Atmospheric and Climate Sciences > Vol.5 No.3, July 2015

José Augusto P. Veiga^1*, Mônica R. Queiroz²

¹Department of Meteorology, Institute of Technology, Amazonas State University, Manaus, Brazil.
²UNINORTE Laureate International Universities, Manaus, Brazil.

In this study the effect of the surface waves over sea surface roughness (z₀) and drag coefficient (C_D) is investigated by combining an ocean wave model and a simplified algorithm, which estimates z₀ and C_D with and without dependence on the sea state. This investigation was possible from several numerical simulations with the Wave-Watch-III (WW3) model for complex wind conditions. The numerical experiments were performed for idealized like-hurricanes with different translation speed (0, 5 and 10 m/s) and maximum wind speed (MWS) at the centre (35, 45 and 55 m/s). It is observed that z₀ and C_D are strongly dependent on the sea state, via substantial modification in Charnock parameterization (z_ch). As the hurricane translation speed increases more discrepancies in z₀ and C_D are observed in opposite quadrants around the region of MWS. As for instance, higher, longer and older (or more developed) waves, located in the front-right quadrant, produce lower values of z₀ and C_D. In the rear-left quadrant, where the waves are lower, shorter and younger (or less developed), higher values of z₀ and C_D are observed. In addition the difference between values on opposite quadrants increases as the hurricane intensity increases, showing the hurricane intensification dependence. Interesting aspects are observed in scatter plotting wave age versus Charnock coefficient. It is also observed that z_ch, which has a constant value of 0.0185, is modified by the sea state, where young waves produce higher values of z_ch, while old waves are related to lower values of z_ch when compared with z_ch without dependence on sea state.

Wave Prediction, Surface Gravity Waves, Hurricane Translation Speed

Veiga, J. and Queiroz, M. (2015) Impact of the Waves on the Sea Surface Roughness Length under Idealized Like-Hurricane Wind Conditions (Part II). Atmospheric and Climate Sciences, 5, 326-335. doi: 10.4236/acs.2015.53025.