LACIS-measurements and parameterization of sea-salt particle hygroscopic growth and activation

D. Niedermeier (1) , F. Stratmann (1) , H. Wex (1) , E. Brüggemann (1) , A. Kiselev (1) , H. Henk (1) , J. Heintzenberg (1)

1 TROPOS - Leibniz Institute for Tropospheric Research

The Leipzig Aerosol Cloud Interaction Simulator (LACIS) was used to investigate the hygroscopic growth and activation of sea-salt particles which were generated from three different sea-water samples. Köhler theory was utilized to model the hygroscopic growth of these particles. Some parameters used in this model are unknown for sea-salt. These parameters are combined in an "ionic density" ?_ion. For each sea-salt sample an average ?_ion was determined by fitting the Köhler equation to the data from the hygroscopic growth measurements. LACIS was also used to measure the activation of the sea-salt particles at three different supersaturations: 0.10%, 0.16% and 0.30%. A CCN-closure was tested by calculating the critical diameters D_crit for the sea-salt particles at these supersaturations, using the Köhler model and the corresponding ?_ion as derived from the hygroscopic growth data. These calculated critical diameters were compared to the measured ones. Measured and calculated values of D_crit agree within the level of uncertainty. Based on this successful closure, a new parameterization to describe sea-salt-particle hygroscopic growth (at RH>95%) and activation has been developed.

Domaines: Océan, Atmosphère

D. Niedermeier, F. Stratmann, H. Wex, E. Brüggemann, A. Kiselev, et al.. LACIS-measurements and parameterization of sea-salt particle hygroscopic growth and activation. Atmospheric Chemistry and Physics Discussions, 2007, 7 (4), pp.11511-11544. ⟨hal-00303029⟩