Abstract
This study introduces the East Asian Marginal Seas (EAMS) reanalysis system and evaluates its products from 1982 to 2006. The EAMS reanalysis system consists of an ocean circulation model with 0.25° horizontal grid spacing and a data assimilation module. Temperature profiles taken by ship and Argo floats as well as satellite-borne sea surface temperature (SST) were assimilated into the model by applying the ensemble Kalman filter every 7 days. The reanalyzed oceanic fields were compared with ones by the control run without data assimilation to assess the impact of the data assimilation. The assimilative model significantly improved the horizontal structures of SST, sea surface height (SSH), vertical structure of temperature, and volume transports through the major straits. Root-mean-square error (RMSE) of SST decreased from 1.0 to 0.6°C. Horizontal and vertical distribution of subsurface temperature was corrected close to the observed values. High SSH variability in the south of Japan and in the Kuroshio extension region was partially restored. Overshooting of the Kuroshio Current and the East Korea Warm Current was suppressed to the south by the data assimilation. SSH and surface circulation in the Oyashio region and in the East Sea (also known as the Sea of Japan) recovered, which corrected the sea level difference between the East Sea and the Pacific Ocean and produced realistic transport through the Korea Strait. The reanalysis well resolved transport through the Korea Strait. The correlation coefficient with the transport based on an Acoustic Doppler Current Profiler measurement was 0.70 and the RMSE was 0.37 Sv (106 m3/s), whereas those were 0.59 and 0.43 Sv in the control run, respectively. The EAMS reanalysis dataset may help us to understand circulation variations in the marginal seas and to investigate factors controlling volume and heat transport.
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References
Burgers G, van Leeuwen PJ, Evensen G (1998) Analysis scheme in the ensemble Kalman Filter. Mon Weather Rev 126:1719–1724
Carton JA, Giese BS, Grodsky SA (2005) Sea level rise and the warming of the oceans in the Simple Ocean Data Assimilation (SODA) ocean reanalysis. J Geophys Res-Oceans 110:C09006. doi: 10.1029/2004JC002817
Chang YS, Zhang SQ, Rosati A, Delworth TL, Stern WF (2013) An assessment of oceanic variability for 1960-2010 from the GFDL ensemble coupled data assimilation, Clim Dyn 40:775–803
Chapman DC (1985) Numerical treatment of cross-shelf open boundaries in a barotropic coastal ocean model. J Phys Oceanogr 15:1060–1075
Cho Y-K, Kim K (2000) Branching of the Tsushima Current in the Korea Strait. J Phys Oceanogr 30:2788–2797
Cho Y-K, Seo G-H, Choi B-J, Kim S, Kim Y, Dever EP (2009) Connectivity among straits of the Northwest Pacific Marginal Seas. J Geophys Res-Oceans 114:C06018. doi: 10.1029/2008JC005218
Chu PC, Li R (2000) South China Sea isopycnal-surface circulation. J Phys Oceanogr 30:2419–2438
Deng Z, Tang Y, Wang G (2010) Assimilation of Argo temperature and salinity profiles using a bias-aware localized EnKF system for the Pacific Ocean. Ocean Model 35:187–205
Egbert GD, Erofeeva SY (2002) Efficient inverse modeling of barotropic ocean tides. J Atmos Ocean Tech 19:183–204
Evensen G (1994) Sequential data assimilation with a nonlinear quasi-geostrophic model using Monte Carlo methods to forecast error statistics. J Geophys Res-Oceans 99:10143–10162
Evensen G (2003) The Ensemble Kalman Filter: theoretical formulation and practical implementation. Ocean Dyn 53:343–367
