Extracting and analyzing current transport structures in the Kuroshio area based on Lagrangian coherent structures
-
摘要: 海流的拉格朗日运动对于研究物质输送有着重要意义，拉格朗日拟序结构(LCSs)作为研究海流结构的新型方法，相比于传统欧拉方法更为客观。本文提出了一种新的计算LCSs束的方法，基于25年的平均速度场，利用变分方法计算得到黑潮区域的气候态LCSs，并通过简化合并的方法得到了气候态LCSs束，该LCSs束能够突出地显示出海流特性和运输模式，其代表的平均拉格朗日环流有很强的约束作用，且具有鲁棒性。最终我们获得了气候态下12个月份的流场结构图，揭示了月周期性拉格朗日环流规律。本文还利用虚拟粒子输运、多年浮标轨迹以及气候态温盐异常3种方法进行了验证，与拉格朗日运输模式相吻合，证明了海流拉格朗日拟序结构的准确性和可靠性。Abstract: Lagrangian motion of fluid has important significance for studying material transport. Compared with the traditional Euler method, Lagrangian coherent structures (LCSs) as a new method to research current structures is more objective. This paper presents a new method to calculate LCSs bundles. Based on the average velocity fields of 25 years, climatological LCSs of the Kuroshio area are calculated by variational method. Then simplify and merge the LCSs to obtain climatological LCSs bundles. The LCSs bundles can show the typical current characteristics and transport patterns, represent the average Lagrangian circulation which has a strong constraint. Finally, the climatological flow structures for 12 months are obtained, revealing the periodic Lagrangian circulation rules in different months. Also, virtual particle transport, trajectories of drifters, temperature and salt anomalies distributions are used to verify the results, which are consistent with the transport patterns mentioned in this paper, proving the accuracy and reliability of the current Lagrangian coherent structures.
-
Key words:
- Kuroshio /
- Lagrangian coherent structures /
- metarial transport /
- climate state
-
图 3 气候态下的吸引型LCSs和FTLE场
a−l分别代表1−12月
Fig. 3 Monthly climatological attracting LCSs and FTLE fields
a to l represents January to December respectively
图 4 保留100%（a），40%（b）和20%（c）的吸引型LCSs
Fig. 4 Reserved attracting LCSs for 100% (a), 40% (b) and 20% (c)
图 5 LCSs简化合并流程图（a）和相似度表示例（b，c）
假设相似度表b中S24最小，将L2和L4合并为L6，得到相似度表c
Fig. 5 Flow chart of simplifing and merging LCSs (a) and an example of similarity table (b, c)
Assume that S24 in table b is the minimum, merge L2 and L4 into L6, and the similarity table c is obtained
图 6 合并前的LCSs (a)和合并后的LCSs束(b)示意图
Fig. 6 LCSs before merging (a) and LCSs bundles after merging (b)
图 7 12个月的气候态流场结构
a−l分别代表1−12月
Fig. 7 Monthly climatological flow field structures
a to l represents January to December respectively
图 9 示踪粒子初始位置（a）和运动10 d（b）、20 d（c）、30 d（d）后的LCSs输运图
Fig. 9 Initial position (a) and advected images for 10 days (b), 20 days (c) and 30 days (d) of particles
-
[1] 张灿影, 冯志纲, 张晓琨, 等. 黑潮研究进展分析[J]. 世界科技研究与发展, 2017, 39(3): 239−249.Zhang Canying, Feng Zhigang, Zhang Xiaokun, et al. Analysis on research progress of Kuroshio[J]. World Sci-Tech R&D, 2017, 39(3): 239−249. [2] Qiu Bo. The Kuroshio extension system: its large-scale variability and role in the midlatitude ocean-atmosphere interaction[J]. Journal of Oceanography, 2002, 58(1): 57−75. doi: 10.1023/A:1015824717293 [3] Jayne S R, Hogg N G, Waterman S N, et al. The Kuroshio extension and its recirculation gyres[J]. Deep-Sea Research Part I: Oceanographic Research Papers, 2009, 56(12): 2088−2099. doi: 10.1016/j.dsr.2009.08.006 [4] Qiu Bo, Chen Shuiming. Variability of the Kuroshio extension jet, recirculation gyre, and mesoscale eddies on decadal time scales[J]. Journal of Physical Oceanography, 2005, 35(11): 2090−2103. doi: 10.1175/JPO2807.1 [5] 刘晓辉, 陈大可, 董昌明, 等. 