<p>Sea spray induced by surface wave breaking plays an important role in air-sea flux. However, large differences in sea spray generation at the same wind speed were presented in previous studies. As a result, the parameterizations of sea spray generation functions can reach 4 orders difference. Wind speed may not be enough to explain this difference, and the surface wave state is a significant factor that causes this large difference, which then affects the estimation of the air-sea heat fluxes. In this study, synchronous observations of air-sea heat fluxes, surface waves and sea spray were conducted at a tower-based platform in a coastal region. Results showed that the sea spray generation is strongly correlated with both wind speed, and wave age as previously; more importantly, wind-wave alignment angle can cause approximately 1.3 orders (or 20 times) of sea spray generation function (SSGF) difference. A new SSGF with a dimensionless parameter <i>R</i><Stack> <sub>B</sub> <sup>0.7</sup> </Stack><i>β</i><sup>-1</sup>cos<i>θ</i> was proposed. Heat fluxes caused by sea spray can be comparable to interfacial heat fluxes even at moderate wind speed. The three parameters of sea spray (<i>α</i>=6.4, <i>σ</i>=16, <i>γ</i>=6.3) were optimally fitted and evaluated. The air-sea heat flux evaluated in droplet evaporation layer (DEL) was improved with the new scheme, especially for sensible heat flux. The new parameters should be more suitable than other widely used parameters in numerical simulations.</p>

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A new sea spray generation function with wind-wave (mis)alignment

  • Zhanchi Liu,
  • Sheng Chen,
  • Hongyu Ma,
  • Wenzheng Jiang,
  • Yongqing Yu,
  • Zhanli Wang,
  • Fangli Qiao

摘要

Sea spray induced by surface wave breaking plays an important role in air-sea flux. However, large differences in sea spray generation at the same wind speed were presented in previous studies. As a result, the parameterizations of sea spray generation functions can reach 4 orders difference. Wind speed may not be enough to explain this difference, and the surface wave state is a significant factor that causes this large difference, which then affects the estimation of the air-sea heat fluxes. In this study, synchronous observations of air-sea heat fluxes, surface waves and sea spray were conducted at a tower-based platform in a coastal region. Results showed that the sea spray generation is strongly correlated with both wind speed, and wave age as previously; more importantly, wind-wave alignment angle can cause approximately 1.3 orders (or 20 times) of sea spray generation function (SSGF) difference. A new SSGF with a dimensionless parameter R B 0.7 β-1cosθ was proposed. Heat fluxes caused by sea spray can be comparable to interfacial heat fluxes even at moderate wind speed. The three parameters of sea spray (α=6.4, σ=16, γ=6.3) were optimally fitted and evaluated. The air-sea heat flux evaluated in droplet evaporation layer (DEL) was improved with the new scheme, especially for sensible heat flux. The new parameters should be more suitable than other widely used parameters in numerical simulations.