Chemistry Reference
In-Depth Information
face-active substance has a strong influence on the generation of bound
waves at the crests of the gravity waves. At intermediate wind speeds of
approximately 6 m s
-1
the X-band backscatter is mainly caused by bound
Bragg waves, and the Ka-band backscatter is caused by both bound and
freely propagating Bragg waves. In the wind speed range between 7 and
9 m s
-1
, where the short gravity waves are strongly damped by the OLA
slick, both the X- and Ka-band backscatter are caused only by freely pro-
pagating waves. This wave damping behaviour of the OLA slick can ex-
plain the strong damping of the radar backscatter in this particular wind
speed range as well as the fact that the measured wave damping exceeds
the values predicted by Marangoni damping theory for this (water wave)
frequency range.
Fig. 8.
Same as Figure 7, but for a water surface covered with oleyl alcohol
(OLA). The minimum wind speed for the excitation of ripple waves on a slick-
covered water surface is about 4.5 m s
-1
These results obtained from a slick-covered water surface are of great
importance for the interpretation of measured reductions of the radar back-
scattering by oceanic surface films (see the preceding sections). However,
we also note that results obtained from wind-wave tank experiments can-