Fang G, Zhao B, Zhu Y (1991) Water volume transport through the Taiwan Strait and the continental shelf of the East China Sea measured with current meters. In: Takano K (ed) Oceanography of Asian Marginal Seas. Elsevier, Amsterdam, Netherlands, pp 345–358
Flather RA (1976) A tidal model of the northwest European continental shelf. Memoires de la Society Royal des Sciences de Liege 6 series 10:141–164
Fukudome K, Yoon J-H, Ostrovskii A, Takikawa T, Han I-S (2010) Seasonal volume transport variation in the Tsushima Warm Current through the Tsushima Straits from 10 years of ADCP observations. J Oceanogr 66:539–551
Gaspari G, Cohn SE (1999) Construction of correlation functions in two and three dimensions. Q J Roy Meteor Soc 125:723–757. doi: 10.1002/qj.49712555417
Haidvogel DB, Arango HG, Hedstrom K, Beckmann A, Malanotte-Rizzoli P, Shchepetkin AF (2000) Model evaluation experiments in the North Atlantic Basin: simulations in nonlinear terrainfollowing coordinates. Dyn Atmos Oceans 32:239–281
Hamil TM, Whitaker JS, Snyder C (2001) Distance-dependent filtering of background-error covariance estimates in an ensemble Kalman filter. Mon Weather Rev 129:2776–2790
Han GJ, Li W, Zhang XF, Li D, He ZJ, Wang XD, Wu XR, Yu T, Ma JR (2011) A regional ocean reanalysis system for China coastal waters and adjacent seas. Adv Atmos Sci 28:682–690
Houtekamer PL, Mitchell HL (1998) Data assimilation using an ensemble Kalman filter technique. Mon Weather Rev 126:796–811
Houtekamer PL, Mitchell HL (2001) A sequential ensemble Kalman Filter for atmospheric data assimilation. Mon Weather Rev 129:123–137
Hsin YC, Wu CR, Chao SY (2012) An updated examination of the Luzon Strait transport. J Geophys Res-Oceans 117:C03022. doi: 10.1029/2011JC007714
Isobe A (1994) On the Tsushima Warm Current in the Tsushima/Korea Straits. Kaiyo Mon 26:802–809 (in Japanese)
Liang WD, Tang TY, Yang YJ, Ko MT, Chuang WS (2003) Upper ocean currents around Taiwan. Deep-Sea Res Pt II 50:1085–1105. doi:10.1016/S0967-0645(03)00011-0
Lee T, Awaji T, Balmaseda MA, Greiner E, Stammer D (2009) Ocean state estimation for climate research. Oceanography 22:160–167
Lyu SJ, Kim K (2003) Absolute transport from the sea level difference across the Korea Strait. Geophys Res Lett 30:1285. doi: 10.1029/2002GL016233
Lyu SJ, Kim K (2005) Subinertial to interannual transport variations in the Korea Strait and their possible mechanisms. J Geophys Res-Oceans 110:C12016. doi: 10.1029/2004JC002651
Miyazawa Y, Zhang R, Guo X, Tamura H, Ambe D, Lee J-S, Okuno A, Yoshinari H, Setou T, Komatsu K (2009) Water mass variability in the western North Pacific detected in a 15-year eddy resolving ocean reanalysis. J Oceanogr 65:737–756
Mellor G, Yamada T (1974) A hierarchy of turbulence closure models for planetary boundary layers. J Atmos Sci 31:1791–1806
Menemenlis D, Hill C, Adcroft A, Campin J, Cheng B, Ciotti B, Fukumori I, Koehl A, Heimbach P, Henze C, Lee T, Stammer D, Taft J, Zhang J (2005) NASA supercomputer improves prospects for ocean climate research. Eos 86:89–96
Stammer D, Taft J, Zhang J (2005) NASA supercomputer improves prospects for ocean climate research. Eos 86:89–96
Nishimura K, Hirose N, Fukudome K (2008) Long-term estimation of volume transport through the Tsushima Straits. Rep Res Inst Appl Mech 135:113–118 (in Japanese)
Oke PR, Schiller A, Griffin DA, Brassington GB (2005) Ensemble data assimilation for an eddy-resolving ocean model of the Australian Region. Q J Roy Meteor Soc 131:3301–3311
Oke PR, Brassington GB, Griffin DA, Schiller A (2008) The Bluelink Ocean Data Assimilation System (BODAS). Ocean Model 20:46–70. doi: 10.1016/j.ocemod.2007.11.002
Ohshima KI (1994) The flow system in the Sea of Japan caused by a sea level difference through shallow straits. J Geophys Res-Oceans 99:9925–9940
