Atmospheric Sea Spray Modeling in the North-East Atlantic Ocean using Tunnel-Derived Generation Functions and the SUMOS Cruise Dataset
This study contributes to the communal effort to improve understanding of sea spray generation and transport. For the first time, laboratory-derived sea spray generation functions (SSGFs) are parameterized in the Meso-NH mesoscale atmospheric model and are field tested. Formulated from the MATE19 laboratory experiments (Bruch et al., 2021) two SSGFs are driven by the upwind component of the wave-slope variance S2x (herein B21A), or both S2x and the wind friction velocity cubed u3* (herein B21B). As part of our first attempt to incorporate the SSGFs in Meso-NH, the simulations are run without a wave model, and the wave-wind SSGFs are assumed wind-dependent. Model evaluation is achieved with sea spray and meteorological measurements acquired over the 0.1-22.75 µm radius range and 1-20 m s-1 U10 wind speeds, 15 meters above the sea surface onboard R/V Atalante during the 25 day SUMOS field campaign in the Bay of Biscay. The B21B SSGF offers particularly good sensitivity to a wide range of environmental conditions over the size range, with an average overestimation by a factor 1.5 compared with measurements, well below the deviations reported elsewhere. B21A also performs well for larger droplets at wind speeds above 15 m s-1. Associated with airflow separation and wave breaking, the wave-slope variance proves to be a key parameter for the scaling of sea spray generation. Using model outputs obtained with B21B, sea spray can be found far beyond the marine atmospheric boundary layer, with large plumes reaching 100 km inland and altitudes of 2.5 km.
Plain Language Summary
The effects of sea spray on weather and climate remain poorly understood as a result of sparse measurements and large uncertainties in the generation flux. With the aim of improving sea spray transport in atmospheric models, two sea spray generation functions derived from the MATE19 laboratory campaign are parameterized in the Meso-NH mesoscale atmospheric model. The simulations are run over the Bay of Biscay in February-March 2021, and are compared with sea spray concentrations measured during the SUMOS field campaign. Results show that the laboratory-derived generation functions allow accurate predictions of sea spray concentrations. Furthermore, simulations show that sea spray droplets can be transported far over land, and high into the atmosphere.