A comparison of sea salt emission parameterizations in Northwestern Europe using a chemistry transport model setup


Atmospheric sea salt particles affect chemical and physical processes in the atmosphere. They provide surface area for condensation and reaction of nitrogen, sulfur, and organic species and are a vehicle of transport for these species. Additionally, HCl is released from sea salt. Hence, sea salt has a relevant impact on air quality, particularly in coastal regions with high anthropogenic emissions such as in the North Sea region. Therefore, the integration of sea salt emissions in modeling studies in these regions is necessary. However, it was found that sea salt concentrations are not represented with necessary accuracy in some situations. In this study, three sea salt emission parameterizations depending on different combinations of wind speed, salinity, sea surface temperature, and wave data were implemented and compared: GO03 (Gong, 2003), SP13 (Spada et al., 2013), and OV14 (Ovadnevaite et al., 2014). The aim is to improve modeled atmospheric sea salt concentrations by identifying the parameterization that predicts the sea salt PM10 mass concentrations at different distances to the source regions most accurately and that represents atmospheric sea salt particle size distributions most appropriately in the region under consideration. While the GO03 emissions yielded overestimations in the PM10 concentrations at coastal stations and underestimations of those at inland stations, OV14 emissions, vice versa, led to underestimations at coastal stations and overestimations at inland stations. Because of differently shaped particle size distributions of the GO03 and OV14 emission cases, the deposition velocity of the coarse particles differs between both cases which yields this distinct behavior at inland and coast stations. PM10 concentrations produced by the SP13 emissions generally overestimated measured concentrations. With respect to the size distribution, OV14 produced most accurate coarse particle concentrations, whereas GO03 produced most accurate fine particle concentrations. Overall, GO03 and OV14 produced most accurate results, but both parameterizations still reveal weaknesses in some situations.
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