利用拉格朗日方法研究台湾东北黑潮路径变化[J]. 中国科学: 地球科学, 2016, 59(2): 268−280. doi: 10.1007/s11430-015-5176-5Liu Xiaohui, Chen Dake, Dong Changming, et al. Variation of the Kuroshio intrusion pathways northeast of Taiwan using the Lagrangian method[J]. Science China: Earth Sciences, 2016, 59(2): 268−280. doi: 10.1007/s11430-015-5176-5 [6] Yamashiro T, Kawabe M. Monitoring of position of the Kuroshio axis in the Tokara Strait using sea level data[J]. Journal of Oceanography, 1996, 52(6): 675−687. doi: 10.1007/BF02239459 [7] Yamashiro T, Kawabe M. Variations of the Kuroshio axis south of Kyushu in relation to the large meander of the Kuroshio[J]. Journal of Oceanography, 2002, 58(3): 487−503. doi: 10.1023/A:1021265315858 [8] Ambe D, Imawaki S, Uchida H, et al. Estimating the Kuroshio axis south of Japan using combination of satellite altimetry and drifting buoys[J]. Journal of Oceanography, 2004, 60(2): 375−382. doi: 10.1023/B:JOCE.0000038343.31468.fe [9] Tseng Y H, Shen Maolin, Jan S, et al. Validation of the Kuroshio current system in the dual-domain Pacific Ocean model framework[J]. Progress in Oceanography, 2012, 105: 102−124. doi: 10.1016/j.pocean.2012.04.003 [10] Nan Feng, Xue Huijie, Yu Fei. Kuroshio intrusion into the South China Sea: a review[J]. Progress in Oceanography, 2015, 137: 314−333. doi: 10.1016/j.pocean.2014.05.012 [11] Haller G, Yuan G. Lagrangian coherent structures and mixing in two-dimensional turbulence[J]. Physica D: Nonlinear Phenomena, 2000, 147(3/4): 352−370. [12] Peacock T, Dabiri J. Introduction to focus issue: Lagrangian coherent structures[J]. Chaos, 2010, 20(1): 017501. doi: 10.1063/1.3278173 [13] Peacock T, Haller G. Lagrangian coherent structures: the hidden skeleton of fluid flows[J]. Physics Today, 2013, 66(2): 41−47. doi: 10.1063/PT.3.1886 [14] Haller G. Lagrangian coherent structures[J]. Annual Review of Fluid Mechanics, 2015, 47: 137−162. doi: 10.1146/annurev-fluid-010313-141322 [15] Samelson R M. Lagrangian motion, coherent structures, and lines of persistent material strain[J]. Annual Review of Marine Science, 2013, 5: 137−163. doi: 10.1146/annurev-marine-120710-100819 [16] Hadjighasem A, Farazmand M, Blazevski D, et al. A critical comparison of Lagrangian methods for coherent structure detection[J]. Chaos, 2017, 27(5): 053104. doi: 10.1063/1.4982720 [17] Shadden S C, Lekien F, Marsden J E. Definition and properties of Lagrangian coherent structures from finite-time Lyapunov exponents in two-dimensional aperiodic flows[J]. Physica D: Nonlinear Phenomena, 2005, 212(3/4): 271−304. [18] d’Ovidio F, Fernández V, Hernández-García E, et al. Mixing structures in the Mediterranean Sea from finite-size Lyapunov exponents[J]. Geophysical Research Letters, 2004, 31(17): L17203. [19] 黄高龙, 韦惺, 詹海刚. 吕宋海峡浮标轨迹的拉格朗日拟序结构分析[J]. 热带海洋学报, 2015, 34(1): 15−22. doi: 10.3969/j.issn.1009-5470.2015.01.003Huang Gaolong, Wei Xing, Zhan Haigang. Lagrangian analysis of drifter trajectories near the Luzon Strait[J]. Journal of Tropical Oceanography, 2015, 34(1): 15−22. doi: 10.3969/j.issn.1009-5470.2015.01.003 [20] Haller G. A variational theory of hyperbolic Lagrangian Coherent Structures[J]. Physica D: Nonlinear Phenomena, 2011, 240(7): 574−598. doi: 10.1016/j.physd.2010.11.010 [21] Farazmand M, Haller G. Computing Lagrangian coherent structures from their variational theory[J]. Chaos, 2012, 22(1): 013128. doi: 10.1063/1.3690153 [22] Farazmand M, Haller