|Title||Sea spray aerosol as a unique source of ice nucleating particles|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||DeMott PJ, Hill T.CJ, McCluskey C.S, Prather KA, Collins DB, Sullivan RC, Ruppel MJ, Mason R.H, Irish V.E, Lee T., Hwang C.Y, Rhee T.S, Snider J.R, McMeeking G.R, Dhaniyala S., Lewis E.R, Wentzell JJB, Abbatt J., Lee C., Sultana C.M, Ault AP, Axson J.L, Martinez M.D, Venero I., Santos-Figueroa G., Stokes MD, Deane GB, Mayol-Bracero O.L, Grassian VH, Bertram TH, Bertram A.K, Moffett B.F, Franc G.D|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Type of Article||Article|
|Keywords||chemical-composition; cloud; Clouds; dust; forming nuclei; hygroscopic growth; ice nucleation; marine aerosols; marine air; nuclei; populations; precipitation; rain; size-distribution|
Ice nucleating particles (INPs) are vital for ice initiation in, and precipitation from, mixed-phase clouds. A source of INPs from oceans within sea spray aerosol (SSA) emissions has been suggested in previous studies but remained unconfirmed. Here, we show that INPs are emitted using real wave breaking in a laboratory flume to produce SSA. The number concentrations of INPs from laboratory-generated SSA, when normalized to typical total aerosol number concentrations in the marine boundary layer, agree well with measurements from diverse regions over the oceans. Data in the present study are also in accord with previously published INP measurements made over remote ocean regions. INP number concentrations active within liquid water droplets increase exponentially in number with a decrease in temperature below 0 degrees C, averaging an order of magnitude increase per 5 degrees C interval. The plausibility of a strong increase in SSA INP emissions in association with phytoplankton blooms is also shown in laboratory simulations. Nevertheless, INP number concentrations, or active site densities approximated using "dry" geometric SSA surface areas, are a few orders of magnitude lower than corresponding concentrations or site densities in the surface boundary layer over continental regions. These findings have important implications for cloud radiative forcing and precipitation within low-level and midlevel marine clouds unaffected by continental INP sources, such as may occur over the Southern Ocean.