Rio MH, Guinehut S, Larnicol G (2011) New CNES-CLS09 global mean dynamic topography computed from the combination of GRACE data, altimetry, and in situ measurements. J Geophys Res-Oceans 116:C07018. doi: 10.1029/2010JC006505
Schur I (1911) Bernerkungen sur Theorie Der Beschrankten Bilinearformen Mit Unendlich Vielen veranderlichen. J Math 140:1–28
Seo G-H, Kim S, Choi B-J, Cho Y-K, Kim YH (2009) Implementation of the Ensemble Kalman Filter into a Northwest Pacific Ocean Circulation Model. In: Park SK, Xu L (eds) Data Assimilation for Atmospheric, Oceanic and Hydrologic Applications. Springer, Berlin, pp 341–352
Seo G-H, Choi B-J, Cho Y-K, Kim YH, Kim S (2010) Assimilation of sea surface tempere in the northwest Pacific and its marginal seas using the ensemble Kalman filter. Ocean Sci J 45:225–242
Shchepetkin AF, McWilliams JC (2005) The Regional Ocean Modeling System: a split-explicit, free-surface, topography following coordinates ocean model. Ocean Model 9:347–404
Senjyu T, Enomoto H, Matsuno T, Matsui S (2006) Interannual salinity variations in the Tsushima Strait and its relation to the Changjiang discharge. J Oceanogr 62:681–692
Stockdale TN, Busalacchi AJ, Harrison DE, Seager R (1998) Ocean modeling for ENSO. J Geophys Res-Oceans 103:14325–14355
Stammer D, Ueyoshi K, Köhl A, Large WG, Josey SA, Wunsch C (2004) Estimating air-sea fluxes of heat, freshwater, and momentum through global ocean data assimilation. J Geophys Res-Oceans 109:C05023. doi: 10.1029/2003JC002082
Su J (2004) Overview of the South China Sea circulation and its influence on the coastal physical oceanography outside the Pearl River Estuary. Cont Shelf Res 24:1745–1760
Takikawa T, Yoon J-H (2005) Volume Transport through the Tsushima Straits Estimated from Sea Level Difference. J Oceanogr 61:699–708
Teague WJ, Jacobs GA, Ko DS, Tang TY, Chang K-I, Suk M-S (2003) Connectivity of the Taiwan, Cheju, and Korea straits. Cont Shelf Res 23:63–77
Thompson PD (1957) Uncertainty of the initial state as a factor in the predictability of large scale atmospheric flow patterns. Tellus 9:275–295
Toulany B, Garrett C (1984) Geostrophic control of fluctuating barotropic flow through straits. J Phys Oceanogr 14:649–655
Tsujino H, Nakano H, Motoi T (2008) Mechanism of currents through the straits of the Japan Sea: mean state and seasonal variation. J Oceanogr 64:141–161
Wyrtki K (1961) Physical Oceanography of the Southeast Asian Waters, vol. 2. Scripps Institute of Oceanography, University of California, La Jolla, 195 p
Xue Y, Huang B, Hu ZZ, Kumar A, Wen C, Behringer D, Nadiga S (2011) An assessment of oceanic variability in the NCEP climate forecast system reanalysis. Clim Dyn 37:2511–2539
Yuan D, Han W, Hu D (2006) Surface Kuroshio path in the Luzon Strait area derived from satellite remote sensing data, J Geophys Res-Oceans 111:C11007. doi: 10.1029/2005JC003412
Yu T, Deng Z, Han G, Wu X, Fu H, Wu K (2012) The Reanalysis of Currents and Throughflow Volume Transport in the Taiwan Strait. Marine Geod 35:16–31
Zhao W, Hou YJ, Qi P, Le KT, Li MK (2009) The effects of monsoons and connectivity of South China Sea on the seasonal variations of water exchange in the Luzon Strait, J Hydrodyn 21:264–270. doi: 10.1016/S1001-6058(08)60144-4
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Seo, GH., Choi, BJ., Cho, YK. et al. Evaluation of a regional ocean reanalysis system for the East Asian Marginal Seas based on the ensemble Kalman filter. Ocean Sci. J. 50, 29–48 (2015). https://doi.org/10.1007/s12601-015-0003-7
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DOI: https://doi.org/10.1007/s12601-015-0003-7