Inferring internal wave phase speed from multi-satellite observations

The spatial and temporal variability of internal solitary waves (ISWs) speed around Dongsha Atoll in the South China Sea (SCS) was investigated using multi-satellite image pairs separated by about 0.5-2.5 hours. SAR image pair, VIIRS/MODIS and SAR/MODIS pairs in July 2007, March 2009, and May 2013 were analyzed, respectively. 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 Taylor-Goldstein (T-G) equation with a non-linear term. The ISW phase speed decreases from east to west and from south to north. The temporal variability of ISW phase speeds are mainly affected by water depth, with minor seasonal variations.