Abstract
Submesoscale processes in marginal seas usually have complex generating mechanisms, highly dependent on the local background flow and forcing. This numerical study investigates the spatial and seasonal differences of submesoscale activities in the upper ocean of the South China Sea (SCS) and the different dynamical regimes for sub-regions. The spatial and seasonal variations of vertical vorticity, horizontal convergence, lateral buoyancy gradient, and strain rate are analyzed to compare the submesoscale phenomenon within four sub-regions, the northern region near the Luzon Strait (R1), the middle ocean basin (R2), the western SCS (R3), and the southern SCS (R4). The results suggest that the SCS submesoscale processes are highly heterogeneous in space, with different seasonalities in each sub-region. The submesoscale activities in the northern sub-regions (R1, R2) are active in winter but weak in summer, while there appears an almost seasonal anti-phase in the western region (R3) compared to R1 and R2. Interestingly, no clear seasonality of submesoscale features is shown in the southern region (R4). Further analysis of Ertel potential vorticity reveals different generating mechanisms of submesoscale processes in different sub-regions. Correlation analyses also show the vertical extent of vertical velocity and the role of monsoon in generating submesoscale activities in the upper ocean of sub-regions. All these results suggest that the sub-regions have different regimes for submesoscale processes, e.g., Kuroshio intrusion (R1), monsoon modulation (R2), frontal effects (R3), topography wakes (R4).
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
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
Bachman S D, Taylor J R, Adams K A, et al. 2017. Mesoscale and submesoscale effects on mixed layer depth in the Southern Ocean. Journal of Physical Oceanography, 47(9): 2173–2188, doi: https://doi.org/10.1175/JPO-D-17-0034.1
Barkan R, McWilliams J C, Shchepetkin A F, et al. 2017. Submesoscale dynamics in the northern Gulf of Mexico. Part I: Regional and seasonal characterization and the role of river outflow. Journal of Physical Oceanography, 47(9): 2325–2346, doi: https://doi.org/10.1175/JPO-D-17-0035.1
Boccaletti G, Ferrari R, Fox-Kemper B. 2007. Mixed layer instabilities and restratification. Journal of Physical Oceanography, 37(9): 2228–2250, doi: https://doi.org/10.1175/jpo.3101.1
Brannigan L. 2016. Intense submesoscale upwelling in anticyclonic eddies. Geophysical Research Letters, 43(7): 3360–3369, doi: https://doi.org/10.1002/2016GL067926
Brannigan L, Marshall D P, Naveira-Garabato A, et al. 2015. The seasonal cycle of submesoscale flows. Ocean Modelling, 92: 69–84, doi: https://doi.org/10.1016/j.ocemod.2015.05.002
Callies J, Ferrari R, Klymak J M, et al. 2015. Seasonality in submesoscale turbulence. Nature Communications, 6(1): 6862, doi: https://doi.org/10.1038/ncomms7862
Cao Haijin, Fox-Kemper B, Jing Zhiyou. 2021. Submesoscale eddies in the upper ocean of the Kuroshio Extension from high-resolution simulation: Energy budget. Journal of Physical Oceanography, 51(7): 2181–2201, doi: https://doi.org/10.1175/JPO-D-20-0267.1
Cao Haijin, Jing Zhiyou. 2022. Submesoscale ageostrophic motions within and below the mixed layer of the northwestern Pacific Ocean. Journal of Geophysical Research: Oceans, 127(2): e2021JC017812, https://doi.org/10.1029/2021JC017812
Cao Haijin, Jing Zhiyou, Fox-Kemper B, et al. 2019. Scale transition from geostrophic motions to internal waves in the northern South China Sea. Journal of Geophysical Research: Oceans, 124(12): 9364–9383, doi: https://doi.org/10.1029/2019JC015575
Capet X, McWilliams J C, Molemaker M J, et al. 2008. Mesoscale to submesoscale transition in the California Current System. Part III: Energy balance and flux. Journal of Physical Oceanography, 38(10): 2256–2269, doi: https://doi.org/10.1175/2008JPO3810.1
Carton J A, Giese B S. 2008. A reanalysis of ocean climate using Simple Ocean Data Assimilation (SODA). Monthly Weather Review, 136(8): 2999–3017, doi: https://doi.org/10.1175/2007MWR1978.1
