Dry versus wet marine particle optical properties: RH dependence of depolarization ratio, backscatter, and extinction from multiwavelength lidar measurements during SALTRACE

Autor(en)

Moritz Haarig, Albert Ansmann, Josef Gasteiger, Konrad Kandler, Dietrich Althausen, Holger Baars, Martin Radenz, David A. Farrell

Abstrakt

Triple-wavelength lidar observations of the depolarization ratio and the backscatter coefficient of marine aerosol as a function of relative humidity (RH) are presented with a 5ĝ€min time resolution. The measurements were performed at Barbados (13°ĝ€N, 59°ĝ€W) during the Saharan Aerosol Long-range Transport and Aerosol-Cloud interaction Experiment (SALTRACE) winter campaign in February 2014. The phase transition from spherical sea salt particles to cubic-like sea salt crystals was observed with a polarization lidar. The radiosonde and water-vapor Raman lidar observations show a drop in RH below 50ĝ€% in the marine aerosol layer simultaneously with a strong increase in particle linear depolarization ratio, which reaches values up to 0.12ĝ€±ĝ€0.08 (at 355ĝ€nm), 0.15ĝ€±ĝ€0.03 (at 532ĝ€nm), and 0.10ĝ€±ĝ€0.01 (at 1064ĝ€nm). The lidar ratio (extinction-To-backscatter ratio) increased from 19 and 23ĝ€sr for spherical sea salt particles to 27 and 25ĝ€sr (at 355 and 532ĝ€nm, respectively) for cubic-like particle ensembles. Furthermore the scattering enhancement due to hygroscopic growth of the marine aerosol particles under atmospheric conditions was measured. Extinction enhancement factors from 40 to 80ĝ€% RH of 1.94ĝ€±ĝ€0.94 at 355ĝ€nm, 3.70ĝ€±ĝ€1.14 at 532ĝ€nm, and 5.37ĝ€±ĝ€1.66 at 1064ĝ€nm were found. The enhanced depolarization ratios and lidar ratios were compared to modeling studies of cubic sea salt particles.

Organisation(en)

Aerosolphysik und Umweltphysik

Externe Organisation(en)

Leibniz-Institut für Troposphärenforschung, Technische Universität Darmstadt, Caribbean Institute for Meteorology and Hydrology

Journal

Atmospheric Chemistry and Physics

Band

17

Seiten

14199-14217

Anzahl der Seiten

19

ISSN

1680-7316

DOI

https://doi.org/10.5194/acp-17-14199-2017

Publikationsdatum

11-2017

Peer-reviewed

Ja

ÖFOS 2012

103037 Umweltphysik, 103039 Aerosolphysik, 105206 Meteorologie

Schlagwörter

ASJC Scopus Sachgebiete

Atmospheric Science

Sustainable Development Goals

SDG 14 – Leben unter Wasser

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/b11bb021-b29e-41d2-9eee-b86d77d3dcf2