Orbital Motion of Surface Due to Waves
Wave motion causes the particles that make up the water surface to move in an orbital motion.
· Near the wave crest, these particles move in the direction of wave propagation.
· In the troughs they move in the opposite direction.
Most of the atmospheric stress is transferred to waves with much shorter wavelengths than the dominant waves.
· Due to flow separation, more of this interaction takes place near the crests of the dominant wave, rather than in the troughs.
· The orbital motion of the dominant waves (among others) alters the velocity frame of reference of the short waves.
· Altering the velocity frame of reference is similar to an exponential change in roughness length!
· BVW model considers this simplified wave-wave interaction for stress related to capillary waves.
· The data required to determine if this process could account for variability in Charnock's constant are not yet available.
· The impact of stresses related to capillary waves is in agreement with the observations of Donelan et al. (1997).