Observational and model studies of synoptic current fluctuations in the Bohai Strait on the Chinese continental shelf
Three winter storms struck the Bohai and Yellow seas in succession during February 16–25, 2017. Periodic fluctuations of sea level, currents, temperature, and salinity were recorded at a moored station deployed in the Bohai Strait. Observations also captured significant synoptic fluctuations of inflow and outflow through the Bohai Strait with maximum magnitude exceeding 50 cm s−1. The sea level dropped by > 1 m and the bottom temperature decreased by 2.5 °C in < 30 h during these winter storms. A regional ocean model was used to investigate the prominent fluctuations of synoptic exchange flow through the Bohai Strait. The model results indicated that the Bohai and Yellow seas in their entirety responded strongly to the storm bursts and subsequent relaxation at the synoptic scale. The periodic winter storm bursts and relaxation excited the cyclonic propagation of coastal-trapped waves around the Bohai and Yellow seas. Strong periodic inflow and outflow during the passage of the three successive storms promoted water exchange between the Bohai Sea and the northern Yellow Sea. Successive winter storms might also affect the mean current structure through the Bohai Strait. The mean currents through the Bohai Strait during the studied storm period were characterized by inflow in both northern and southern parts of the strait and outflow through the middle of the strait. This arrangement is different from the traditional view of inflow via the northern channel and outflow through the southern channel.
KeywordsBohai Strait Synoptic fluctuation Inflow and outflow Winter storm Water exchange Coastal-trapped wave
We thank the Data and Simulation Center of the Physical Oceanography Laboratory, Ocean University of China, for providing super computers for all the model simulations. We thank Data Support of the National Marine Science Data Center (Dalian), National Science & Technology Resource Sharing Service Platform of China (http://odc.dlou.edu.cn/). We thank the National Marine Data and Information Service of China, University of Hawaii Sea Level Center, global model of Estimating the Circulation and Climate of the Ocean Phase II, National Center for Environmental Prediction (NCEP), OSU Tidal Data Inversion, and Bureau of Hydrology, Ministry of Water Resources of P. R. China for providing valuable data. We thank all the crew of Dongfanghong2 for the valuable mooring data from the Bohai Strait. We also thank the three reviewers for carefully reviewing the manuscript and providing valuable suggestions. We thank James Buxton MSc from Liwen Bianji, Edanz Group China (http://www.liwenbianji.cn/ac), for editing the English text of this manuscript.
XB and ZY designed the model experiments; YD and CB carried out the model experiments; KW, MB, and CB analyzed the model results; ZJ, JS, and JG analyzed the observational data; and YD and ZY wrote the manuscript.
This work was jointly supported by the National Natural Science Foundation of China (grants 41430963, 41876006, 41676004, 41506012, 41506027), National Program on Global Change and Air–Sea Interaction (No. GASI–GEOGE 03), National Fund Committee-Shandong joint fund (No. U1706215), and National Key Research and Development Program of China (No. 2017YFC1404700).
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