Sea-spray aerosol particles generated in the surf zone

Abstract

[1] To assess the properties of aerosol particles generated over the surf zone, two experiments were held at the pier of Scripps Institution of Oceanography (SIO), La Jolla CA, and at the pier of the U.S. Army Corps of Engineers Field Research Facility (FRF) in Duck NC. On both sites concentrations of surf-generated sea spray particles, wave parameters and meteorological conditions were measured. The surf-aerosol concentrations in the diameter range 0.2-10 microns were obtained from the difference in aerosol size distributions measured upwind and downwind of the surf zone. It was found that the flux of surf-generated particles at diameters at formation can be expressed in terms of wave energy dissipation, which itself is related to the properties of the incoming wavefield and the bathymetry of the beach. Although the flux can also be modeled in terms of wind speed, this relation is considered to be not universal and limited to low-to medium wind speeds. In Duck NC, two transport experiments were performed under offshore flow conditions. In this case, the surf-aerosol concentrations were obtained from the differences in three aerosol size distributions, measured just before and just behind the surf zone and up to 16 km downwind (out to sea). No significant decrease in concentration was observed at the farthest range, which suggests that an appreciable amount of surf-generated aerosols is advected over tens of kilometers.

Investigating Source Contributions of Size‐Aggregated Aerosols Collected in Southern Ocean and Baring Head, New Zealand Using Sulfur Isotopes

“…Our observed SO 4 2− SS concentrations only showed a weak correlation with the average wind speed ( P > 0.05, R 2 = 0.03, Figure e) similar to other field studies (Ghahremaninezhad et al, ; Jaeglé et al, ; Lewis & Schwartz, ; Rempillo et al, ; Seguin et al, ). In contrast, maximums in wave peak heights usually corresponded to high SO 4 2− SS concentrations at Baring Head (Figure e), supporting the hypothesis that breaking waves increase sea‐salt aerosol formation near the coast (Jensen et al, ; Monahan et al, ; Van Eijk et al, ). Therefore, we suggest that wave height was more important than wind speed, under low median wind speeds (9.9 ± 3.9 m/s), in generating sea‐salt aerosols at Baring Head during the study period.…”

“…2À SS concentrations at Baring Head (Figure 2e), supporting the hypothesis that breaking waves increase sea-salt aerosol formation near the coast (Jensen et al, 1997;Monahan et al, 1986;Van Eijk et al, 2011). Therefore, we suggest that wave height was more important than wind speed, under low median wind speeds (9.9 ± 3.9 m/s), in generating sea-salt aerosols at Baring Head during the study period.…”

The surf zone heat budget: The effect of wave heating

“…During different seasons or at other locations (such as the Oregon coast where there are strong waves and cloudy skies), the wave energy flux F wave may be even more important in the surf zone heat budget. Assuming a planar beach slope and normally incident shallow water waves Thornton and Guza, 1983], L sz = h b ∕ , and the ratio F wave ∕(Q sw L sz ), using (4), becomes…”

“…The COARE 2.5 parameterization for Q lat and Q sen used here does not include depth-limited breaking spray effects. Surf zone depth-limited wave breaking generates spray at least an order of magnitude larger than just offshore [van Eijk et al, 2011]. Thus, surf zone latent and sensible heat fluxes may be under-represented, which could result in the best fit slope above one and net cooling.…”

The Advanced Navy Aerosol Model (ANAM): validation of small-particle modes

“…Finally, a dedicated mode was added to describe the production of aerosols over the surf zone and their subsequent advection out to sea. 7 These improvements have been released in the ANAM5 series (see middle panel of Figure 1). However, these improvements do not address the contribution of non-marine aerosols.…”