Long ocean surface waves influence on ocean surface roughness

Time 
01/25/2017 - 15:00-01/25/2017 - 16:30
Room 
Sasakawa Auditorium

Authors

Ali Al Sam
(Department of Energy Sciences, Lund University, Lund, Sweden)
Robert Szasz
(Department of Energy Sciences, Lund University, Lund, Sweden)
Johan Revstedt
(Department of Energy Sciences, Lund University, Lund, Sweden)

Theme

Speaker(s): 
Ali Al Sam

Weather, wave and ocean forecasts have a profound impact on maritime industry around
the world. Since the  shipping operations take place on or near the ocean surface, real time information on the sea state and on the dynamic structure of the Marine Atmospheric Boundary Layer is especially important.
Despite many experimental and theoretical studies, there are shortcomings in the current knowledge of the the wind/wave/current coupling mechanisms. Recent field observations and numerical simulations have shown that the impact of the waves, in particularly long waves, on the MABL might be stronger than previously assumed. Moreover, since the remote sensing is becoming an important tool for the maritime industry and the resolution of remote sensors is becoming comparable to the wavelength of dominant ocean surface waves, the usual assumption of homogeneous surface roughness is no longer adequate. Hence, a better understanding of the long wave effects on the MABL would provide a valuable information that can lead to improve the weather, wave and ocean forecasts.
In this study we discuss the impacts of the long ocean surface waves on the wind drag and on the ocean surface roughness. Large-Eddy Simulations are used in this study to model the atmospheric turbulence.
The surface wind velocity, turbulence intensity and wind drag modulations due to the presence of long waves and nonhomogeneous distribution of short waves will be provided. The results will be presented as a comparison between the MABL over long waves to that over short waves (calm sea).