*2.1. Field Measurements*

The shipboard observations were obtained near the continental shelf break to the northeast of Dong-Sha Atoll, during 21–22 May 2011 (Figure 1). The research vessel collected temperature, conductivity, and depth (CTD) measurements with a Sea-Bird SBE-911 and velocity, echo amplitude with a hull-mounted 75 kHz Teledyne RDI Acoustic Doppler Current Profiler (ADCP). The ADCP vertical resolution was 16 m over a depth range from 25 m to about 650 m. The temporal resolution was 2 s, recording ensemble averages every minute, suitable to sample the ISW with the period in the order of 10 min. Several ISWs were captured during this cruise. This paper focuses on an ISW with an extreme velocity captured on 22 May that was selected for extensive discussion.
