Water exchange through the Kerama Gap estimated with a 25-year Pacific HYbrid Coordinate Ocean Model -- Journal of Oceanology and Limnology,2017,35(6):1287-1302

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	ZHOU Wenzheng, YU Fei, NAN Feng. Water exchange through the Kerama Gap estimated with a 25-year Pacific HYbrid Coordinate Ocean Model[J]. Journal of Oceanology and Limnology, 2017, 35(6): 1287-1302

Water exchange through the Kerama Gap estimated with a 25-year Pacific HYbrid Coordinate Ocean Model

ZHOU Wenzheng^1,2, YU Fei¹, NAN Feng¹

1 Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;
2 University of Chinese Academy of Sciences, Beijing 100049, China

Abstract:

Variations in water exchange through the Kerama Gap (between Okinawa Island and Miyakojima Island) from 1979 to 2003 were estimated with the 0.08·Pacific HYbrid Coordinate Ocean Model (HYCOM). The model results show that the mean transport through the Kerama Gap (KGT) from the Pacific Ocean to the East China Sea (ECS) was 2.1 Sv, which agrees well with the observed mean KGT (2.0 Sv) for 2009-2010. Over the time period examined, the monthly KGT varied from -10.9 Sv to 15.8 Sv and had a standard deviation of ±5.0 Sv. The water mainly enters the ECS via the subsurface layer (300-500 m) along the northeastern slope of the Kerama Gap and mainly flows out of the ECS into the southwest of the Kerama Gap. The seasonal and interannual variations of the KGT and the Kuroshio upstream transport were negatively correlated. The Kuroshio upstream transport was largest in summer and smallest in autumn while the KGT was smallest in summer (1.02 Sv) and largest in spring (2.94 Sv) and autumn (2.44 Sv). The seasonal and interannual variations in the Kuroshio downstream (across the PN-line) transport differed significantly from the Kuroshio upstream transport but corresponded well with the KGT and the sum of the transport through the Kerama Gap and the Kuroshio upstream, which indicates that information about variation in the KGT is important for determining variation in the Kuroshio transport along the PN-line.

Key words: Kerama Gap|Kuroshio|Ryukyu Current|HYbrid Coordinate Ocean Model (HYCOM)|water exchange

