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Title: Differences between nonprecipitating tropical and trade wind marine shallow cumuli

Abstract

Marine nonprecipitating cumulus topped boundary layers (CTBL) observed in a tropical and in a trade-wind region are contrasted based on their cloud macro-physical, dynamical, and radiative structures. Data from the Atmospheric Radiation Measurement (ARM) observational site previously operating at Manus Island and data collected during the deployment of ARM Mobile Facility at the island of Graciosa were used in this study. The tropical marine CTBL were deeper, had higher surface fluxes and boundary layer radiative cooling, but lower wind speeds compared 8 to their trade-wind counterparts. The radiative velocity scale was 50-70% of the surface convective velocity scale at both locations, highlighting the prominent role played by radiation in maintaining turbulence in marine CTBLs. Despite greater thicknesses, the chord lengths of tropical cumuli were on average lower than that of trade wind cumuli, and due to lower cloud cover, the hourly averaged (cloudy and clear) liquid water paths of tropical cumuli were lower than the trade-wind cumuli. At both locations ~70% of the cloudy profiles were updrafts, while the averaged amount of updrafts near cloud base stronger than 1 m s-1 was ~22% in tropical cumuli and ~12% in the trade-wind cumuli. The mean in-cloud radar reflectivity within updrafts andmore » mean updraft velocity was higher in tropical cumuli than the trade-wind cumuli. Despite stronger vertical velocities and more amount of strong updrafts, due to lower cloud fraction, the updraft mass-flux was lower in tropical cumuli compared to the trade-wind cumuli. The observations suggest the tropical and trade-wind marine cumulus clouds to differ significantly in their macro-physical and dynamical structure.« less

Authors:
 [1];  [2];  [3]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. The State Univ. of New Jersey, New Brunswick, NJ (United States)
  3. Florida International Univ., University Park, FL (United States)
Publication Date:
Research Org.:
Argonne National Laboratory (ANL), Argonne, IL (United States); Rutgers Univ., New Brunswick, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER)
OSTI Identifier:
1248745
Alternate Identifier(s):
OSTI ID: 1329838
Grant/Contract Number:  
AC02-06CH11357; SC0008584; FG02-08ER64531
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Monthly Weather Review
Additional Journal Information:
Journal Volume: 144; Journal Issue: 2; Journal ID: ISSN 0027-0644
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; cumulus clouds; Atm/ocean structure/phenomena; boundary layer; physical meteorology and climatology; cloud radiative effects; clouds; Cumulus; Climate; Mass flux; Tropical; Atm/Ocean Structure/ Phenomena

Citation Formats

Ghate, Virendra P., Miller, Mark A., and Zhu, Ping. Differences between nonprecipitating tropical and trade wind marine shallow cumuli. United States: N. p., 2015. Web. doi:10.1175/MWR-D-15-0110.1.
Ghate, Virendra P., Miller, Mark A., & Zhu, Ping. Differences between nonprecipitating tropical and trade wind marine shallow cumuli. United States. https://doi.org/10.1175/MWR-D-15-0110.1
Ghate, Virendra P., Miller, Mark A., and Zhu, Ping. 2015. "Differences between nonprecipitating tropical and trade wind marine shallow cumuli". United States. https://doi.org/10.1175/MWR-D-15-0110.1. https://www.osti.gov/servlets/purl/1248745.
@article{osti_1248745,
title = {Differences between nonprecipitating tropical and trade wind marine shallow cumuli},
author = {Ghate, Virendra P. and Miller, Mark A. and Zhu, Ping},
abstractNote = {Marine nonprecipitating cumulus topped boundary layers (CTBL) observed in a tropical and in a trade-wind region are contrasted based on their cloud macro-physical, dynamical, and radiative structures. Data from the Atmospheric Radiation Measurement (ARM) observational site previously operating at Manus Island and data collected during the deployment of ARM Mobile Facility at the island of Graciosa were used in this study. The tropical marine CTBL were deeper, had higher surface fluxes and boundary layer radiative cooling, but lower wind speeds compared 8 to their trade-wind counterparts. The radiative velocity scale was 50-70% of the surface convective velocity scale at both locations, highlighting the prominent role played by radiation in maintaining turbulence in marine CTBLs. Despite greater thicknesses, the chord lengths of tropical cumuli were on average lower than that of trade wind cumuli, and due to lower cloud cover, the hourly averaged (cloudy and clear) liquid water paths of tropical cumuli were lower than the trade-wind cumuli. At both locations ~70% of the cloudy profiles were updrafts, while the averaged amount of updrafts near cloud base stronger than 1 m s-1 was ~22% in tropical cumuli and ~12% in the trade-wind cumuli. The mean in-cloud radar reflectivity within updrafts and mean updraft velocity was higher in tropical cumuli than the trade-wind cumuli. Despite stronger vertical velocities and more amount of strong updrafts, due to lower cloud fraction, the updraft mass-flux was lower in tropical cumuli compared to the trade-wind cumuli. The observations suggest the tropical and trade-wind marine cumulus clouds to differ significantly in their macro-physical and dynamical structure.},
doi = {10.1175/MWR-D-15-0110.1},
url = {https://www.osti.gov/biblio/1248745}, journal = {Monthly Weather Review},
issn = {0027-0644},
number = 2,
volume = 144,
place = {United States},
year = {Fri Nov 13 00:00:00 EST 2015},
month = {Fri Nov 13 00:00:00 EST 2015}
}

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Works referenced in this record:

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Works referencing / citing this record:

EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation
journal, September 2017


Drizzle and Turbulence Below Closed Cellular Marine Stratocumulus Clouds
journal, June 2019