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Journal of Oceanography

, Volume 75, Issue 2, pp 139–148 | Cite as

An irregularly shaped warm eddy observed by Chinese underwater gliders

  • Qiu Chunhua
  • Mao HuabinEmail author
  • Wang Yanhui
  • Yu Jiancheng
  • Su Danyi
  • Lian Shumin
Original Article
  • 140 Downloads

Abstract

Mesoscale eddies are important for transporting oceanic energy and matter. We investigated the three-dimensional structure of an irregularly shaped warm eddy using three Chinese underwater gliders and satellite data during May 2015 in the northern South China Sea. The warm eddy lasted for 2 months, remained quasi-steady, and had a mean radius of ~ 70 km from May 10 to May 31. The heat contents observed along the two glider tracks differed markedly, by 2 × 109 J/m2, which reflected an imbalance in the geostrophic and tangential velocity distributions of the eddy. The geostrophic/tangential velocity decreased/increased with depth within the warm eddy. The maximum tangential velocities calculated using the datasets from the two gliders were 0.8 and 0.25 m/s, respectively, confirming that the shape of the warm eddy was horizontally asymmetrical. Large errors can arise when the heat, energy, and matter transport for an irregularly shaped eddy are estimated using a regular circular model. We suggest that more intersecting glider tracks should be used to retrieve the three-dimensional eddy structure, and that those tracks should be better designed. The irregular shape of the warm eddy was likely induced by oceanic currents such as the wind-induced Ekman current. Further study is needed to elucidate the eddy–current interactions and the mechanisms thereof.

Keywords

Irregular shape Warm eddy Chinese underwater glider Oceanic current Eddy–current interaction 

Notes

Acknowledgements

This study was supported by the National Key R&D Plan of China (nos. 2017YFC0305804, 2017YFC0305904), the National Natural Science Foundation of China (41776027), the Natural Science Foundation of Guangdong Province (no. 2015A030313151), and the Distinguished Young Teachers of Fundamental Research Funds for the Central Universities (no. 17lgzd11). The glider data were provided by the State Key Laboratory of Robotics, Shenyang Institute of Automation, and Tianjin University. We are grateful for the AVISO (http://www.aviso.oceanobs.com/en/data/products/sea-surface-height-products/global/index.html) sea level anomaly data and the NCEP/NCAR (http://www.ersl.noaa.gov/psd/data/reanalysis/reanalysis.shtml) surface wind speed data. The data associated with this paper are available upon request from the first or corresponding author, with the condition that they will be used solely for scientific research.

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Copyright information

© The Oceanographic Society of Japan and Springer Japan KK, part of Springer Nature 2018

Authors and Affiliations

  • Qiu Chunhua
    • 1
    • 5
  • Mao Huabin
    • 2
    Email author
  • Wang Yanhui
    • 3
  • Yu Jiancheng
    • 4
  • Su Danyi
    • 1
  • Lian Shumin
    • 2
  1. 1.The Center for Coastal Ocean Science and Technology, School of Marine SciencesSun Yat-sen UniversityGuangzhouChina
  2. 2.State Key Laboratory of Tropical OceanographySouth China Sea Institute of Oceanology, Chinese Academy of SciencesGuangzhouChina
  3. 3.School of Mechanical EngineeringTianjin UniversityTianjinChina
  4. 4.State Key Laboratory of RoboticsShenyang Institute of Automation, Chinese Academy of SciencesShenyangChina
  5. 5.Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine SciencesSun Yat-sen UniversityGuangzhouChina

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