The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY (한국해양학회지:바다)

The Korean Society of Oceanography (한국해양학회)
권호 표지
DOI QR코드

DOI QR Code

Physical Characteristics and Classification of the Ulleung Warm Eddy in the East Sea (Japan Sea)

동해 울릉 난수성 소용돌이의 물리적 특성 및 분류

  • SHIN, HONG-RYEOL (Department of Atmospheric Science, Kongju National University) ;
  • KIM, INGWON (Department of Atmospheric Science, Kongju National University) ;
  • KIM, DAEHYUK (Department of Atmospheric Science, Kongju National University) ;
  • KIM, CHEOL-HO (Ocean Circulation and Climate Research Center Korea Institute of Ocean Science & Technology) ;
  • KANG, BOONSOON (Ocean Research Division, Korea Hydrographic and Oceanographic Agency) ;
  • LEE, EUNIL (Ocean Research Division, Korea Hydrographic and Oceanographic Agency)
  • 신홍렬 (공주대학교 대기과학과) ;
  • 김인권 (공주대학교 대기과학과) ;
  • 김대혁 (공주대학교 대기과학과) ;
  • 김철호 (한국해양과학기술원 해양순환.기후연구센터) ;
  • 강분순 (국립해양조사원 해양과학조사연구실) ;
  • 이은일 (국립해양조사원 해양과학조사연구실)
  • Received : 2019.03.10
  • Accepted : 2019.05.29
  • Published : 2019.05.31
Download PDF
⟨ Previous Next ⟩

Abstract

The physical characteristics of the Ulleung Warm Eddy (UWE) and its relationship with the East Korea Warm Current (EKWC) were analyzed using the CMEMS (Copernicus Marine Environment Monitoring Service) satellite altimetry data and the CTD data of the National Institute of Fisheries Science (NIFS) near the Ulleung Basin from 1993 to 2017. The distribution of the UWEs coupled with EKWC accounts for 81% of the total number of the UWEs. Only 7% of the total eddies are completely separated from the EKWC. The UWE has the characteristics of high temperature and high salinity water inside of it when it is formed from the EKWC. However, when the UWE is wintering, its internal structure changes greatly. In the winter, surface homogeneous layer of $10^{\circ}C$ and 34.2 psu inside of the UWE is produced by vertical convection from sea-surface cooling, and deepened to a maximum depth of approximately 250 m in early spring. In summer, the UWE changes into a structure with a stratified structure in the upper layer within a depth of 100 m and a homogeneous layer made in winter in the lower layer. 62 UWEs were produced for 25 years from 1993 to 2017. on average, 2.5 UWEs were formed annually, and the average life span was 259 days (approximately 8.6 months). The average size of the UWEs is 98 km in the east-west direction and 109 km in the north-south direction. The average size of UWE using satellite altimetric data is estimated to be 1~25 km smaller than that using water temperature cross-sectional data.

울릉 난수성 소용돌이의 물리적 특성 및 동한난류와의 관계를 울릉분지 주변 해역에서 1993년부터 2017년까지의 CMEMS (Copernicus Marine Environment Monitoring Service) 위성 고도계 자료 및 국립수산과학원(NIFS)의 CTD 자료를 사용하여 분석하였다. 울릉 난수성 소용돌이가 동한난류와 연결되어 있는 분포는 전체 소용돌이 숫자의 81%를 차지하며, 울릉 난수성 소용돌이가 동한난류로부터 완전히 분리되어 있는 형태는 7%에 불과하다. 울릉 난수성 소용돌이는 동한난류로부터 형성될 당시에는 그 내부에 고온, 고염의 대마난류의 해수특성을 보유하지만, 월동을 하는 경우에는 내부구조가 크게 변한다. 겨울에는 해수면 냉각에 의한 수직 대류에 의해 소용돌이의 내부에 $10^{\circ}C$, 34.2 psu의 표층 균질층이 만들어지며, 초봄에 최대 약 250 m 수심까지 깊어진다. 여름에는 소용돌이는 수심 100 m 이내의 상층에 성층구조, 하층에는 겨울철에 만들어진 균질층이 남아있는 구조로 변화한다. 1993년부터 25년 동안 62개의 울릉 난수성 소용돌이가 생성되었다. 매년 평균 2.5개의 울릉 난수성 소용돌이가 발생하였고, 평균 수명은 259일(약 8.6개월) 이었다. 울릉 난수성 소용돌이의 평균 크기는 동서방향으로 약 97 km, 남북방향으로 약 109 km 이다. 위성 고도계 자료를 사용한 경우의 울릉 난수성 소용돌이의 평균 크기가 CTD 수온 단면 자료를 사용한 경우보다 1~25 km 작게 산정된다.

