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Title: Analysis of Cloud-Resolving Model Simulations for Scale Dependence of Convective Momentum Transport

Abstract

In this study, we use 3D cloud-resolving model (CRM) simulations of two mesoscale convective systems at midlatitudes and a simple statistical ensemble method to diagnose the scale dependency of convective momentum transport (CMT) and CMT-related properties and evaluate a parameterization scheme for the convection-induced pressure gradient (CIPG) developed by Gregory et al. Gregory et al. relate CIPG to a constant coefficient multiplied by mass flux and vertical mean wind shear. CRM results show that mass fluxes and CMT exhibit strong scale dependency in temporal evolution and vertical structure. The upgradient–downgradient CMT characteristics for updrafts are generally similar between small and large grid spacings, which is consistent with previous understanding, but they can be different for downdrafts across wide-ranging grid spacings. For the small to medium grid spacings (4–64 km), Gregory et al. reproduce some aspects of CIPG scale dependency except for underestimating the variations of CIPG as grid spacing decreases. However, for large grid spacings (128–512 km), Gregory et al. might even less adequately parameterize CIPG because it omits the contribution from either the nonlinear-shear or the buoyancy forcings. Further diagnosis of CRM results suggests that inclusion of nonlinear-shear forcing in Gregory et al. is needed for the large gridmore » spacings. For the small to median grid spacings, a modified Gregory et al. with the three-updraft approach help better capture the variations of CIPG as grid spacing decreases compared to the single updraft approach. Further, the optimal coefficients used in Gregory et al. seem insensitive to grid spacings, but they might be different for updrafts and downdrafts, for different MCS types, and for zonal and meridional components.« less

Authors:
 [1];  [2];  [3];  [4]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); California Environmental Protection Agency, Sacramento, CA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. NASA Langley Research Center, Hampton, VA (United States)
  4. University of California, San Diego, La Jolla, CA (United States)
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1459701
Alternate Identifier(s):
OSTI ID: 1492412
Report Number(s):
PNNL-SA-119826
Journal ID: ISSN 0022-4928
Grant/Contract Number:  
AC05-76RL01830; 62201
Resource Type:
Published Article
Journal Name:
Journal of the Atmospheric Sciences
Additional Journal Information:
Journal Volume: 75; Journal Issue: 7; Journal ID: ISSN 0022-4928
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Cloud parameterizations; Cloud resolving models; Convective parameterization; Cumulus clouds

Citation Formats

Liu, Yi-Chin, Fan, Jiwen, Xu, Kuan-Man, and Zhang, Guang J. Analysis of Cloud-Resolving Model Simulations for Scale Dependence of Convective Momentum Transport. United States: N. p., 2018. Web. doi:10.1175/JAS-D-18-0019.1.
Liu, Yi-Chin, Fan, Jiwen, Xu, Kuan-Man, & Zhang, Guang J. Analysis of Cloud-Resolving Model Simulations for Scale Dependence of Convective Momentum Transport. United States. doi:10.1175/JAS-D-18-0019.1.
Liu, Yi-Chin, Fan, Jiwen, Xu, Kuan-Man, and Zhang, Guang J. Tue . "Analysis of Cloud-Resolving Model Simulations for Scale Dependence of Convective Momentum Transport". United States. doi:10.1175/JAS-D-18-0019.1.
@article{osti_1459701,
title = {Analysis of Cloud-Resolving Model Simulations for Scale Dependence of Convective Momentum Transport},
author = {Liu, Yi-Chin and Fan, Jiwen and Xu, Kuan-Man and Zhang, Guang J.},
abstractNote = {In this study, we use 3D cloud-resolving model (CRM) simulations of two mesoscale convective systems at midlatitudes and a simple statistical ensemble method to diagnose the scale dependency of convective momentum transport (CMT) and CMT-related properties and evaluate a parameterization scheme for the convection-induced pressure gradient (CIPG) developed by Gregory et al. Gregory et al. relate CIPG to a constant coefficient multiplied by mass flux and vertical mean wind shear. CRM results show that mass fluxes and CMT exhibit strong scale dependency in temporal evolution and vertical structure. The upgradient–downgradient CMT characteristics for updrafts are generally similar between small and large grid spacings, which is consistent with previous understanding, but they can be different for downdrafts across wide-ranging grid spacings. For the small to medium grid spacings (4–64 km), Gregory et al. reproduce some aspects of CIPG scale dependency except for underestimating the variations of CIPG as grid spacing decreases. However, for large grid spacings (128–512 km), Gregory et al. might even less adequately parameterize CIPG because it omits the contribution from either the nonlinear-shear or the buoyancy forcings. Further diagnosis of CRM results suggests that inclusion of nonlinear-shear forcing in Gregory et al. is needed for the large grid spacings. For the small to median grid spacings, a modified Gregory et al. with the three-updraft approach help better capture the variations of CIPG as grid spacing decreases compared to the single updraft approach. Further, the optimal coefficients used in Gregory et al. seem insensitive to grid spacings, but they might be different for updrafts and downdrafts, for different MCS types, and for zonal and meridional components.},
doi = {10.1175/JAS-D-18-0019.1},
journal = {Journal of the Atmospheric Sciences},
number = 7,
volume = 75,
place = {United States},
year = {2018},
month = {7}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1175/JAS-D-18-0019.1

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