Demonstration of the refined three-dimensional structure of mesoscale eddies and computational error estimates via Lagrangian analysis
Tóm tắt
In previous studies, Lagrangian analyses were used to assess large-scale ocean circulation, and the Lagrangian coherent structure could also reveal the evolution of the two-dimensional structure of the mesoscale eddies. However, few studies have demonstrated the three-dimensional structure of the mesoscale eddies via Lagrangian analysis. Compared with previous studies, which investigated the eddy structure via a Eulerian view, we used a Lagrangian view to provide a different perspective to study the eddy structure. An idealized cyclonic mesoscale eddy is built up over a seamount, and it presents downwelling inside the eddy and upwelling alongside the eddy formed within a closed circulation system. This structure is difficult to display via a Eulerian analysis. However, the trajectories of particles can well demonstrate the full cycle: the fluid sank and rotated inside the eddies, converged to the upwelling zone of the bottom layer and returned to the surface through upwelling. We also applied a Lagrangian analysis to a realistic simulation. As a significant phenomenon in the South China Sea, the dipole structure of the anticyclonic eddy (AE)/cyclonic eddy (CE) pair off of central Vietnam has been well studied but mainly at the sea surface. With a Lagrangian analysis, we illustrate the three-dimensional structure of the eddy pair: the fluid sank (rose) and rotated inside the AE (CE). More importantly, the trajectories of the particles suggested that there was no fluid exchange between the two eddies since the strong boundary jet separates them from each other. All the conclusions above have been verified and are supported by the computational error estimate. With a selected time step and integral period, the computational errors always present small values, although they increase with strong divergent and vertical diffusive flow.
Tài liệu tham khảo
Adams K A, Hosegood P, Taylor J R, et al. 2017. Frontal circulation and submesoscale variability during the formation of a southern ocean mesoscale eddy. Journal of Physical Oceanography, 47(7): 1737–1753, doi: https://doi.org/10.1175/JPO-D-16-0266.1
Chu Xiaoqing, Xue Huijie, Qi Yiquan, et al. 2014. An exceptional anti-cyclonic eddy in the South China Sea in 2010. Journal of Geophysical Research: Oceans, 119(2): 881–896, doi: https://doi.org/10.1002/2013JC009314
Dai Haijin, Cui Jian, Yu Jingping. 2017. Revisiting mesoscale eddy genesis mechanism of nonlinear advection in a marginal ice zone. Acta Oceanologica Sinica, 36(11): 14–20, doi: https://doi.org/10.1007/s13131-017-1134-8
Dong Changming, Lin Xiayan, Liu Yu, et al. 2012. Three-dimensional oceanic eddy analysis in the Southern California Bight from a numerical product. Journal of Geophysical Research: Oceans, 117(C7): C00H14
Döös K, Nycander J, Coward A C. 2008. Lagrangian decomposition of the Deacon Cell. Journal of Geophysical Research: Oceans, 113(C7): C07028
Fang Wendong, Fang Guohong, Shi Ping, et al. 2002. Seasonal structures of upper layer circulation in the southern South China Sea from in situ observations. Journal of Geophysical Research: Oceans, 107(C11): 3202
Gula J, Molemaker M J, McWilliams J C. 2015. Topographic vorticity generation, submesoscale instability and vortex street formation in the Gulf Stream. Geophysical Research Letters, 42(10): 4054–4062, doi: https://doi.org/10.1002/2015GL063731
Gula J, Molemaker M J, McWilliams J C. 2016. Topographic generation of submesoscale centrifugal instability and energy dissipation. Nature Communications, 7: 12811, doi: https://doi.org/10.1038/ncomms12811
Häkkinen S. 1986. Coupled ice-ocean dynamics in the marginal ice zones: Upwelling/downwelling and eddy generation. Journal of Geophysical Research: Oceans, 91(C1): 819–832, doi: https://doi.org/10.1029/JC091iC01p00819
Johannessen J A, Johannessen O M, Svendsen E, et al. 1987. Mesoscale eddies in the Fram Strait marginal ice zone during the 1983 and 1984 Marginal Ice Zone Experiments. Journal of Geophysical Research: Oceans, 92(C7): 6754–6772, doi: https://doi.org/10.1029/JC092iC07p06754