Keywords

GHOHBG_2019_v24n2_298_f0001.png 이미지

Fig. 1. The locations of CTD observation stations provided by NIFS (National Institute of Fisheries Science). Black rectangle indicates the region of interest for the Ulleung Warm Eddy.

GHOHBG_2019_v24n2_298_f0002.png 이미지

Fig. 2. Grid points for the correction of the CMEMS data (▲: tidal station, □ and ○: grid points to be calibrated).

GHOHBG_2019_v24n2_298_f0003.png 이미지

Fig. 3. Distributions of sea level anomaly (SLA). (A) Before and (B) after the correction.

GHOHBG_2019_v24n2_298_f0004.png 이미지

Fig. 4. The ocean current map and study area of the East Sea. Black rectangle indicates the region of interest for the Ulleung Warm Eddy (modified from Park et al., 2013).

GHOHBG_2019_v24n2_298_f0005.png 이미지

Fig. 5. Search process of the Ulleung Warm Eddy (UWE) using the sea level anomaly (black curve) data in in July 4th, 2011. (A) The black dots indicate the minimum flow velocity. (B) The red dots indicate that the V-G algorithm is satisfied. (C) The blue areas indicate the area where the Okubo-Weiss parameter (W) is less than -0.2σ. (D) Red points and the blue areas indicate the only areas where the relative vorticity is negative (warm eddies).

GHOHBG_2019_v24n2_298_f0006.png 이미지

Fig. 6. The number of generations of the UWEs at each year from 1993 to 2017.

GHOHBG_2019_v24n2_298_f0007.png 이미지

Fig. 7. The number of monthly (A) generations and (B) extinctions of the UWEs.

GHOHBG_2019_v24n2_298_f0008.png 이미지

Fig. 8. The lifespan of the UWEs.

GHOHBG_2019_v24n2_298_f0009.png 이미지

Fig. 9. Four types of the UWE pattern according to distributions of the East Korean Warm Current (EKWC). (A) Type I (enclosed pattern by the EKWC), (B) Type II (coupled pattern by the EKWC), (C) Type III (warm streamer pattern) and (D) Type IV (independent pattern). The black and white arrows represent the mainstream of the EKWC (or the Tshshima Warm Current) and the UWE, respectively. The current vector shows the velocity field computed from the SSH during 1993-2017.

GHOHBG_2019_v24n2_298_f0010.png 이미지

Fig. 10. Seasonal changes of the UWE ’s temperature (upper pannel) and salinity (lower pannel) vertical structure formed in January 2007.

GHOHBG_2019_v24n2_298_f0011.png 이미지

Fig. 11. Seasonal changes of the UWE ’s temperature (upper pannel) and salinity (lower pannel) vertical structure in 2015.

GHOHBG_2019_v24n2_298_f0012.png 이미지

Fig. 12. SSH contour (red) representing the EKWC and the UWE in February 26th, 2013. The concentric circular closed curve of the SSH contour indicates the UWE, the black arrows along the line 104 through the center of the UWE in the vicinity of 37 ° N are the geostrophic velocity vectors. The light blue region shows the area with the Okubo-Weiss parameter W <0 (eddy range).

GHOHBG_2019_v24n2_298_f0013.png 이미지

Fig. 13. Comparison of the size of the UWE calculated from SSH (A) and temperature vertical section (B and D) at line 104 in February 2013. (A and B) The blue line shows the Okubo-Weiss method (O-W), the red solid line shows the Winding Angle method (W-A), and the green solid line shows the geostrophic velocity method of Vector Geometry algorithm (velocity). (C and D) Methods to estimate the UWE size by using the isotherm of the thermocline (CTD), 10℃ isotherm at 100m depth (100m 1 0℃) and outermost isotherm at 200m depth (200m T) in water temperature vertical section are shown.

GHOHBG_2019_v24n2_298_f0014.png 이미지

Fig. 14. The average size of the UWEs calculated by maximum velocity method in (A) the east-west direction and (B) the north-south direction.

GHOHBG_2019_v24n2_298_f0015.png 이미지

Fig. 15. The average size of the UWEs calculated by O-W method in (A) the east-west direction and (B) the north-south direction.

GHOHBG_2019_v24n2_298_f0016.png 이미지

Fig. 16. Size changes in the east-west direction and the north-south direction of the UWE generated in July 2014.

GHOHBG_2019_v24n2_298_f0017.png 이미지

Fig. 17. Schematics of three UWE patterns according to distributions of the EKWC. (A) Coupled pattern, (B) warm streamer pattern, (C) independent pattern. The black arrows indicate the mainstream of the EKWC and Tshshima Warm Current, and the red arrow represents the UWE.

