Cross Flows in the Taiwan Strait in Winter*

2014 ◽  
Vol 44 (3) ◽  
pp. 801-817 ◽  
Author(s):  
L.-Y. Oey ◽  
Y.-L. Chang ◽  
Y.-C. Lin ◽  
M.-C. Chang ◽  
S. Varlamov ◽  
...  

Abstract In winter, a branch of the China Coastal Current can turn in the Taiwan Strait to join the poleward-flowing Taiwan Coastal Current. The associated cross-strait flows have been inferred from hydrographic and satellite data, from observed abundances off northwestern Taiwan of cold-water copepod species Calanus sinicus and, in late March of 2012, also from debris found along the northwestern shore of Taiwan of a ship that broke two weeks earlier off the coast of China. The dynamics related to such cross flows have not been previously explained and are the focus of this study using analytical and numerical models. It is shown that the strait’s currents can be classified into three regimes depending on the strength of the winter monsoon: equatorward (poleward) for northeasterly winds stronger (weaker) than an upper (lower) bound and cross-strait flows for relaxing northeasterly winds between the two bounds. These regimes are related to the formation of the stationary Rossby wave over the Changyun Ridge off midwestern Taiwan. In the weak (strong) northeasterly wind regime, a weak (no) wave is produced. In the relaxing wind regime, cross-strait currents are triggered by an imbalance between the pressure gradient and wind and are amplified by the finite-amplitude meander downstream of the ridge where a strong cyclone develops.

Crustaceana ◽  
2020 ◽  
Vol 93 (3-5) ◽  
pp. 487-506
Author(s):  
Yan-Guo Wang ◽  
Li-Chun Tseng ◽  
Rou-Xin Sun ◽  
Zhi-Yong Liu ◽  
Mao Lin ◽  
...  

Abstract The Taiwan Strait, located between Taiwan Island and the southeast of the mainland of China, is the main passageway connecting the East China Sea and the South China Sea. The particular coastline of the mainland created several semi-enclosed embayments along the west coast of the Taiwan Strait. Runoffs from land bring large amounts of nutrients into the bays, which made these bays important natural spawning and breeding grounds for several economically important marine organisms. In order to reveal the effects of the China Coastal Current (CCC) on the zooplankton communities in Fuqing Bay in northeastern Fujian, zooplankton samples were collected at 12 stations in early March 2014. The average surface seawater temperature was 12.53 ± 0.14°C, and salinity was 28.33 ± 0.21 PSU in the investigation area during the research period. In total, 23 identified copepod species and in addition several unidentified benthic harpacticoid copepods were recorded with an average abundance of 77.44 ± 60.07 ind. m−3. In the present study, the most dominant group consisted of juveniles (copepodites) with an average density of 59.97 ± 51.49 ind. m−3, which was followed by Calanus sinicus Brodsky, 1965 with an average density of 5.04 ± 4.95 ind. m−3. The occurrence rate of Calanus sinicus was 91.67% in our study, which indicates that the research area was controlled by the CCC water mass. So, we concluded that the CCC played an important role in transporting cold water copepod species from the Bohai Sea and the Yellow Sea to the western Taiwan Strait. A noteworthy discovery in our samples was Eurytemora pacifica Sato, 1913, which was recorded for the first time in waters of the western Taiwan Strait with an occurrence rate of 33.33% and an average density of 0.81 ± 1.91 ind. m−3. Eurytemora pacifica was first reported at Yantai harbour and is widely distributed in waters of the northern Pacific Ocean. The co-occurrence of Calanus sinicus and Eurytemora pacifica in our research area possibly indicates that E. pacifica could be used as a bioindicator for the directional movement of the CCC. The high occurrence of this species in our research area indicated that the CCC affects the community structure of copepods in the western Taiwan Strait in early spring.


2021 ◽  
Author(s):  
Yu-Kai Chen ◽  
Chia-Yi Pan ◽  
Yi-Chen Wang ◽  
Hsiu-Ju Tseng ◽  
Bo-Kun Su ◽  
...  

AbstractIn this study, the interannual variations of ichthyoplankton assemblages in the Taiwan Strait (TS) during the winters of 2007–2013 were determined. The cold China Coastal Current (CCC) and Mixed China Coastal Water (MCCW) intruded into the TS and impinged with the warm Kuroshio Branch Current (KBC) with annual variations. Consequently, the ichthyoplankton community in the TS was mainly structured into two assemblages characterized by differing environmental conditions. The composition of the warm KBC assemblage was relatively stable and was characterized by Diaphus B and Bregmaceros spp. By contrast, the cold MCCW assemblage demonstrated considerable variations over the years, with demersal Gobiidae and Scorpaenidae families considered the most representative. In addition, Benthosema pterotum and Trichiurus spp. were common in both KBC and MCCW assemblages. The distribution of the KBC assemblage demonstrated sharp boundaries in the frontal zones, whereas changes in the assemblage structure between the frontal zones were gradual for the MCCW assemblage, particularly when demersal taxa were dominant. Sea surface temperature and salinity were most strongly associated with variability in the assemblage structure during the study period. Thus, this paper provides a better understanding of long-term larval fish dynamics during winter in the TS.