Kjellsson J, Döös K. 2012. Lagrangian decomposition of the Hadley and Ferrel cells. Geophysical Research Letters, 39(15): L15807
Kuo N J, Zheng Quanan, Ho C R. 2000. Satellite observation of upwelling along the western coast of the South China Sea. Remote Sensing of Environment, 74(3): 463–470, doi: https://doi.org/10.1016/S0034-4257(00)00138-3
Lemariè F, Kurian J, Shchepetkin A F, et al. 2012. Are there inescapable issues prohibiting the use of terrain-following coordinates in climate models?. Ocean Modelling, 42: 57–79, doi: https://doi.org/10.1016/j.ocemod.2011.11.007
Lin Xiayan, Dong Changming, Chen Dake. 2018. Cross-basin particle transport by a warm eddy southwest of Taiwan Island. Journal of Tropical Oceanography (in Chinese), 37(3): 9–18
Liu A K, Häkkinen S, Peng C Y. 1993. Wave effects on ocean-ice interaction in the marginal ice zone. Journal of Geophysical Research: Oceans, 98(C6): 10025–10036, doi: https://doi.org/10.1029/93JC00653
Manucharyan G E, Timmermans M L. 2013. Generation and separation of mesoscale eddies from surface ocean fronts. Journal of Physical Oceanography, 43(12): 2545–2562, doi: https://doi.org/10.1175/JPO-D-13-094.1
Manucharyan G E, Thompson A F. 2017. Submesoscale sea ice-ocean interactions in Marginal Ice Zones. Journal of Geophysical Research: Oceans, 122(12): 9455–9475, doi: https://doi.org/10.1002/2017JC012895
McWilliams J C. 2016. Submesoscale currents in the ocean. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 472(2189): 20160117, doi: https://doi.org/10.1098/rspa.2016.0117
Moore A M, Arango H G, Broquet G, et al. 2011. The Regional Ocean Modeling System (ROMS) 4-dimensional variational data assimilation systems: Part III-Observation impact and observation sensitivity in the California Current System. Progress in Oceanography, 91(1): 74–94, doi: https://doi.org/10.1016/j.pocean.2011.05.005
Nakamura T, Matthews J P, Awaji T, et al. 2012. Submesoscale eddies near the Kuril Straits: Asymmetric generation of clockwise and counterclockwise eddies by barotropic tidal flow. Journal of Geophysical Research: Oceans, 117(C12): C12014
Nencioli Francesco, Dong Changming, Dickey Tommy, et al. 2010. A Vector Geometry-Based Eddy Detection Algorithm and Its Application to a High-Resolution Numerical Model Product and High-Frequency Radar Surface Velocities in the Southern California Bight. Journal of Atmospheric and Oceanic Technology, 27(3): 564–579, doi: https://doi.org/10.1175/2009JTECHO725.1
Okubo A. 1970. Horizontal dispersion of floatable particles in the vicinity of velocity singularities such as convergences. Deep Sea Research and Oceanographic Abstracts, 17(3): 445–454, doi: https://doi.org/10.1016/0011-7471(70)90059-8
Shchepetkin A F, McWilliams J C. 2005. The Regional Oceanic Modeling System (ROMS): A split-explicit, free-surface, topography-following-coordinate oceanic model. Ocean Modelling, 9(4): 347–404, doi: https://doi.org/10.1016/j.ocemod.2004.08.002
Torres T S, Klein P, Menemenlis D, et al. 2018. Partitioning ocean motions into balanced motions and internal gravity waves: a modeling study in anticipation of future Space missions. Journal of Geophysical Research: Oceans, 123(11): 8084–8105, doi: https://doi.org/10.1029/2018JC014438
van Sebille E, Griffies S M, Abernathey R, et al. 2018. Lagrangian ocean analysis: Fundamentals and practices. Ocean Modelling, 121: 49–75, doi: https://doi.org/10.1016/j.ocemod.2017.11.008
Wang Guihua, Chen Dake, Su Jilan. 2006. Generation and life cycle of the dipole in the South China Sea summer circulation. Journal of Geophysical Research: Oceans, 111(C6): C06002
Weiss J. 1991. The dynamics of enstrophy transfer in two-dimensional hydrodynamics. Physica D: Nonlinear Phenomena, 48(2–3): 273–294, doi: https://doi.org/10.1016/0167-2789(91)90088-Q
Xie Shangping, Xie Qiang, Wang Dongxiao, et al. 2003. Summer up-welling in the South China Sea and its role in regional climate variations. Journal of Geophysical Research: Oceans, 108(C8): 3261, doi: https://doi.org/10.1029/2003JC001867
Zhang Xueyan, Dai Haijin, Zhao Jun, et al. 2019. Generation mechanism of an observed submesoscale eddy in the Chukchi Sea. Deep Sea Research Part I: Oceanographic Research Papers, 148: 80–87, doi: https://doi.org/10.1016/j.dsr.2019.04.015