment in shallow cumulus convection on vertical velocity and distance to cloud edge". United States. doi:10.1002/2016GL069005. https://www.osti.gov/servlets/purl/1469308.
@article{osti_1469308,
title = {Dependence of entrainment in shallow cumulus convection on vertical velocity and distance to cloud edge},
author = {Tian, Yang and Kuang, Zhiming},
abstractNote = {Here, the dependence of entrainment rate on environmental conditions and cloud characteristics is investigated using large eddy simulations (LES) of the response of shallow cumulus convection to a small-amplitude temperature perturbation that is horizontally uniform and localized in height. The simulated cumulus fields are analyzed in the framework of an ensemble of entraining plumes by tracking a large number of Lagrangian parcels embedded in the LES and grouping them into different plumes based on their detrainment heights. The results show that fractional entrainment rate per unit height of a plume is inversely proportional to the plume’s vertical velocity and its distance to the cloud edge, while changes in environmental stratification and relative humidity, the plume’s buoyancy, or the vertical gradient of its buoyancy due to the temperature perturbation have little effect on the plume’s entrainment rate.},
doi = {10.1002/2016GL069005},
journal = {Geophysical Research Letters},
number = 8,
volume = 43,
place = {United States},
year = {2016},
month = {4}
}