G. Attracting and repelling Lagrangian coherent structures from a single computation[J]. Chaos, 2013, 23(2): 023101. doi: 10.1063/1.4800210 [23] Farazmand M, Blazevski D, Haller G. Shearless transport barriers in unsteady two-dimensional flows and maps[J]. Physica D: Nonlinear Phenomena, 2014, 278-279: 44−57. doi: 10.1016/j.physd.2014.03.008 [24] Haller G, Beron-Vera F J. Coherent Lagrangian vortices: the black holes of turbulence[J]. Journal of Fluid Mechanics, 2013, 731: R4. doi: 10.1017/jfm.2013.391 [25] Wang Y, Olascoaga M J, Beron-Vera F J. Coherent water transport across the South Atlantic[J]. Geophysical Research Letters, 2015, 42(10): 4072−4079. doi: 10.1002/2015GL064089 [26] Beron-Vera F J, Olascoaga M J, Brown M G, et al. Invariant-tori-like Lagrangian coherent structures in geophysical flows[J]. Chaos, 2010, 20(1): 017514. doi: 10.1063/1.3271342 [27] Yuan G C, Pratt L J, Jones C K R T. Cross-jet lagrangian transport and mixing in a 2½-layer model[J]. Journal of Physical Oceanography, 2004, 34(9): 1991−2005. doi: 10.1175/1520-0485(2004)034<1991:CLTAMI>2.0.CO;2 [28] Beron-Vera F J, Olascoaga M J, Brown M G, et al. Zonal jets as meridional transport barriers in the subtropical and polar lower stratosphere[J]. Journal of the Atmospheric Sciences, 2012, 69(2): 753−767. doi: 10.1175/JAS-D-11-084.1 [29] Olascoaga M J, Beron-Vera F J, Haller G, et al. Drifter motion in the Gulf of Mexico constrained by altimetric Lagrangian coherent structures[J]. Geophysical Research Letters, 2013, 40(23): 6171−6175. doi: 10.1002/2013GL058624 [30] Copernicus Marine Environment Monitoring Service. SEALEVEL_GLO_PHY_L4_REP_OBSERVATIONS_008_047[DB/OL]. [2019–01–05]. http://marine.copernicus.eu/services-portfolio/access-to-products/?option=com_csw&view=details&product_id=SEALEVEL_GLO_PHY_L4_REP_OBSERVATIONS_008_047 [31] NOAA‘s Atlantic Oceanographic and Meteorological Laboratory. Global Drifter Data[DB/OL].[2019–01–05]. http://www.aoml.noaa.gov/phod/gdp/science.php. [32] Copernicus Marine Environment Monitoring Service. MULTIOBS_GLO_PHY_REP_015_002[DB/OL]. [2019–01–05]. http://marine.copernicus.eu/services-portfolio/access-to-products/?option=com_csw&view=details&product_id=MULTIOBS_GLO_PHY_REP_015_002. [33] Onu K, Huhn F, Haller G. LCS tool: a computational platform for Lagrangian coherent structures[J]. Journal of Computational Science, 2015, 7: 26−36. doi: 10.1016/j.jocs.2014.12.002 [34] Duran R, Beron-Vera F J, Olascoaga M J. Extracting quasi-steady Lagrangian transport patterns from the ocean circulation: an application to the Gulf of Mexico[J]. Scientific Reports, 2018, 8: 5218. doi: 10.1038/s41598-018-23121-y [35] Yu Hongfeng, Wang Chaoli, Shene C K, et al. Hierarchical streamline bundles[J]. IEEE Transactions on Visualization and Computer Graphics, 2012, 18(8): 1353−1367. doi: 10.1109/TVCG.2011.155 [36] 王辉赞, 魏林进, 张全礼, 等. 台湾以东黑潮路径识别与变化规律[J]. 海洋与湖沼, 2018, 49(2): 271−279.Wang Huizan, Wei Linjin, Zhang Quanli, et al. Identification of the Kuroshio path east of Taiwan and its variation[J]. Oceanologia et Limnologia Sinica, 2018, 49(2): 271−279. [37] 于振娟. 东海黑潮流轴的变化及日本以南黑潮大弯曲同青岛降水量的关系[J]. 海洋科学, 1988(4): 6−11.Yu Zhenjuan. Relationship of variation of axial position of the Kuroshio in the East China Sea and its meanders south of Japan with the precipitation in Qingdao[J]. Marine Science, 1988(4): 6−11. -
下载:
点击查看大图
图(11)
计量
- 文章访问数: 90
- HTML全文浏览量: 35
- PDF下载量: 12
- 被引次数: 0
