Travel time fluctuation of normal mode：AEYFI05 experiment

The acoustic data of Acoustics Experiment of Yellow sea Oceanic Front and Internal Waves (AEYFI05) are analyzed in this paper.The acoustic travel time of 1st normal mode is extracted from the experiment data.It is found that there exist "coherent high frequency fluctuations" of around 10~50 minutes in time interval and 2~10 ms in amplitude.To interpret this observation,a qualitative model of acoustic propagation through a local exciting and propagating process of shallow water internal waves is developed.The comparison of the travel time data with the in-situ temperature string data showing maximum correlation at a delayed interval about 520 min supports this model.