Surface currents measured by GPS drifters in Daya Bay and along the eastern Guangdong coast

Abstract

GPS-based surface drifters were used to investigate the surface currents in Daya Bay and along the eastern Guangdong coast in China. Surface current vectors were measured based on the GPS location and corresponding time information sent by drifters through the mobile phone network. The analysis of data from 120 drifters, deployed in late spring 2018 in the case-study region, shows that the drifters are generally capable of capturing the surface (tidal and residual) currents. The drifter trajectories suggest an anticlockwise surface current inside Daya Bay and a north-eastward current along the eastern Guangdong coast, where the coastal current along the eastern Guangdong coast is faster than that inside Daya Bay. The surface currents in the investigated region follow an irregular semidiurnal cycle due to the influence of the tidal current, while the currents inside Daya Bay are strongly affected by the topography. According to the harmonic analysis, an irregular semidiurnal type of tidal current is evident at a study grid inside Daya Bay, with an Eulerian residual current speed of 9.0 cm/s and a direction of 276°. The Lagrangian residual current outside Daya Bay moves north-eastward with a mean speed of 22 cm/s along the eastern Guangdong coast, while the current inside Daya Bay moves northward to the bay head with a mean speed of about 8.0 cm/s, which agrees well with the one reported in other literatures.

Keywords

drifter / surface current / residual current / Daya Bay / eastern Guangdong coast

References

[1] Awaji T, Imasato N, Kunishi H (1980). Tidal exchange through a strait: a numerical experiment using a simple model basin. J Phys Oceanogr, 10(10): 1499–1508

[2] Centurioni L R (2018). Drifter technology and impacts for sea surface temperature, sea-level pressure, and ocean circulation studies. In: Observing the Oceans in Real Time. Cham: Springer International Publishing, Cham, 37–57

[3] Chen Z F, Li X F, Zhang J, Li H (2009). Pseudospectral method calculation of tidal field and particle random walk simulation of radionuclides in Daya Bay. Radiation Protection, 29(6): 363–370 (in Chinese)

[4] Chen Z Y (1980). Tidology. Beijing: Science Press, 301

[5] David L T A (1995). The tropical ocean global atmosphere program. Contemp Phys, 36(4): 245–265

[6] Kells L M, Kern W F, Bland J R (1940). Plane and Spherical Trigonometry. New York: McGraw Hill Book Company, 323–326

[7] Lin H Y, Sun Z Y, Chen Z Z, Zhu J, Hu J Y (2019). Wintertime Guangdong coastal currents successfully captured by cheap GPS drifters. Acta Oceanol Sin, (1–5)

[8] Muller H, Blanke B, Dumas F, Lekien F, Mariette V (2009). Estimating the Lagrangian residual circulation in the Iroise Sea. J Mar Syst, 78(4): 17–36

[9] Nasello C, Armenio V (2016). A new small drifter for shallow water basins: Application to the study of surface currents in the Muggia Bay (Italy). J Sens, 1(14): 1–5

[10] Pawlowicz R B, Beardsley B, Lentz S (2002). Classical tidal harmonic analysis including error estimates in MATLAB using T_TIDE. Comput Geosci, 28(8): 929–937

[11] Perez J C, Bonner J, Kelly F J, Fuller C (2003). Development of a cheap, GPS-based, radio-tracked, surface drifter for closed shallow-water bays. Current measurement technology, Proceedings of the IEEE/OES Seventh Working Conference on. IEEE: 66–69

[12] Prasad S J, Nair T M B, Rahaman H, Joseph S, Yatin G (2017). Evaluation of oil spill trajectory model with the observed SVP drifter track

[13] Qiu Y, Li L, Chen C T A, Guo C G, Jing C S (2011). Currents in the Taiwan Strait as observed by surface drifters. J Oceanogr, 67(4): 395–404

[14] Schmidt W E, Woodward B T, Millikan K S, Guza R T, Raubenheimer B, Elgar S (2003). A GPS-tracked surf zone drifter. J Atmos Ocean Technol, 20(7): 1069–1075

[15] Tseng R S, Chang Y C, Chu P C (2017). Use of global satellite altimeter and drifter data for ocean current resource characterization. In: Yang Z Q, Copping A eds. Marine Renewable Energy. Springer International Publishing AG, 159–177

[16] Wu R H, Cai S Q, Wang S A, Zhang W K (2007). Three-dimensional numerical simulation of tidal current and residual current at Daya Bay. Journal of Tropical Oceanography, 26(3): 18–23 (in Chinese)

[17] Wu W, Yan J H, Song D H (2017). Study on the tidal dynamics in Daya Bay, China-Part I. Observation and numerical simulation of tidal dynamic system. Journal of Tropical Oceanography, 36(3): 34–45 (in Chinese)

[18] Xu G Z (1989). The characteristics of tidal current and residual current. In: Wang C Y, eds. The Environment and Resource of the Daya Bay. Hefei: Anhui Science & Technology Publishing House, 10–14

[19] Xu J D, Zeng G (1991). Analysis of winter current fluctuation in Daya Bay. J Oceanogr Taiwan, 10(1): 33–38 (in Chinese)

[20] Yang G B (2001). The characteristics of tidal current in the Daya Bay area. Pearl River, (1): 30–32 (in Chinese)

Acknowledgments

This work was supported by the National Natural Science Foundation of China (Grant Nos. 91958203, 41776027, and 41606009), the Xiamen University Fundamental Research Funds for the Central Universities (Nos. 20720180103, 20720180099), the Laboratory for Regional Oceanography and Numerical Modeling, Pilot National Laboratory for Marine Science and Technology (Qingdao) (No. 2017A02) and the municipal project of Huizhou City (No. F2017-01-1). All the cruise participants are appreciated. We also thank three anonymous reviewers and the Editor for insightful comments that help to improve the manuscript.

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