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Title: Effects of mesoscale convective organization and vertical wind shear on the cumulus-environment interaction

Abstract

This study is made to understand the thermodynamic and dynamic aspects of cumulus-environment interaction. Specifically, the author examines (1) the similarities and differences of cumulus-environment interactions in the tropical and midlatitude convective systems (2) the impact of the presence of mesoscale circulations on the interpretation of cumulus-environment interaction, and (3) the effects of vertical wind shear on the dynamic interaction of cumulus convection with the large-scale motion. Analysis of PRE-STORM and GATE data show larger moist convective instability, large-scale forcing and vertical wind shear in the mid-latitude MCCs and squall lines than in the tropical non-squall clusters. The interaction mechanism based on the cumulus-induced subsidence and detrainment is capable of explaining most of the observed heating and drying under widely different environment conditions. The Arakawa-Schubert (A-S) quasi-equilibrium assumption is valid. Both the cumulus and stratiform cloud effects are stronger in midlatitude convective systems than in tropical systems. The heat and moisture budget results using the fine resolution SESAME data show pronounced dipole patterns in the horizontal distributions of vertically integrated heat source and moisture sink. Further analysis shows that the dipole pattern is closely related to the horizontal fluxes of heat and moisture due to mesoscale circulations. The quasi-equilibrium assumptionmore » becomes more accurate for the data resolving mesoscale circulation. The inclusion of downdrafts is required to accurately predict the cumulus heating and drying. Significant differences are found in vertical transport of horizontal momentum between the MCC and squall line. A new cloud momentum model which includes the convective-scale horizontal pressure gradient force has been developed. The application of the new cloud momentum model shows that the new model can simulate both the upgradient and downgradient transport of cloud momentum.« less

Authors:
Publication Date:
Research Org.:
California Univ., Los Angeles, CA (United States)
OSTI Identifier:
6882388
Resource Type:
Miscellaneous
Resource Relation:
Other Information: Thesis (Ph.D.)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; EARTH ATMOSPHERE; ATMOSPHERIC CIRCULATION; NATURAL CONVECTION; STORMS; LATITUDE EFFECT; CLOUDS; DATA ANALYSIS; METEOROLOGY; SHEAR; TROPICAL REGIONS; WIND; CONVECTION; DISASTERS; ENERGY TRANSFER; GEOGRAPHICAL VARIATIONS; HEAT TRANSFER; MASS TRANSFER; VARIATIONS; 540110*

Citation Formats

Wu, Xiaoqing. Effects of mesoscale convective organization and vertical wind shear on the cumulus-environment interaction. United States: N. p., 1992. Web.
Wu, Xiaoqing. Effects of mesoscale convective organization and vertical wind shear on the cumulus-environment interaction. United States.
Wu, Xiaoqing. 1992. "Effects of mesoscale convective organization and vertical wind shear on the cumulus-environment interaction". United States.
@article{osti_6882388,
title = {Effects of mesoscale convective organization and vertical wind shear on the cumulus-environment interaction},
author = {Wu, Xiaoqing},
abstractNote = {This study is made to understand the thermodynamic and dynamic aspects of cumulus-environment interaction. Specifically, the author examines (1) the similarities and differences of cumulus-environment interactions in the tropical and midlatitude convective systems (2) the impact of the presence of mesoscale circulations on the interpretation of cumulus-environment interaction, and (3) the effects of vertical wind shear on the dynamic interaction of cumulus convection with the large-scale motion. Analysis of PRE-STORM and GATE data show larger moist convective instability, large-scale forcing and vertical wind shear in the mid-latitude MCCs and squall lines than in the tropical non-squall clusters. The interaction mechanism based on the cumulus-induced subsidence and detrainment is capable of explaining most of the observed heating and drying under widely different environment conditions. The Arakawa-Schubert (A-S) quasi-equilibrium assumption is valid. Both the cumulus and stratiform cloud effects are stronger in midlatitude convective systems than in tropical systems. The heat and moisture budget results using the fine resolution SESAME data show pronounced dipole patterns in the horizontal distributions of vertically integrated heat source and moisture sink. Further analysis shows that the dipole pattern is closely related to the horizontal fluxes of heat and moisture due to mesoscale circulations. The quasi-equilibrium assumption becomes more accurate for the data resolving mesoscale circulation. The inclusion of downdrafts is required to accurately predict the cumulus heating and drying. Significant differences are found in vertical transport of horizontal momentum between the MCC and squall line. A new cloud momentum model which includes the convective-scale horizontal pressure gradient force has been developed. The application of the new cloud momentum model shows that the new model can simulate both the upgradient and downgradient transport of cloud momentum.},
doi = {},
url = {https://www.osti.gov/biblio/6882388}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 1992},
month = {Wed Jan 01 00:00:00 EST 1992}
}

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