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

Abstract

In this study, marine nonprecipitating cumulus topped boundary layers (CTBLs) observed in a tropical and in a trade wind region are contrasted based on their cloud macrophysical, dynamical, and radiative structures. Data from the Atmospheric Radiation Measurement (ARM) observational site previously operating at Manus Island, Papua New Guinea, and data collected during the deployment of ARM Mobile Facility at the island of Graciosa, in the Azores, were used in this study. The tropical marine CTBLs were deeper, had higher surface fluxes and boundary layer radiative cooling, but lower wind speeds compared 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 those of trade wind cumuli, and as a result of 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 average amount of updrafts near cloud base stronger than 1 m s –1 was ~22% in tropical cumulimore » 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 a higher number of strong updrafts, due to lower cloud fraction, the updraft mass flux was lower in the tropical cumuli compared to the trade wind cumuli. The observations suggest that the tropical and trade wind marine cumulus clouds differ significantly in their macrophysical and dynamical structures« 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 Lab. (ANL), Argonne, IL (United States); Rutgers Univ., New Brunswick, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1248745
Alternate Identifier(s):
OSTI ID: 1329838
Grant/Contract Number:  
AC02-06CH11357; SC0008584; FG02-08ER64531
Resource Type:
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. doi:10.1175/MWR-D-15-0110.1.
Ghate, Virendra P., Miller, Mark A., and Zhu, Ping. Fri . "Differences between nonprecipitating tropical and trade wind marine shallow cumuli". United States. doi: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 = {In this study, marine nonprecipitating cumulus topped boundary layers (CTBLs) observed in a tropical and in a trade wind region are contrasted based on their cloud macrophysical, dynamical, and radiative structures. Data from the Atmospheric Radiation Measurement (ARM) observational site previously operating at Manus Island, Papua New Guinea, and data collected during the deployment of ARM Mobile Facility at the island of Graciosa, in the Azores, were used in this study. The tropical marine CTBLs were deeper, had higher surface fluxes and boundary layer radiative cooling, but lower wind speeds compared 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 those of trade wind cumuli, and as a result of 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 average 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 a higher number of strong updrafts, due to lower cloud fraction, the updraft mass flux was lower in the tropical cumuli compared to the trade wind cumuli. The observations suggest that the tropical and trade wind marine cumulus clouds differ significantly in their macrophysical and dynamical structures},
doi = {10.1175/MWR-D-15-0110.1},
journal = {Monthly Weather Review},
number = 2,
volume = 144,
place = {United States},
year = {2015},
month = {11}
}

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