Simulation of Inertial Droplet Dispersion and the Spray Mediated Fluxes in the Atmospheric Boundary Layer Above Waved Water Surface: A Lagrangian Stochastic Model Versus Direct Numerical Simulation

Abstract

Lagrangian stochastic models (LSM) are widely used to model the dispersion of sea spray droplets injected from the water surface into the marine atmospheric boundary layer (MABL) and for evaluation of the spray impact on the exchange fluxes between the atmosphere and the ocean. While moving through the MABL the droplets pass through the region of high gradients of air velocity, temperature and humidity occurring in the vicinity of the air-water interface. In this case, the applicability of LSMs constructed under the assumption of weakly inhomogeneous flows is questionable. In this work, we develop a Lagrangian stochastic model taking into account the strongly inhomogeneous structure of the airflow in MABL and, in particular, the anisotropy of turbulence dissipation rate. The model constants and the diffusion matrix coefficients are calibrated by comparison of the LSM prediction for the profiles of droplet concentration and the exchange fluxes of sensible and latent heat against the results of direct numerical simulation (DNS) of turbulent, droplet-laden airflow over a waved water surface. Keywords Lagrangian stochastic model • Marine boundary layer • Sea spray droplets • Direct numerical simulation

Impact of sea spray‐mediated heat fluxes on polar low development

“…Subsequent studies by Troitskaya et al . (2018, 2016, 2023) suggest opportunities for enhancing the Andreas et al . (2015) parameterization.…”

“…Their findings indicate that bag breakup is the dominant mechanism of sea spray production in high wind conditions, a factor not accounted for adequately in the Andreas et al (2015) parameterization. Subsequent studies by Troitskaya et al (2018Troitskaya et al ( , 2016Troitskaya et al ( , 2023 suggest opportunities for enhancing the Andreas et al (2015) parameterization. However, it is crucial to note that our study does not focus on this specific aspect.…”

Drag Coefficient Parameterization under Hurricane Wind Conditions

“…To take into account the effect of spray and foam in the parameterization of drag coefficient and, subsequently, in the wave model, it is convenient to obtain a formula expression for CD. Such an expression is obtained [36] in the framework of numerical experiments with the Lagrangian stochastic model (LSM), the drag coefficient depends on 10 m wind speed and wave age parameter, and it is different for two ranges of wind speeds: Thus, the estimates allow us to conclude that it is important to take into account the effect of spray and foam in the numerical simulation wave parameters. To take into account the effect of spray and foam in the parameterization of drag coefficient and, subsequently, in the wave model, it is convenient to obtain a formula expression for C D .…”

“…To take into account the effect of spray and foam in the parameterization of drag coefficient and, subsequently, in the wave model, it is convenient to obtain a formula expression for C D . Such an expression is obtained [36] in the framework of numerical experiments with the Lagrangian stochastic model (LSM), the drag coefficient depends on 10 m wind speed and wave age parameter, and it is different for two ranges of wind speeds:…”