Abstract
Atmospheric sea salt particles affect chemical and physical processes in the
atmosphere. These particles provide surface area for condensation and
reaction of nitrogen, sulfur, and organic species and are a vehicle for the
transport of 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 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 the 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 was to
identify the parameterization that most accurately predicts the sea salt mass
concentrations at different distances to the source regions. For this
purpose, modeled particle sodium concentrations, sodium wet deposition, and
aerosol optical depth were evaluated against measurements of these
parameters. Each 2-month period in winter and summer 2008
were considered for this purpose. The shortness of these periods limits
generalizability of the conclusions on other years.
While the GO03 emissions yielded overestimations in the PM10
concentrations at coastal stations and underestimations of those at inland
stations, OV14 emissions conversely led to underestimations at coastal
stations and overestimations at inland stations. Because of the differently
shaped particle size distributions of the GO03 and OV14 emission cases, the
deposition velocity of the coarse particles differed between both cases which
yielded this distinct behavior at inland and coastal stations. The PM10
concentrations produced by the SP13 emissions generally overestimated the
measured concentrations. The sodium wet deposition was generally
underestimated by the model simulations but the SP13 cases yielded the least
underestimations. Because the model tends to underestimate wet deposition,
this result needs to be considered critically. Measurements of the aerosol
optical depth (AOD) were underestimated by all model cases in the summer and
partly in winter. None of the model cases clearly improved the modeled AODs.
Overall, GO03 and OV14 produced the most accurate results, but both
parameterizations revealed weaknesses in some situations.
Citation
ID:
190345
Ref Key:
neumann2016atmospherica