Investigation of atmospheric gravity waves and oceanic internal waves using envisat synthetic aperture radar images

Atmospheric gravity waves (AGWs) and oceanic internal waves (OIWs) become visible on synthetic aperture radar (SAR) images acquired over the ocean because they modulate the short-scale sea surface roughness and thus the radar backscattering. The modulation patterns visible on SAR images originating from AGWs and OIWs often look quite similar. Criteria are presented how to discriminate between both types of patterns. Several examples of SAR images acquired by the Advanced Synthetic Aperture Radar (ASAR) onboard the European Envisat satellite over the South China Sea (SCS) are presented which show radar signatures of AGWs and OIWs. The SAR images yield valuable information on the characteristics of both types of waves. In particular, it is shown how SAR images can be used to provide evidence for a theory on the generation and propagation of short internal waves trailing strong internal solitary waves in the northern SCS .