A Global View of Swell and Wind Sea Climate in the Ocean by Satellite Altimeter and Scatterometer

Abstract

Numerous case reports and regional studies on swell and wind sea events have been documented during the past century. The global picture of these common oceanic phenomena, however, is still incomplete in many aspects. This paper presents a feasibility study of using collocated wind speed and significant wave height measurements from simultaneous satellite scatterometer and altimeter sources to observe the spatial and seasonal pattern of dominant swell and wind wave zones in the world's oceans. Two energy-related normalized indices are proposed, on the basis of which global statistics of swell/wind sea probabilities and intensities are obtained. It is found that three well-defined tongue-shaped zones of swell dominance, termed ?swell pools,? are located in the eastern tropical areas of the Pacific, the Atlantic, and the Indian Oceans, respectively. Regions of intensive wave growth are observed in the northwest Pacific, the northwest Atlantic, the Southern Ocean, and the Mediterranean Sea. Seasonality is distinct for the climate of both swell and wind sea, notably the large-scale northward bending of the swell pools in boreal summer, and the dramatic shift of wave-growing extent from a summer low to an autumn high. The results of this study may serve as a useful reference for a variety of activities, such as ocean wave modeling, satellite algorithm validation, coastal engineering, and ship routing, when information on swell and wind sea conditions is needed.