Chen Gengxin, Hou Yijun, Chu Xiaoqing. 2011. Mesoscale eddies in the South China Sea: Mean properties, spatiotemporal variability, and impact on thermohaline structure. Journal of Geophysical Research: Oceans, 116(C6): C06018, doi: https://doi.org/10.1029/2010JC006716
Chu Xiaoqing, Chen Gengxin, Qi Yiquan. 2020. Periodic mesoscale eddies in the South China Sea. Journal of Geophysical Research: Oceans, 125(1): e2019JC015139, doi: https://doi.org/10.1029/2019JC015139
D’Asaro E, Lee C, Rainville L, et al. 2011. Enhanced turbulence and energy dissipation at ocean fronts. Science, 332(6027): 318–322, doi: https://doi.org/10.1126/science.1201515
Dong Jihai, Fox-Kemper B, Zhang Hong, et al. 2020. The seasonality of submesoscale energy production, content, and cascade. Geophysical Research Letters, 47(6): e2020GL087388, doi: https://doi.org/10.1029/2020GL087388
Dong Jihai, Zhong Yisen. 2020. Submesoscale fronts observed by satellites over the northern South China Sea shelf. Dynamics of Atmospheres and Oceans, 91: 101161, doi: https://doi.org/10.1016/j.dynatmoce.2020.101161
Fox-Kemper B, Ferrari R, Hallberg R. 2008. Parameterization of mixed layer eddies. Part I: Theory and diagnosis. Journal of Physical Oceanography, 38(6): 1145–1165, doi: https://doi.org/10.1175/2007jpo3792.1
Gula J, Molemaker M J, Mcwilliams J C. 2014. Submesoscale cold filaments in the Gulf Stream. Journal of Physical Oceanography, 44(10): 2617–2643, doi: https://doi.org/10.1175/JPO-D-14-0029.1
Haine T W N, Marshall J. 1998. Gravitational, symmetric, and baroclinic instability of the ocean mixed layer. Journal of Physical Oceanography, 28(4): 634–658, doi: https://doi.org/10.1175/1520-0485(1998)028<0634:GSABIO>2.0.CO;2
Hu Jianyu, Ho C R, Xie Lingling, et al. 2020. Regional Oceanography of the South China Sea. Singapore: World Scientific, doi: https://doi.org/10.1142/11461
Hu Jianyu, Kawamura H, Hong Huasheng, et al. 2000. A review on the currents in the South China Sea: seasonal circulation, South China Sea warm current and Kuroshio intrusion. Journal of Oceanography, 56(6): 607–624, doi: https://doi.org/10.1023/A:1011117531252
Hu Jianyu, Zheng Quanan, Sun Zhenyu, et al. 2012. Penetration of nonlinear Rossby eddies into South China Sea evidenced by cruise data. Journal of Geophysical Research: Oceans, 117(C3): C03010, doi: https://doi.org/10.1029/2011JC007525
Huang Xiaorong, Jing Zhiyou, Zheng Ruixi, et al. 2020. Dynamical analysis of submesoscale fronts associated with wind-forced offshore jet in the western South China Sea. Acta Oceanologica Sinica, 39(11): 1–12, doi: https://doi.org/10.1007/s13131-020-1671-4
Jing Zhiyou, Fox-Kemper B, Cao Haijin, et al. 2021. Submesoscale fronts and their dynamical processes associated with symmetric instability in the northwest Pacific subtropical Ocean. Journal of Physical Oceanography, 51(1): 83–100, doi: https://doi.org/10.1175/JPO-D-20-0076.1
Large W G, McWilliams J C, Doney S C. 1994. Oceanic vertical mixing: A review and a model with a nonlocal boundary layer parameterization. Reviews of Geophysics, 32(4): 363–403, doi: https://doi.org/10.1029/94RG01872
Li Jianing, Dong Jihai, Yang Qingxuan, et al. 2019. Spatial-temporal variability of submesoscale currents in the South China Sea. Journal of Oceanology and Limnology, 37(2): 474–485, doi: https://doi.org/10.1007/s00343-019-8077-1
Li Jiaxun, Wang Guihua, Zhai Xiaoming. 2017. Observed cold filaments associated with mesoscale eddies in the South China Sea. Journal of Geophysical Research: Oceans, 122(1): 762–770, doi: https://doi.org/10.1002/2016JC012353
Luo Shihao, Jing Zhiyou, Qi Yiquan. 2020. Submesoscale flows associated with convergent strain in an anticyclonic eddy of the Kuroshio extension: A high-resolution numerical study. Ocean Science Journal, 55(2): 249–264, doi: https://doi.org/10.1007/s12601-020-0022-x
Lévy M, Franks P J S, Smith K S. 2018. The role of submesoscale currents in structuring marine ecosystems. Nature Communications, 9(1): 4758, doi: https://doi.org/10.1038/s41467-018-07059-3
Lévy M, Iovino D, Resplandy L, et al. 2012. Large-scale impacts of submesoscale dynamics on phytoplankton: Local and remote effects. Ocean Modelling, 43–44: 77–93, doi: https://doi.org/10.1016/j.ocemod.2011.12.003
