The Characters Of Internal Solitary Waves And Internal Tides In WenChang

A field program to measure the internal wave characteristics was undertaken in April to October 2005 at Wen Chang by Institute of Oceanology, Chinese Academic of Science. After analyzing the jaw data collecting from the observation program, we can conclude several element characters of internal waves in this area. First of all, the appearance of internal solitary waves there is frequent. Between the period of observation, we found 149 solitary waves and the frequency of appearance of internal solitary waves is 0.94 per day. The most common amplitude of these internal solitary waves is 32 m, and the most common period is 20 min. 80 percent of these internal solitary waves which had period from 13 min to 32 min, and amplitude from 16 m to 46 m, had a random distribution and there is no a remarkable relationship between their period and amplitude. But the amplitude of these internal solitary waves had notable change with the seasons. In the April to June, the internal solitary waves appeared frequently and had a strong amplitude which were always above 35 m; in the July to September, there were less internal solitary waves and their amplitude were smaller. Secondly, the dominate frequency of internal tides there is diurnal, which were the same as the barotropic tides there. We observed the baroclinic tides everyday, and them also changed with the seasons. The internal tides had the smallest amplitude in July. Thirdly, the current speed induced by internal waves changed with seasons. In April, the speed was high reaching 2 m per second, and the highest current speed appeared near the bottom of the sea. In the summer especially in August and September, the current speed was not notable strong as the current speed in April and May and the current speed both near the surface and bottom, had the same scale. Finally, the progress direction of internal wave there always changed. In April and May, the progress direction was parallel with isobaths of sea, but in the last period of the observation, the progress direction was always vertical with the isobaths.