Influence of sea spray and rainfall on the surface wind profile during conditions of strong winds

Janin and Cermak (1988) have: determined that airborne sediment in a wind tunnel substantially alters the low-level wind profile. This material apparently causes a reduction in wind speed since the pressure gradient force must accelerate both the air and the sediment, against the force of surface shearing stress. In this brief paper, we explore whether atmospheric wind profiles would be expected to be modified during periods of high winds as a result of heavy rainfall or sea spray. Although there has been controversy regarding the effect of sediment load on pressure drop (e.g., Rangaraju, 1988), our assumption that the wind profile rem~ins logarithmic is based on the physical modeling of Janin and Cermak (1988) in which even with sand loading in the atmosphere, the square root of the total kinetic energy profile remains logarithmic. This means that a given pressure ~adient force can accelerate either air, or a combination of air and a suspended material but when suspended material is present, the actual air velocity will be less. This Note represents an extension of Janin's study of sediment to the suspension of water in the atmosphere. If the effect of the suspended water mass were significant, there could be substantial effects on the aerodynamic response of buildings and other structures in high winds.