Chapter 7 Ocean Surface Waves

Abstract

Ocean surface waves provide the most spectacular manifestation of the sea state. They reflect the local weather conditions under which they are developing and also the conditions from other locations at an earlier time. Ocean waves can be classified according to scale, in terms of their characteristic wavelengths and periods. This chapter discusses the use of altimeter data in conjunction with wind/wave models followed by their use in large-scale studies of wave climate. Satellite radar altimeters provide an estimate of significant wave height (SWH) by measuring the slope of the return pulse leading edge. Altimeters provide an estimate of the ocean surface wind speed through the measurement of the radar cross section. Another valuable application for altimeter data follows from their ability to measure the sea-state and the surface wind speed generated by tropical cyclones. The altimeter wave data have also allowed the construction of the first global wave climatologies based on measurements rather than models. The analyses of these data have provided new insights into the nature of wave climate, demonstrating convincingly that large-scale wave climate is highly variable on inter- and intra-annual time scales and providing a tool whereby this variability can be characterized and understood.