Tracking the internal waves in the South China Sea with environmental satellite sun glint images

摘要

The propagation of internal solitary waves (ISWs) in the South China Sea (SCS) was tracked using National Aeronautics and Space Administration (NASA) Moderate Resolution Imaging Spectroradiometer (MODIS) and the Visible Infrared Imaging Radiometer Suite (VIIRS) sun glint image pairs. The acquisition times of the two images comprising the same pair is usually separated by about 2 hours. Four pairs of images in May and August 2013 were analysed. The ISW phase speeds were derived using the horizontal displacement of the ISW patterns and the time difference between the 2 satellite images. The phase speeds were in good agreement with the theoretical calculations using the Sturm-Louisville (S - L) equation with a non-linear term. Monthly ocean stratification data and bathymetry were used in the theoretical calculations. The ISW phase speeds are mainly affected by bottom depth, with seasonal variations. The ISWs propagated faster in August than in May. Our results also show that the ISW propagation in northern SCS can be mapped using environmental satellite sun glint images in short period of time with the advantage of large scale.