2015 ◽  
Vol 8 ◽  
Author(s):  
Euichi Hirose ◽  
Mamiko Hirose ◽  
Jhy-Yun Shy

Diplosoma gumavirensspecimens were collected from the Penghu Islands, Taiwan. This is the first record of photosymbiotic ascidians in the Taiwan Strait, where the minimum water temperature in the winter is <16°C because of intrusion of the China Coastal Current.


Author(s):  
Nan-Jung Kuo ◽  
Chung-Ru Ho ◽  
Shih-Jen Huang

In this paper, we discuss the kinematic properties of the mesoscale features in the Taiwan Strait (TS). Two kinds of mesoscale features can be seen in the TS. One is the shear wave; it is a lateral wavelike train with phase speed and wave period. The other one is the eddy-like cold-water wedge; it mainly rotates with a little translation. The shear wave mainly occurs in the boundary of the China cold water along the western TS in winter and spring. The eddy-like cold-water wedge can be seen in the mid-winter when the strong southward China coastal cold water covers up most of the northern TS and creates a very unstable front with the northward warm water. In this study, selected NOAA satellite AVHRR channel 4 infrared images during 2000–2003 are considered to detect the movement of the above mesoscale features through a feature-tracking method. It is found that the development of these features is highly related to the monsoon winds. Meanwhile, the local tidal pattern can also affect their movements.


2018 ◽  
Author(s):  
Yu-Hsin Cheng ◽  
Ming-Huei Chang

Abstract. The objectives of this study were to assess the predictability of exceptionally cold water in the Taiwan Strait (TS) and to develop a warning system on the base of scientific mechanism, which is a component of the information technology system currently under development in Taiwan to protect aquaculture against extreme hazards. Optimum interpolation sea surface temperature (SST) data were used to find exceptionally cold water days from January 1995 to May 2017. We found that the SST and wind speed over the TS are low and strong in La Niña winters, respectively. According to tests conducted using relative operating characteristic curves, predictions based on the Oceanic Niño Index and integrated wind speed can be employed at lead times of 60–210 and 0–30 days, respectively. This study utilized these two proxies to develop a possible warning mechanism and concluded four colors of warning light: (1) blue, meaning normal; (2) cyan, meaning warning; (3) yellow, meaning moderate risk; and (4) red, meaning high risk. Hindcasting winters over the period 1995–2017 successfully predicted the cold water hazards in the winters of 2000, 2008, 2011, and 2012 in prior to the coldest day ~ 20 days.


2018 ◽  
Vol 18 (7) ◽  
pp. 1999-2010 ◽  
Author(s):  
Yu-Hsin Cheng ◽  
Ming-Huei Chang

Abstract. The objectives of this study were to assess the predictability of exceptionally cold water in the Taiwan Strait (TS) and to develop a warning system on the basis of the scientific mechanism, which is a component of the information technology system currently under development in Taiwan to protect aquaculture against extreme hazards. Optimum interpolation sea surface temperature (SST) data were used to find exceptionally cold water days from January 1995 to May 2017. We found that the SST and wind speed over the TS are low and strong in La Niña winters, respectively. According to tests conducted using relative operating characteristic curves, predictions based on the Oceanic Niño Index and integrated wind speed can be employed at lead times of 60–120 and 0–25 days, respectively. This study utilized these two proxies to develop a possible warning mechanism and concluded four colors of warning light: (1) blue, meaning normal (0 % occurrence probability); (2) cyan, meaning warning (∼ 50 % occurrence probability); (3) yellow, meaning moderate risk (∼ 60 % occurrence probability); and (4) red, meaning high risk (∼ 75 % occurrence probability). Hindcasting winters over the period 1995–2017 successfully predicted the cold water hazards in the winters of 2000, 2008, and 2011 prior to the coldest day by ∼ 20 days.


2018 ◽  
Vol 61 (4) ◽  
pp. 483-493 ◽  
Author(s):  
Li Li ◽  
Xiaogang Guo ◽  
Enhui Liao ◽  
Yuwu Jiang

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