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Ten years ago, de Loor and co-workers at TNO, The Netherlands, were
the first to report bottom topography patterns in real aperture
radar (RAR) images of the southern North Sea. At that time, this
was a real puzzle. The skin depth of microwaves for sea water is
only of the order of centimeters while the sea bottom is about 20
meters below the surface. Electromagnetic radiation therefore
cannot probe the bottom directly. Similar phenomena were found in
radar imagery from SEASAT and SIR-AlB synthetic aperture radars
(SAR's) of Nantucket Shoals, the English Channel and many other
coastal areas. Since then theory and ocean field experiments (Le.,
Phelps Bank, Georgia Straits, SARSEX, TOWARD, FASINEX, etc.) have
advanced our understanding considerably. We now know that these
surface signatures are the results of surface currents, perturbed
by the bottom topography, which refract the propagation and
modulate the energy of (short) surface waves so as to cause
microwave backscatter power variations. Hence, any large scale
ocean features containing nonuniform surface currents (i.e.
internal waves, eddies, fronts, etc.) will cause similar
manifestations in the radar imagery by means of
current-wave-microwave interactions. Observations confirm this.
Ten years ago, de Loor and co-workers at TNO, The Netherlands, were
the first to report bottom topography patterns in real aperture
radar (RAR) images of the southern North Sea. At that time, this
was a real puzzle. The skin depth of microwaves for sea water is
only of the order of centimeters while the sea bottom is about 20
meters below the surface. Electromagnetic radiation therefore
cannot probe the bottom directly. Similar phenomena were found in
radar imagery from SEASAT and SIR-AlB synthetic aperture radars
(SAR's) of Nantucket Shoals, the English Channel and many other
coastal areas. Since then theory and ocean field experiments (Le.,
Phelps Bank, Georgia Straits, SARSEX, TOWARD, FASINEX, etc.) have
advanced our understanding considerably. We now know that these
surface signatures are the results of surface currents, perturbed
by the bottom topography, which refract the propagation and
modulate the energy of (short) surface waves so as to cause
microwave backscatter power variations. Hence, any large scale
ocean features containing nonuniform surface currents (i.e.
internal waves, eddies, fronts, etc.) will cause similar
manifestations in the radar imagery by means of
current-wave-microwave interactions. Observations confirm this.
This book addresses both fundamental and applied aspects of ocean waves including the use of wave observations made from satellites. More specifically it describes the WAM model, its scientific basis, its actual implementation, and its many applications. The three sections of the volume describe the basic statistical theory and the relevant physical processes; the numerical model and its global and regional applications; and satellite observations, their interpretation and use in data assimilation.
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