www.postersession.com The refraction and reconnection of internal solitary waves (ISWs) around the Dongsha Atoll (DSA) in the northern South China Sea (SCS) are investigated based on SAR observations and numerical simulations. In general, a long ISW front refracts and splits into northern and southern branches when it passes the DSA. In this study, the statistics of Envisat ASAR images show that the two wave branches can reconnect behind the DSA (Figure 1), but the reconnection location varies. Methods Conclusions Study on internal waves at Dongsha Atoll Tong Jia, Xiao-Ming Li, Jiangjun Liang, Jin Sha Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences Abstract Relative to the extension line of Dongsha Island, the reconnection of ISW branches can be categorized into the west (Figure 2a), northwest (Figure 2b), southwest (Figure 2c) of Dongsha Island. Besides, there are other ISWs which still separate from each other behind the DSA (Figure 2d). The results of E1 prove the validity of the NRM model around the DSA. Experiments E2-E9 show that ocean stratification, background currents, and initial wave amplitude all affect the phase speeds of ISW branches and therefore shift their reconnection locations while initial wave fronts profoundly influence the subsequent propagation paths. Envisat ASAR TerraSAR-X SAR Observations of ISW Reconnection Behind the DSA Reference Experiment Based on the TSX Observations by NRM Sensitivity Experiments of Changing Model parameters NRM HYCOM/NCODA Ocean Stratification Background Current Results and analyses Variations of reconnection location Reference Experiment(E1) Reference experiemnt Initial Wave Amplitude Initial Wave fronts NRM Comparisons and analyses Sensitivity Experiments(E2-E9) SAR Statistics Statistical classification change Research Method Figure 1. The propagation of ISWs near the DSA (Hsu and Liu,2000) References Hsu, M. K., & Liu, A. K. (2000). Nonlinear internal waves in the South China Sea. Canadian Journal of Remote Sensing, 26(2), 72–81. Xie, J., He, Y., Lü , H., Chen, Z., Xu, J., & Cai, S. (2016). Distortion and broadening of internal solitary wavefront in the northeastern South China Sea deep basin. Geophysical Research Letters, 43(14). Objective With the help of SAR data and a nonlinear refraction model (NRM) which is developed by Xie et al. (2016), this study aims to clarify the variation in reconnection locations of ISWs downstream of the DSA and reveals the mechanisms governing the reconnection process of ISWs near the DSA. Figure 4. Results of a reference experiment and other eight sensitivity experiments E1:reference experiment E2:using seasonal summer stratification E3:eastward current velocity +0.2m/s E4:eastward current velocity -0.1m/s E5:initial amplitude +10% E6:initial amplitude +20% E7:initial wave fronts observed on 03/27/2005 ASAR image E8:initial wave fronts observed on 08/27/2008 ASAR image E9:initial wave fronts observed on 06/20/2004 ASAR image Figure 2. The spatial variations of reconnection or separation of ISWs behind the DSA Figure 3. Two consecutive TSX images within 12 h used in E1 Based on the first realistic simulation whose results agree well with the consecutive TerraSAR-X (TSX) images captured within 12 h of each other, eight sensitivity simulations are conducted and show that ocean stratification, background currents, and initial wave amplitudes all affect the phase speeds of wave branches and therefore shift their reconnection locations while shapes and locations of incoming wave branches upstream of the DSA profoundly influence the subsequent propagation paths. Results The results of this study are shown in Figure 2 and Figure 4. Figure 3 presents the SAR images used in E1.