Sea surface imprints of coastal mountain lee waves imaged by synthetic aperture radar

[1] A group of mountain lee waves is observed on an Envisat advanced synthetic aperture radar (SAR) image on the lee side of Mountain Laoshan (1133 m) along the Yellow Sea coast of China. The lee waves are shown as alternating bright and dark patterns on the SAR image, indicating the ocean surface wind oscillation associated with the atmospheric wavefield. The horizontal wind variation between wave crest and trough is from 7 to 17 m/s. A Moderate Resolution Imaging Spectroradiometer image acquired about 8.5 h prior to the SAR pass also showed the same group of standing lee waves. The cloud pattern matches the high-wind pattern in the SAR-derived wind image. The mesoscale Weather Research and Forecasting (WRF) model is used to simulate the lee wave phenomenon. We run the triply nested grid model with the highest horizontal resolution of 1 km. The WRF model successfully captures the characteristics of the lee wave. The waves are generated by the terrain forcing and the wave-induced perturbation propagates very strongly upward to the 500 hPa level. The event lasts about 24 h. Based on the WRF model wind results, we run a radar imaging model to simulate the SAR observation. The normalized radar cross section (NRCS) variations induced by the lee wave are compared between the radar simulation and the actual SAR observation. Reasonable agreement is reached.