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Title: Clouds, aerosol, and precipitation in the Marine Boundary Layer: An ARM mobile facility deployment

The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21-month (April 2009-December 2010) comprehensive dataset documenting clouds, aerosols, and precipitation using the Atmospheric Radiation Measurement Program (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain improved understanding of the interactions of clouds, aerosols, and precipitation in the marine boundary layer. Graciosa Island straddles the boundary between the subtropics and midlatitudes in the Northeast Atlantic Ocean and consequently experiences a great diversity of meteorological and cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulus and cumulus occurring regularly. Approximately half of all clouds contained precipitation detectable as radar echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1-11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide range of aerosol conditions was sampled during the deployment consistent with the diversity of sources as indicated by back-trajectory analysis. Preliminary findings suggest important two-way interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation and cloud radiative properties while being controlled in part by precipitation scavenging.The data from Graciosa are being compared with short-rangemore » forecasts made with a variety of models. A pilot analysis with two climate and two weather forecast models shows that they reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to be a permanent fixed ARM site that became operational in October 2013.« less
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  1. Univ. of Washington, Seattle, WA (United States)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Columbia Univ., New York, NY (United States)
  4. McGill Univ., Montreal, QC (Canada)
  5. Oregon State Univ., Corvallis, OR (United States)
  6. North Carolina State Univ., Raleigh, NC (United States)
  7. Univ. of Kansas, Lawrence, KS (United States)
  8. Univ. of Reading, Reading (United Kingdom)
  9. Univ. of Reading, Reading (United Kingdom); Finnish Meteorological Institute (Finland)
  10. Univ. of North Dakota, Grand Forks, ND (United States)
  11. Rutgers Univ., New Brunswick, NJ (United States)
  12. NOAA CIRES, Boulder, CO (United States)
  13. State Univ. of New York, Albany, NY (United States)
  14. NASA Langley Research Center, Hampton, VA (United States)
  15. Science Systems and Applications, Inc., Hampton, VA (United States)
  16. Univ. of Miami, Coral Gables, FL (United States)
  17. National Center for Atmospheric Research, Boulder, CO (United States)
  18. Tsinghua Univ., Beijing (China)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0003-0007; R&D Project: 2016-BNL-EE630EECA-Budg; KP1701000
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Bulletin of the American Meteorological Society
Additional Journal Information:
Journal Volume: 96; Journal Issue: 3; Journal ID: ISSN 0003-0007
American Meteorological Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; atmospheric-ocean interaction; Hadley circulation; La Nina; meridional overturning circulation; decadal variability; Spring season