Remote Sensing of Sea Salt Aerosol below Trade Wind Clouds

Journal Article · 28 April 2019 · Journal of the Atmospheric Sciences

DOI: https://doi.org/10.1175/JAS-D-18-0139.1 · OSTI ID:1509768

Klingebiel, Marcus ^[1]; Ghate, Virendra P. ^[2]; Naumann, Ann Kristin ^[1]; Ditas, Florian ^[3]; Pöhlker, Mira L. ^[3]; Pöhlker, Christopher ^[3]; Kandler, Konrad ^[4]; Konow, Heike ^[5]; Stevens, Bjorn ^[1]

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1. Max-Planck-Institut für Meteorologie, Hamburg, Germany
2. Argonne National Laboratory, Argonne, Illinois
3. Max-Planck-Institut für Chemie, Mainz, Germany
4. Technische Universität Darmstadt, Darmstadt, Germany
5. Universität Hamburg, Hamburg, Germany

Abstract Sea salt aerosol in the boundary layer below shallow cumulus clouds is remotely observed with a Ka-band cloud radar at the Barbados Cloud Observatory and is detected in 76% of the measurements over 1 year. Carried by convection, sea salt particles with a diameter larger than 500 nm show an upward motion of 0.2 m s−1 below shallow cumulus clouds for a 2-day case study. Caused by an increasing relative humidity with increasing altitude, the sea salt particles become larger as they move closer to the cloud base. By using combined measurements of a Ka-band cloud radar and a Raman lidar, the retrieved equivolumetric diameter of the hygroscopically grown sea salt particles is found to be between 6 and 11 μm with a total number concentration of 20 cm−3 near cloud base. Assuming a fixed shape parameter, a size distribution of sea salt particles under high-relative-humidity conditions below cloud base is estimated and agrees with measurements taken by a dry-deposition sampler and online aerosol observations. The methods outlined in this paper can be used in future studies to get a better understanding of the vertical and temporal sea salt distribution in the boundary layer and sea salt aerosol–cloud interaction processes.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1509768
• Journal Information: Journal of the Atmospheric Sciences, Journal Name: Journal of the Atmospheric Sciences Journal Issue: 5 Vol. 76; ISSN 0022-4928
• Publisher: American Meteorological SocietyCopyright Statement
• Country of Publication: United States
• Language: English