Preprints
https://doi.org/10.5194/os-2021-29
https://doi.org/10.5194/os-2021-29

  23 Apr 2021

23 Apr 2021

Review status: this preprint was under review for the journal OS but the revision was not accepted.

The inference of internal solitary waves in the northern South China Sea from data acquired by underwater gliders

Wei Ma1,2, Hongwei Zhang1, Chenyi Luo1, Yanhui Wang1,2, and Yang Song1 Wei Ma et al.
  • 1Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, School of Mechanical Engineering, Tianjin University, Tianjin, China
  • 2Joint Laboratory of Ocean Observation and Exploration, Pilot National Laboratory for Marine Science and Technology, Qingdao, Shandong, China

Abstract. Internal solitary waves (ISWs) are typical large-amplitude nonlinear waves occurring in stratified oceans. The in situ observations of ISWs are needed to improve the regimes of nonlinear internal wave theories. There is violent mixing of water mass in the horizontal and vertical directions during the propagation of ISWs, which generally lasts for a short period at a fixed position. However, an underwater glider, with the features of low-speed and sawtooth motion, cannot obtain a complete thermohaline stratification before and after the ISWs arrival. Those thermohaline data collected in situ by gliders, which vary synchronously at spatial-temporal scales, raise challenges for identifying the ISWs. Four Petrel-II gliders are deployed in the active region of ISWs in the South China Sea. This paper estimates vertical water velocity from glider flight data and kinematic model, analyzes the sensitivity of parameters in the glider kinematic model, and adopts a standard nonlinear search method to calibrate the parameters insensitive to the vertical velocity. The depth-keeping experiment is performed to verify the effectiveness of the optimized results. The standard deviation of vertical water velocity in the eastern Dongsha Atoll is revealed, and its distribution indirectly reflects that the strength of vertical water activity increases gradually at the same latitude along the east-west direction. Using observations of vertical water velocity fluctuations and isothermal surface vertical displacements, single- and multiple-wave packets can be identified. The availability of this method is tested by comparison with a MODIS image. Such an analysis provides a basis for the application of glider in the observation of ISWs.

Wei Ma et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on os-2021-29', Anonymous Referee #1, 08 Jun 2021
    • AC1: 'Reply on RC1', wei ma, 09 Aug 2021
  • RC2: 'Comment on os-2021-29', Anonymous Referee #2, 25 Jun 2021
    • AC2: 'Reply on RC2', wei ma, 09 Aug 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on os-2021-29', Anonymous Referee #1, 08 Jun 2021
    • AC1: 'Reply on RC1', wei ma, 09 Aug 2021
  • RC2: 'Comment on os-2021-29', Anonymous Referee #2, 25 Jun 2021
    • AC2: 'Reply on RC2', wei ma, 09 Aug 2021

Wei Ma et al.

Wei Ma et al.

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Short summary
We conducted internal solitary waves(ISWs) observation in the northern South China Sea in August 2017 by the four Petrel-Ⅱ gliders. The gliders capture the internal waves, and the types of internal waves are classified by vertical water velocities inferred from glider and hydrographic data. Combined with the analysis of a MODIS true color image, we verify this method. The observation of different types of ISWs in South China Sea is the application of underwater gliders for the first time.