Mahadevan A, Tandon A. 2006. An analysis of mechanisms for submesoscale vertical motion at ocean fronts. Ocean Modelling, 14(3–4): 241–256, doi: https://doi.org/10.1016/j.ocemod.2006.05.006
Mahadevan A, Tandon A, Ferrari R. 2010. Rapid changes in mixed layer stratification driven by submesoscale instabilities and winds. Journal of Geophysical Research: Oceans, 115(C3): C03017, doi: https://doi.org/10.1029/2008JC005203
McWilliams J C. 2017. Submesoscale surface fronts and filaments: Secondary circulation, buoyancy flux, and frontogenesis. Journal of Fluid Mechanics, 823: 391–432, doi: https://doi.org/10.1017/jfm.2017.294
Nan Feng, He Zhigang, Zhou Hui, et al. 2011a. Three long-lived anti-cyclonic eddies in the northern South China Sea. Journal of Geophysical Research: Oceans, 116(C5): C05002, doi: https://doi.org/10.1029/2010JC006790
Nan Feng, Xue Huijie, Xiu Peng, et al. 2011b. Oceanic eddy formation and propagation southwest of Taiwan. Journal of Geophysical Research: Oceans, 116(C12): C12045, doi: https://doi.org/10.1029/2011JC007386
Qu Tangdong, Lukas R. 2003. The bifurcation of the north equatorial current in the Pacific. Journal of Physical Oceanography, 33(1): 5–18, doi: https://doi.org/10.1175/1520-0485(2003)033<0005:tbotne>2.0.co;2
Qu Tangdong, Mitsudera H, Yamagata T. 2000. Intrusion of the North Pacific waters into the South China Sea. Journal of Geophysical Research: Oceans, 105(C3): 6415–6424, doi: https://doi.org/10.1029/1999JC900323
Rocha C B, Gille S T, Chereskin T K, et al. 2016. Seasonality of submesoscale dynamics in the Kuroshio Extension. Geophysical Research Letters, 43(21): 11304–11311, doi: https://doi.org/10.1002/2016GL071349
Rosso I, Hogg A M, Strutton P G, et al. 2014. Vertical transport in the ocean due to sub-mesoscale structures: Impacts in the Kerguelen region. Ocean Modelling, 80: 10–23, doi: https://doi.org/10.1016/j.ocemod.2014.05.001
Sasaki H, Klein P, Qiu Bo, et al. 2014. Impact of oceanic-scale interactions on the seasonal modulation of ocean dynamics by the atmosphere. Nature Communications, 5(1): 5636, doi: https://doi.org/10.1038/ncomms6636
Shcherbina A Y, D’Asaro E A, Lee C M, et al. 2013. Statistics of vertical vorticity, divergence, and strain in a developed submesoscale turbulence field. Geophysical Research Letters, 40(17): 4706–4711, doi: https://doi.org/10.1002/grl.50919
Siegelman L, Klein P, Rivière P, et al. 2020. Enhanced upward heat transport at deep submesoscale ocean fronts. Nature Geoscience, 13(1): 50–55, doi: https://doi.org/10.1038/s41561-019-0489-1
Su Zhan, Torres H, Klein P, et al. 2020. High-frequency submesoscale motions enhance the upward vertical heat transport in the global ocean. Journal of Geophysical Research: Oceans, 125(9): e2020JC016544, doi: https://doi.org/10.1029/2020JC016544
Thomas L N, Taylor J R, Ferrari R, et al. 2013. Symmetric instability in the Gulf Stream. Deep-Sea Research Part II: Topical Studies in Oceanography, 91: 96–110, doi: https://doi.org/10.1016/j.dsr2.2013.02.025
Thompson A F, Lazar A, Buckingham C, et al. 2016. Open-ocean submesoscale motions: A full seasonal cycle of mixed layer instabilities from gliders. Journal of Physical Oceanography, 46(4): 1285–1307, doi: https://doi.org/10.1175/JPO-D-15-0170.1
Tian Jiwei, Yang Qingxuan, Liang Xinfeng, et al. 2006. Observation of Luzon Strait transport. Geophysical Research Letters, 33(19): L19607, doi: https://doi.org/10.1029/2006GL026272
Wang Bin, Huang Fei, Wu Zhiwei, et al. 2009. Multi-scale climate variability of the South China Sea monsoon: A review. Dynamics of Atmospheres and Oceans, 47(1–3): 15–37, doi: https://doi.org/10.1016/j.dynatmoce.2008.09.004
Wang Shengpeng, Jing Zhao, Liu Hailong, et al. 2018. Spatial and seasonal variations of submesoscale eddies in the eastern tropical Pacific Ocean. Journal of Physical Oceanography, 48(1): 101–116, doi: https://doi.org/10.1175/JPO-D-17-0070.1
Wang Dongxiao, Liu Qinyu, Huang Rui Xin, et al. 2006. Interannual variability of the South China Sea throughflow inferred from wind data and an ocean data assimilation product. Geophysical Research Letters, 33(14): L14605, doi: https://doi.org/10.1029/2006GL026316