Received: 2016-05-08 Revised: 2016-09-26

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Articles by ZHOU Wenzheng

Articles by YU Fei

Articles by NAN Feng

References:
Andres M, Park J H, Wimbush M, Zhu X H, Chang K I, Ichikawa H. 2008a. Study of the Kuroshio/Ryukyu current system based on satellite-altimeter and in situ measurements. Journal of Oceanography, 64(6):937-950.
Andres M, Wimbush M, Park J H, Chang K I, Lim B H, Watts D R, Ichikawa H, Teague W J. 2008b. Observations of Kuroshio flow variations in the East China Sea. Journal of Geophysical Research:Oceans, 113(C5):15.
Boyer T P, Antonov J I, Baranova O K, Garcia H E, Grodsky A, Johnson D R, Locarnini R A, Mishonov A V, O'Brien T D, Seidov D, Smolyar I V, Zweng M M. 2013. World Ocean Database 2013. Data Science Journal, 90(49):153-173.
Centurioni L R, Niiler P P, Lee D K. 2004. Observations of inflow of Philippine Sea surface water into the South China Sea through the Luzon Strait. Journal of Physical Oceanography, 34(1):113-121.
Chen C T A. 2005. Tracing tropical and intermediate waters from the South China Sea to the Okinawa trough and beyond. Journal of Geophysical Research:Oceans, 110(C5):C05012.
Cummings J A, Smedstad O M. 2013. Variational data assimilation for the global ocean. In:Park S K, Xu L eds.Data Assimilation for Atmospheric, Oceanic and Hydrologic Applications (Vol. Ⅱ). Springer, Berlin Heidelberg. p.303-343.
Guo X Y, Miyazawa Y, Yamagata T. 2006. The Kuroshio onshore intrusion along the shelf break of the East China Sea:the origin of the Tsushima warm current. Journal of Physical Oceanography, 36(12):2 205-2 231.
Jin B G, Wang G H, Liu Y G, Zhang R. 2010. Interaction between the East China Sea Kuroshio and the Ryukyu current as revealed by the self-organizing map. Journal of Geophysical Research:Oceans, 115(C12):168-172.
Kelly K A, Thompson L, Cheng W, Metzger E J. 2007.Evaluation of HYCOM in the Kuroshio Extension region using new metrics. Journal of Geophysical Research:Oceans, 112(C1):18.
Lin X P, Wu D X, Lan J. 2004. The intrusion and influences of intraseasonal long Rossby waves in the East China Sea.Journal of Hydrodynamics, 16(5):621-632.
Morinaga K, Nakagawa N, Osamu K, Guo B. 1998. Flow pattern of the Kuroshio west of the main Okinawa Island.In:Proceedings of Japan-China Joint Symposium on Cooperative Study of Subtropical Circulation System.Seikai National Fisheries Research Institute, Nagasaki, Japan. p.203-210.
Na H, Wimbush M, Park J H, Nakamura H, Nishina A. 2014.Observations of flow variability through the Kerama Gap between the East China Sea and the Northwestern Pacific.Journal of Geophysical Research:Oceans, 119(2):689-703.
Nagano A, Ichikawa H, Miura T, Ichikawa K, Konda M, Yoshikawa Y, Obama K, Murakami K. 2007. Current system east of the Ryukyu Islands. Journal of Geophysical Research:Oceans, 112(C6):137-154.
Nakamura H, Nishina A, Ichikawa H, Nonaka M, Sasaki H. 2008. Deep countercurrent beneath the Kuroshio in the Okinawa Trough. Journal of Geophysical Research:Oceans, 113(C6):1 394-1 404.
Nakamura H, Nishina A, Liu Z J, Tanaka F, Wimbush M, Park J H. 2013. Intermediate and deep water formation in the Okinawa Trough. Journal of Geophysical Research:Oceans, 118(12):6 881-6 893.
Oka E, Kawabe M. 1998. Characteristics of variations of water properties and density structure around the Kuroshio in the East China Sea. Journal of Oceanography, 54(6):605-617.
Qu T D, Song Y T. 2009. Mindoro Strait and Sibutu Passage transports estimated from satellite data. Geophysical Research Letters, 36(9):269-277.
Sibuet J C, Hsu S K, Shyu C T, Liu C S. 1995. Structural and kinematic evolutions of the Okinawa Trough backarc basin. In:Taylor B ed. Backarc Basins. Springer, New York. p.343-379.
Soeyanto E, Guo X Y, Ono J, Miyazawa Y. 2014. Interannual variations of Kuroshio transport in the East China Sea and its relation to the Pacific Decadal Oscillation and mesoscale eddies. Journal of Geophysical Research:Oceans, 119(6):3 595-3 616.
Song Y T. 2006. Estimation of interbasin transport using ocean bottom pressure:theory and model for Asian marginal seas. Journal of Geophysical Research:Oceans, 111(C11):36-45.
Thoppil P G, Metzger E J, Hurlburt H E, Smedstad O M, Ichikawa H. 2016. The current system east of the Ryukyu Islands as revealed by a global ocean reanalysis. Progress in Oceanography, 141:239-258.
You S H, Yoon J H. 2004. Modeling of the Ryukyu current along the Pacific side of the Ryukyu islands. Pacific Oceanography, 2:44-51.
Yu Z T, Metzger E J, Thoppil P, Hurlburt H E, Zamudio L, Smedstad O M, Na H, Nakamura H, Park J H. 2015. Seasonal cycle of volume transport through Kerama Gap revealed by a 20-year global HYbrid Coordinate Ocean Model reanalysis. Ocean Modelling, 96:203-213.
Yuan Y. 1995. The western boundary current east of the Ryukyu Islands. Oceanographic Literature Review, 42(11):929-930.
Zheng X T, Liu Q Y, Hu H B, Miyazawa Y, Jia Y L. 2008. The study of the temporal and spatial characteristics of western boundary current East of Ruykyu submarne ridge and the transport of Kuroshio in East China Sea. Acta Oceanologica Sinica, 30(1):1-9. (in Chinese with English abstract)
Zhu X H, Han I S, Park J H, Ichikawa H, Murakami K, Kaneko A, Ostrovskii A. 2003. The northeastward current southeast of Okinawa Island observed during November 2000 to August 2001. Geophysical Research Letters, 30(2):61-79.