The seasonal variation of the North Pacific Meridional Overturning Circulation heat transport -- Journal of Oceanology and Limnology,2019,37(2):423-433

	Cite this paper:
	LIU Hongwei, ZHANG Qilong, PANG Chongguang, DUAN Yongliang, XU Jianping. The seasonal variation of the North Pacific Meridional Overturning Circulation heat transport[J]. Journal of Oceanology and Limnology, 2019, 37(2): 423-433

The seasonal variation of the North Pacific Meridional Overturning Circulation heat transport

LIU Hongwei^1,2,5, ZHANG Qilong^1,5, PANG Chongguang^1,5, DUAN Yongliang^3,4, XU Jianping²

1 Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences and Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China;
2 State Key Laboratory of Satellite Ocean Environment Dynamics, MNR, Hangzhou 310012, China;
3 Center for Ocean and Climate Research, First Institute of Oceanography, MNR, Qingdao 266061, China;
4 Laboratory for Regional Oceanography and Numerical Modeling, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China;
5 Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China

Abstract:

Based on the 50-year Simple Ocean Data Assimilation (SODA) reanalysis data, we investigated the basic characteristics and seasonal changes of the meridional heat transport carried by the North Pacific Meridional Overturning Circulation. And we also examined the dynamical and thermodynamic mechanisms responsible for these heat transport variability at the seasonal time scale. Among four cells, the tropical cell (TC) is strongest with a northward heat transport (NHT) of (1.75±0.30) PW (1 PW=1.0×10¹⁵ W) and a southward heat transport (SHT) of (-1.69±0.55) PW, the subtropical cell (STC) is second with a NHT of (0.71±0.65) PW and SHT of (-0.63±0.53) PW, the deep tropical cell (DTC) is third with a NHT of (0.18±0.03) PW and SHT of (-0.18±0.11) PW, while the subpolar cell (SPC) is weakest with a NHT of (0.09±0.05) PW and SHT of (-0.07±0.09) PW. These four cells all have different seasonal changes in their NHT and SHT. Of all, the TC has stronger change in its SHT than in its NHT, so do both the DTC and SPC, but the seasonal change in the STC SHT is weaker than that in its NHT. Therefore, their dynamical and thermodynamic mechanisms are different each other. The local zonal wind stress and net surface heat flux are mainly responsible for the seasonal changes in the TC and STC NHTs and SPC SHT, while the local thermocline circulations and sea temperature are primarily responsible for the seasonal changes of the TC, STC and DTC SHTs and SPC NHT.

Key words: meridional overturning circulation|heat transport|North Pacific|seasonal variation

Received: 2018-02-02 Revised: 2018-04-04

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