GHOHBG_2019_v24n2_298_f0018.png 이미지

Fig. 18. Ulleung Warm Eddy patters. (A) Coupled (W1) and Warm Streamer (W2) patterns in May 21th, 2010, and (B) Coupled (W3) and Independent (W4) patterns in July 25th, 2011.

GHOHBG_2019_v24n2_298_f0019.png 이미지

Fig. 19. Schematic illustration of seasonal change of the UWE’s temperature (T) and salinity (S) vertical structure.

Table 1. The average size of the UWEs calculated from altimetric data (SSH) and vertical section of water temperature by type

GHOHBG_2019_v24n2_298_t0001.png 이미지

References

  1. An, H., K.S. Shim and H.-R. Shin, 1994. On the warm eddies in the southwestern part of the East Sea (the Japan sea). J. Korean Society. Oceanogr., 29(2): 152-163.
  2. Arruda, W., D. Nof and J.J. O'Brien, 2004. Does the Ulleung eddy owe its existence to beta and nonlinearities? Deep Sea Res. I, 51: 2073-2090. https://doi.org/10.1016/j.dsr.2004.07.014
  3. Chaigneau, A., 2005. Eddy characteristics in the eastern South Pacitic. J. Geophys. Res., 110: C06005, doi:10.1029/2004JC002815.
  4. Chaigneau, A., A. Gizolme and C. Crados, 2008. Mesoscale eddies off Peru in altimeter records: Identificatioin algorithms and eddy spatio-temporal patterns. Prog., Oceanogr., 79(2-4): 106-119. https://doi.org/10.1016/j.pocean.2008.10.013
  5. Chaigneau, A., G. Eldin and B. Deqitte, 2009. Eddy activity in the four major upwelling systems from satellite altimetry (1992-2007). Prog. Oceanogr., 83: 117-123. https://doi.org/10.1016/j.pocean.2009.07.012
  6. Chelton, D.B., M.G. Schlax. R.M. Samelson and R.A. de Szo, 2007. Global observations of large oceanic eddies. Geophys. Res. Lett., 34: L15606, doi:10.1029/2007GL030812.
  7. Chelton, D.B., M.G. Schlax, R.M. Samelson and T.A. de Szoeke, 2011. Global observations of nonlinear mesoscale eddies. Pro. Oceanogr., 91:167-216, doi:10.1016/j.pocean.2911.01.002.
  8. Choi, B.J., D.S. Byun and K.H. Kang, 2012. Satellite-altimeter-derived East Sea surface currents: estimation, description and variability pattern. J. Korea. Soc. Oceanogr., 17: 225-242.
  9. Ichiye, T. and K. Takano, 1988. Mesoscale eddies in the Japan Sea. La Mer, 26: 69-76.
  10. Isern-Fontanet, J., E. Garcia-Ladona and J. Font, 2003. Identification of marine eddies from altimetric maps. J. Atmos. Oceanic Technol., 20: 772-778. https://doi.org/10.1175/1520-0426(2003)20<772:IOMEFA>2.0.CO;2
  11. Isern-Fontanet, J., J. Font, E. Garcia-Ladona, M. Emelianov, C. Millot and I. Taupier-Letage, 2004. Spatial structure of anticyclonic eddies in the Algerian basin (Mediterranean Sea) analyzed using the Okubo-Weiss parameter. Deep-Sea Res. II, 51: 3009-3028. https://doi.org/10.1016/j.dsr2.2004.09.013
  12. Isern-Fontanet, J., E. Garcia-Ladona and J. Font, 2006. Vortices of the Mediterranean Sea: An Altimeteric Perspective. J. Physic. Oceanogr., 36: 87-103. https://doi.org/10.1175/JPO2826.1
  13. Isoda, Y. and S.I. Saitoh, 1993. The Northward Intruding Eddy along the East Coast of Korea. J. Oceanogr., 49: 443-458. https://doi.org/10.1007/BF02234959
  14. Katoh, O., 1994. Structure of the Tsushima Current in the southwestern Japan Sea. J. Oceanogr., 50: 317-338. https://doi.org/10.1007/BF02239520
  15. Kim, J.M., 2019. Influence of Dok Cold Eddy movement ont the East Korea Warm Current fluctuation. M.S. Thesis, Kunsan National University (in Korean), Kusan, 108 pp.
  16. Lee, D.K. and P. Niiler, 2005. The energetic surface circulation patterns of the Japan/East Sea. Deep-Sea Res. II, 52 : 1547-1563. https://doi.org/10.1016/j.dsr2.2003.08.008
  17. Lee, D.K. and P. Niiler, 2010a. Surface circulation in the southwestern Japan/East Sea as observed from drifters and sea surface height. Deep-Sea Res. I, 57: 1222-1232. https://doi.org/10.1016/j.dsr.2010.06.003
