The distribution of sea-salt aerosol in the global troposphere

Murphy, D., K.D. Froyd, H. Bian, C.A. Brock, J.E. Dibb, J.P. DiGangi, G.S. Diskin, M. Dollner , A. Kupc, E. Scheuer, G.P. Schill, B.B. Weinzierl, C.J. Williamson, and P. Yu (2019), The distribution of sea-salt aerosol in the global troposphere, Atmos. Chem. Phys., 19, 4093-4104, doi:10.5194/acp-19-4093-2019.
Abstract

We present the first data on the concentration of sea-salt aerosol throughout most of the depth of the troposphere and over a wide range of latitudes, which were obtained during the Atmospheric Tomography (ATom) mission. Sea-salt concentrations in the upper troposphere are very small, usually less than 10 ng per standard m3 (about 10 parts per trillion by mass) and often less than 1 ng m−3 . This puts stringent limits on the contribution of sea-salt aerosol to halogen and nitric acid chemistry in the upper troposphere. Within broad regions the concentration of sea-salt aerosol is roughly proportional to water vapor, supporting a dominant role for wet scavenging in removing sea-salt aerosol from the atmosphere. Concentrations of sea-salt aerosol in the winter upper troposphere are not as low as in the summer and the tropics. This is mostly a consequence of less wet scavenging in the drier, colder winter atmosphere. There is also a source of sea-salt aerosol over pack ice that is distinct from that over open water. With a well-studied and widely distributed source, sea-salt aerosol provides an excellent test of wet scavenging and vertical transport of aerosols in chemical transport models.

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Research Program
Tropospheric Composition Program (TCP)
Mission
ATom