Wang Guihua, Su Jilan, Chu P C. 2003. Mesoscale eddies in the South China Sea observed with altimeter data. Geophysical Research Letters, 30(21): 2121, doi: https://doi.org/10.1029/2003GL018532
Woodruff S D, Worley S J, Lubker S J, et al. 2011. ICOADS Release 2.5: extensions and enhancements to the surface marine meteorological archive. International Journal of Climatology, 31(7): 951–967, doi: https://doi.org/10.1002/joc.2103
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
Xie Lingling, Zheng Quanan. 2017. New insight into the South China Sea: Rossby normal modes. Acta Oceanologica Sinica, 36(7): 1–3, doi: https://doi.org/10.1007/s13131-017-1077-0
Xue Huijie, Chai Fei, Pettigrew N, et al. 2004. Kuroshio intrusion and the circulation in the South China Sea. Journal of Geophysical Research: Oceans, 109(C2): C02017, doi: https://doi.org/10.1029/2002JC001724
Yang Xiaoxiao, Cao Haijin, Jing Zhiyou. 2021. Spatial and seasonal differences of the upper-ocean submesoscale processes in the South China Sea. Journal of Tropical Oceanography, 40(5): 10–24, doi: https://doi.org/10.11978/2020116
Yang Qingxuan, Zhao Wei, Liang Xinfeng, et al. 2017. Elevated mixing in the periphery of mesoscale eddies in the South China Sea. Journal of Physical Oceanography, 47(4): 895–907, doi: https://doi.org/10.1175/JPO-D-16-0256.1
Yu Xiaolong, Garabato A C N, Martin A P, et al. 2019. An annual cycle of submesoscale vertical flow and restratification in the upper ocean. Journal of Physical Oceanography, 49(6): 1439–1461, doi: https://doi.org/10.1175/JPO-D-18-0253.1
Yu Jie, Zheng Quanan, Jing Zhiyou, et al. 2018. Satellite observations of sub-mesoscale vortex trains in the western boundary of the South China Sea. Journal of Marine Systems, 183: 56–62, doi: https://doi.org/10.1016/j.jmarsys.2018.03.010
Zhang Zhiwei, Zhang Yuchen, Qiu Bo, et al. 2020. Spatiotemporal characteristics and generation mechanisms of submesoscale currents in the northeastern South China Sea revealed by numerical simulations. Journal of Geophysical Research: Oceans, 125(2): e2019JC015404, doi: https://doi.org/10.1029/2019JC015404
Zhang Zhiwei, Zhang Xincheng, Qiu Bo, et al. 2021a. Submesoscale currents in the subtropical upper ocean observed by long-term high-resolution mooring arrays. Journal of Physical Oceanography, 51(1): 187–206, doi: https://doi.org/10.1175/JPO-D-20-0100.1
Zhang Jinchao, Zhang Zhiwei, Qiu Bo, et al. 2021b. Seasonal modulation of submesoscale kinetic energy in the upper ocean of the northeastern South China Sea. Journal of Geophysical Research: Oceans, 126(11): e2021JC017695, doi: https://doi.org/10.1029/2021JC017695
Zheng Quanan, Xie Lingling, Xiong Xuejun, et al. 2020. Progress in research of submesoscale processes in the South China Sea. Acta Oceanologica Sinica, 39(1): 1–13, doi: https://doi.org/10.1007/s13131-019-1521-4
Zhong Yisen, Bracco A. 2013. Submesoscale impacts on horizontal and vertical transport in the Gulf of Mexico. Journal of Geophysical Research: Oceans, 118(10): 5651–5668, doi: https://doi.org/10.1002/jgrc.20402
Zhu Yaohua, Sun Juanchuan, Wang Yonggang, et al. 2019. Overview of the multi-layer circulation in the South China Sea. Progress in Oceanography, 175: 171–182, doi: https://doi.org/10.1016/j.pocean.2019.04.001
Acknowledgements
We thank NASA (http://oceancolor.gsfc.nasa.gov) for the MODIS Aqua data and the QuikSCAT forcing (http://podaac.jpl.nasa.gov), NOAA ICOADS (http://icoads.noaa.gov), and SODA (https://www2.atmos.umd.edu/;ocean/) were also part of the forcing data.
Funding
The National Key Research and Development Program of China under contract No. 2017YFA0604104; the National Natural Science Foundation of China under contract Nos 42176004, 92058201 and 41776040; the Fundamental Research Funds for the Central Universities under contract No. B220202050.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Cao, H., Meng, X., Jing, Z. et al. High-resolution simulation of upper-ocean submesoscale variability in the South China Sea: Spatial and seasonal dynamical regimes. Acta Oceanol. Sin. 41, 26–41 (2022). https://doi.org/10.1007/s13131-022-2014-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s13131-022-2014-4