The effects of background current and pycnocline depth on surface signals of internal waves

The impacts of pycnocline depth and background current on surface signals of underwater internal waves in the northeastern South China Sea(SCS) were studied using four well-designed simulation experiments. The index named maximum absolute value of surface current gradient(MASCG) was used to describe the effect. Model results confirm that the synclastic background current strengthened the horizontal flow gradient of internal waves, while the opposing background current weakened the surface current gradient of internal waves. Pycnocline depth affected dramatically internal wave surface signal. A deeper pycnocline would reduce the internal waves' surface signal intensity. The quantity of surface signals from oceanic internal waves depends on marine environmental conditions and dynamical characteristics of internal waves. These results may help better understanding of internal waves from remote sensing measurements.