  18. Lee, D.K. and P. Niiler, 2010b. Eddies in the southwestern East/Japan Sea. Deep-Sea Res. I, 57: 1233-1242. https://doi.org/10.1016/j.dsr.2010.06.002
  19. Lee, G.H., 2010. Surface circulation in the East Sea from surface drifters and altimetry. M.S. Thesis, Kunsan National University, Gunsan, 106 pp.
  20. Lee, G.J., 2013. Mesoscale eddies in the East/Japan Sea derived from low-resolution gridded altimeter data : Detection algorithms and chatacteristics of statistical eddy properties. M.S. Thesis, Seoul National University (in Korean with English abstract), Seoul, 71 pp.
  21. Lie, H.J., S.K. Byun, I. Bang and C.H. Cho, 1995. Physical Structure of eddies in the southwestern East Sea. J. Korean Society. Oceanogr., 30(3): 170-183.
  22. Matsuoka, D., F. Araki, Y. Inoue and H. Sasaki, 2016. A New Approach to Oean Eddy Detection, Tracking, and Ebent Visualization. Procedia Computer Science, 80: 1601-1611. https://doi.org/10.1016/j.procs.2016.05.491
  23. Mitchell, D.A., W.J. Taegue, M. Wimbush, D.R. Watts and G.G. Sutyrin, 2005. The Dok Cold Eddy. J. Physic. Oceanogr., 35: 273-288. https://doi.org/10.1175/JPO-2684.1
  24. Morrow, R., F. Birol, D. Griffin and J. Sudre, 2004. Divergent pathways of cyclonic and anti-cyclonic ocean eddies. Geophys. Res. Lett., 31: L24311, doi:10.1029/2004GL020974.
  25. Nencioli, F., C. Dong, T. Dickey, L. Washburn and McWilliams, 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. J. Atmos. Oceanic Technol., 27(3): 564-579. https://doi.org/10.1175/2009JTECHO725.1
  26. Park, J.J. and K. Kim, 2013. Deep currents obtained from Argo float trajectories in the Japan/East Sea. The Sea, Deep-Sea Res. II, 85: 169-181. https://doi.org/10.1016/j.dsr2.2012.07.032
  27. Park, K.-A., J.-E. Park, B.-J. Choi, D.-S. Byun and E.-I. Lee, 2013. An oceanic current map of the East Sea. The Sea, 18: 234-265. https://doi.org/10.7850/jkso.2013.18.4.234
  28. Sadarjeon, I.A. and F.H. Post, 2000. Detection, quantification, and tracking of vortices using streamline geometry. Comput. Graphics, 24: 333-341. https://doi.org/10.1016/S0097-8493(00)00029-7
  29. Saraceno, M., P.T. Strub and P.M. Kosro, 2008. Estimates of sea surface height and near-surface alongshore coastal currents from combinations of altimeters and tide gauges. J.Geophys. Res., 113: C11013, doi:10.1029/2008JC004756.
  30. Shin, H.R., C.-W. Shin, C. Kim, C.-K. Byun and S.C. Hwang, 2005. Movement and structural variation of warm eddy WE92 for three years in the Western East/Japan Sea. Deep-Sea Res. II, 52: 1742-1762. https://doi.org/10.1016/j.dsr2.2004.10.004
  31. Shin, H.-R., S.-K. Byun, C. Kim, S.C. Hwang and C.-W. Shin, 1995. The characteristics of the structure of a warm eddy observed to the northwest of Ulleungdo in 1992. J. Korean Society. Oceanogr., 30: 39-56 (in Korean with English abstract).
  32. Shin, H.-R., Y. Nagata and J. Yoshida, 1992. Detailed structure and water-type distribution of the warm-core ring 86B, September 1987. Deep-Sea Res. Part A, 39: S115-S130. https://doi.org/10.1016/S0198-0149(11)80008-7
  33. Tomosada, A., 1986. Generation and decay of Kuroshio warm corea rings. Deep-Sea Res., 33: 1475-1486. https://doi.org/10.1016/0198-0149(86)90063-4
  34. Yasuda, I., K. Okuda and J. Li, 1992. Evolution of a Kuroshio warm-core ring variability of the hydrographic structure. Deep-Sea Res., 39(S1): S131-S161. https://doi.org/10.1016/S0198-0149(11)80009-9

Cited by

  1. Influence of Sediment Resuspension on the Biological Pump of the Southwestern East Sea (Japan Sea) vol.8, 2019, https://doi.org/10.3389/feart.2020.00144