Water characteristics of abyssal and hadal zones in the southern Yap Trench observed with the submersible Jiaolong -- Journal of Oceanology and Limnology,2020,38(3):593-605

	Cite this paper:
	LIU Xuehai, LIU Yongzhi, CAO Wei, SUN Chengjun. Water characteristics of abyssal and hadal zones in the southern Yap Trench observed with the submersible Jiaolong[J]. Journal of Oceanology and Limnology, 2020, 38(3): 593-605

Water characteristics of abyssal and hadal zones in the southern Yap Trench observed with the submersible Jiaolong

LIU Xuehai^1,2,3, LIU Yongzhi^1,2,3, CAO Wei¹, SUN Chengjun¹

1 First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China;
2 Laboratory for Regional Oceanography and Numerical Modeling, Pilot National Laboratory for Marine Science and Technology(Qingdao), Qingdao 266237, China;
3 Key Laboratory of Marine Science and Numerical Modeling, Ministry of Natural Resources, Qingdao 266061, China

Abstract:

Using observations in an applied cruise of the submersible Jiaolong, water characteristics, geostrophic transport, and turbulent mixing in abyssal and hadal zones of the southern Yap Trench were studied. The spatial structures of deep water show that the abyssal water is cold, saline, and oxygen rich. The hadal water has very small changes in potential temperature and potential density, and a little decrease in salinity and obvious decrease in oxygen. The isotherm, isopycnal, and isohaline are depressed in abyss over the central trench. The turbulent mixing is enhanced in the near-bottom zone and the hadal water on the trench slope, especially at the steep slope, the dissipation rate and diffusivity is strong, which weakens the stratification. The geostrophic flows move southward in the western region of the trench and northward in the eastern region, indicating cyclonic circulation. In the central region of the trench, the water transport is ~1.74 Sv southward. In the hadal zone, the northward and southward transports are balanced. Our analysis suggests that the abyssal water in the southern Yap Trench is from Lower Circumpolar Water (LCPW) and the hadal water seems to be of the isolated local water rather than LCPW.

Key words: Yap Trench|abyssal and hadal|the submersible Jiaolong|diapycnal mixing|geostrophic flows

Received: 2018-12-27 Revised: 2019-02-20

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