Research papers Volume transport through the Taiwan Strait and the effect of synoptic events Wen-Zhou Zhang a,b,c,n , Fei Chai d , Hua-Sheng Hong a,b , Huijie Xue d a State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China b Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, China c Key Laboratory of Underwater Acoustic Communication and Marine Information Technology (Xiamen University), Ministry of Education, Xiamen, China d School of Marine Sciences, University of Maine, Orono, ME, USA article info Article history: Received 24 January 2014 Received in revised form 21 July 2014 Accepted 22 July 2014 Available online 2 August 2014 Keywords: Volume transport Typhoon Taiwan Strait Numerical model abstract Volume transport through the Taiwan Strait during 2005–2008 was simulated using a shallow water model forced by high spatio-temporal resolution meteorological data. On average, simulated monthly mean transports ranged from a southward maximum of 0.38 Sv in December to a northward maximum of 2.02 Sv in June, with an annual mean northward transport of 0.78 Sv. These estimates are in agreement with the published results based on bottom-mounted ADCP observations. Several sensitivity experiments were conducted to separately examine possible influence of ignoring air pressure or applying time-averaged wind forcing on the transport estimate. We found that excluding the air pressure component in the model gave rise to an insignificant difference (0.01 Sv) in the mean transport estimate. Using multi-year-averaged monthly mean wind, however, provided markedly different results; it brought about a magnitude change of up to 0.65 Sv for the monthly mean transport and 0.34 Sv for the annual mean transport. The nonlinear parameterization of wind stress was mainly responsible for the distortion. In addition, we found that typhoons, as one kind of synoptic events, had an accumulative influence not only on the monthly mean transport during the typhoon season but also on the annual mean transport. The effect of typhoons reduced the monthly mean transport by up to 0.45 Sv and the annual mean transport by 0.09 Sv (more than 10%). Therefore, high temporal resolution wind data with synoptic scale variability are required to accurately estimate the monthly mean and annual mean transports when using a model. & 2014 Elsevier Ltd. All rights reserved. 1. Introduction The Taiwan Strait is a wide (average 180 km) and long (about 350 km) channel oriented along the southwest-northeast direc- tion. It connects two large marginal seas in the western North Pacific—the South China Sea to the south and the East China Sea to the north (Fig. 1). It is a unique, direct passage for water exchange, energy transfer and nutrient flux between the two seas (Liu et al., 2000; Chung et al., 2001). Since an accurate estimate of volume transport through the strait is a prerequisite for clarifying material exchange, many investigations have been conducted intermit- tently since the 1960s (e.g., Wyrtki, 1961; Fu et al., 1991; Chai et al., 2001; Jan et al., 2006; Wang et al., 2009). Based on the sea level measurements at an imperfect pair of stations located on both sides of the Taiwan Strait and the geostrophic assumption in the cross-strait direction, Wyrtki (1961) reckoned that the transport through the strait is less than 1 Sv (positive for northward and negative for southward, similarly hereinafter) even in July and December when the currents in the strait are strong, and that the transport direction is northward in summer but southward in winter. The results calculated directly from limited current observations taken by survey ships indicated that the transport is always northward, and its magnitude is 3.32 Sv in summer and 1.74 Sv in winter (Fu et al., 1991). Using more current observations by anchored moorings from ships and moored current meters at a few sites in the strait, Fang et al. (1991) obtained similar results of 3.1 Sv in summer and 1.0 Sv in winter, with an annual mean transport of 2 Sv. From the current measure- ments by shipboard Acoustic Doppler Current Profiler (sb-ADCP) during two survey periods of 23–25 May and 13–14 August 1999, Chung et al. (2001) estimated that the transports in May and August are 2.0 and 2.2 Sv, respectively. Later on, more cruise data Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/csr Continental Shelf Research http://dx.doi.org/10.1016/j.csr.2014.07.010 0278-4343/& 2014 Elsevier Ltd. All rights reserved. n Corresponding author at: College of Ocean and Earth Sciences, Xiamen University Xiamen, Xiamen 361005, Fujian, China. Tel.: þ86 592 2184209; fax: þ86 592 2095242. E-mail address: zwenzhou@xmu.edu.cn (W.-Z. Zhang). Continental Shelf Research 88 (2014) 117–125