Abstract. Synthetic Aperture Radar (SAR) images from ERS-1 have been used to study the characteristics of internal waves northeast and south of Taiwan in the East China Sea, and east of Hainan Island in the South China Sea. Rank-ordered packets of internal solitons propagating shoreward from the edge of the continental shelf were observed in the SAR images. On the basis of the assumption of a semidiurnal tidal origin, the wave speed can be estimated and is consistent with the internal wave theory. By using the SAR images and hydrographic data, internal waves of elevation have been identified in shallow water by a thicker mixed layer as compared with the bottom layer on the continental shelf. The generation mechanism includes the influences of the tide and the Kuroshio intrusion

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Synthetic aperture radar (SAR) sensors aboard polar-orbiting satellites have the abilities to acquire high spatial resolution images of the Earth's surface under all weather conditions, but their temporal sampling intervals are long. However, currently two SAR sensors aboard the European remote sensing satellite-2 (ERS-2) and the environment satellite (ENVISAT) have almost the same flight paths with ERS-2 following ENVISAT by approximately 28 minutes. Thus, high spatial resolution images from these two SAR can be jointly used to achieve a high temporal sampling interval for ocean feature monitoring and tracking. This approach has been used to track internal wave refraction along Dong-Sha Atoll in the South China Sea (SCS) on 16 April 2003. On that same day, the moderate resolution imaging spectro-radiometer (MODIS) aboard Terra passed though the same location 28 minutes after ERS-2 and collected data under almost no cloud condition. Therefore, Terra MODIS images provide another source for monitoring the wave refraction and validating the internal wave speed around Dong-Sha Atoll.

Specially designed arrays of strong‐motion seismographs near to the earthquake source are required for seismological and engineering studies of the generation and near‐field properties of seismic waves. The first such large digital array, called SMART 1 (with radius 2 km and 37 accelerometers), to record substantial ground motion (up to 0·24g horizontal acceleration) became operational in late 1980 in a highly seismic region of Taiwan. During the first 6 months of operation, SMART 1 recorded nine earthquakes with magnitudes ranging from ML 3·8 to 6·9. Three were located directly below the array at focal depths of 59 to 76 km. The remaining six had shallow depths and epicentral distances from 7 to 193 km. Digital records from 27 three‐component accelerographs were obtained from a magnitude 6·9 (ML) local earthquake on 29 January 1981. Representative measurements are described of seismic wave coherency and power spectrum as a function of wave number, frequency, azimuth of propagation and wave type. Acceleration waveforms varied significantly across the array for each event. On average, peak acceleration of horizontal components was about three times that of the vertical component. Relative spectral changes from earthquake to earthquake were large.

Spratly Islands, located in the southern part of the South China Sea (SCS), consist of more than 100 small islands, coral reefs and banks. Remote sensing is the only way to obtain a synoptic view of all of the islands in such a large area. It has been demonstrated that satellite synthetic aperture radar (SAR) imagery is a very powerful tool for monitoring meso-scale and small-scale ocean processes in a large area. In this study, satellite SAR images were used to study the ocean environment in the area of Spratly Islands. The aim was to understand the capability of satellite remote sensing to monitor ocean processes and provide information for future field studies. Two sets of high-resolution European Remote Sensing satellite (ERS)-2 SAR images over the entire Spratly Islands area were collected in April and December 2005. The ocean features were identified/extracted from the SAR images to overlay the bathymetric map for comparison. Some case studies of SAR mapping on Spratly Islands are described and issues regarding existing navigation charts are discussed.