Abstract
Abstract. Fluxes of sea spray aerosols were measured with the eddy covariance technique from the Penlee Point Atmospheric Observatory (PPAO) on the southwest coast of the United Kingdom over several months from 2015 to 2017. Two different fast-responding aerosol instruments were employed: an ultra-fine condensation particle counter (CPC) that detects aerosols with a radius above ca. 1.5 nm and a compact lightweight aerosol spectrometer probe (CLASP) that provides a size distribution between ca. 0.1 and 6 µm. The measured sea spray emission fluxes essentially all originated from the shallow waters upwind, rather than from the surf zone/shore break. Fluxes from the CPC and from the CLASP (integrated over all sizes) were generally comparable, implying a reasonable closure in the aerosol number flux. Compared to most previous observations over the open ocean, at the same wind speed the mean sea spray number fluxes at PPAO are much greater. Significant wave height and wave Reynolds numbers explain more variability in sea spray fluxes than wind speed does, implying that enhanced wave breaking resulting from shoaling in shallow coastal waters is a dominant control on sea spray emission. Comparisons between two different wind sectors (open water vs. fetch-limited Plymouth Sound) and between two sets of sea states (growing vs. falling seas) further confirm the importance of wave characteristics on sea spray fluxes. These results suggest that spatial variability in wave characteristics need to be taken into account in predictions of coastal sea spray productions and also aerosol loading.
Highlights
Sea spray aerosols formed from wave breaking impacting the Earth’s radiative balance both directly by scattering light (Haywood et al, 1999; Lewis and Schwartz, 2004) and indirectly by affecting marine cloud formation (Clarke et al, 2006)
We examine how sea spray fluxes vary with wind speed (1–21 m s−1), significant wave height (0.2–3.1 m), wave Reynolds number (7 × 103–2 × 106) and other surface ocean parameters
Eddy covariance measurements of sea spray fluxes originating from the shallow waters upwind of Point Atmospheric Observatory (PPAO) show that about 70 % of the total detected number fluxes were submicron
Summary
Sea spray aerosols formed from wave breaking impacting the Earth’s radiative balance both directly by scattering light (Haywood et al, 1999; Lewis and Schwartz, 2004) and indirectly by affecting marine cloud formation (Clarke et al, 2006). Based on data from an Arctic cruise, Nilsson et al (2001) published the first EC measurements of aerosol number fluxes, which correlated strongly with wind speed Their data suggest that sea spray source flux consists of a film drop mode centred at a ∼ 50 nm radius and a jet-drop-mode centre at a 500 nm radius. Norris et al (2008) measured size-distributed aerosol fluxes between 0.15 and 3.5 μm radius at the Duck Pier on the east coast of the United States They showed that sea spray flux increases with the local wind speed up to a radius of 1 μm. More recently Norris et al (2012, 2013b) measured size-distributed sea spray fluxes (0.18 < radius < 6.61 μm) over the open ocean, and they explored the wind speed and wave Reynolds number dependences of the flux. We examine the size distribution and closure in aerosol number fluxes at different sea states
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
