Swell Wavelength Variation Across the Ocean Based on SAR Wave Mode Data

This paper presents the wavelength trend of a swell propagating across the ocean along a great circle path. Hindcast WW3 wave model data are used for finding the storm sources that are the starting points for a swell. We search the SAR swell observation sequences from ASAR wave mode Level 2P data. It is shown that the wavelength of a swell will increase when propagating from a storm source. When a swell propagates far beyond 10000 km, the wavelength may decrease because shorter wind seas are introduced by the local wind in the westerlies from the other hemisphere. The wavelength can be approximately regarded as constant beyond 4000 km from the storm source.