1. An irregularly shaped warm eddy observed by Chinese underwater gliders
- Author
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Lian Shu-min, Qiu Chunhua, Yu Jiancheng, Su Danyi, Wang Yanhui, and Mao Huabin
- Subjects
010504 meteorology & atmospheric sciences ,Eddy structure ,010505 oceanography ,Underwater glider ,Ocean current ,Glider ,Radius ,Oceanography ,Atmospheric sciences ,01 natural sciences ,Current (stream) ,Tangential velocity ,Geostrophic wind ,Geology ,0105 earth and related environmental sciences - 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.
- Published
- 2018