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Oceanographic Factors
Published in Ronald C. Chaney, Marine Geology and Geotechnology of the South China Sea and Taiwan Strait, 2020
The North Pacific general circulation pattern of surface waters is deflected to the right and pushed toward the interior of the mid-Pacific gyre, where a high pressure zone is maintained. This is due to the trade winds that blow between 30° north latitude and the equator. This movement of surface waters establishes a major, westward flowing geostrophic current, the North Equatorial Current. The current reaches the western margin of the North Pacific Basin, where land masses deflect it towards the north. There it merges with a portion of the Kuroshio Current, which has been deflected to the north by the Philippines. The combined current moves along the east coast of the Philippines, Taiwan, and Japan as the Kuroshio Current. The Kuroshio Current then merges with the North Pacific current, which in turn merges with the California current along the west coast of North America.
Measurement of the North Equatorial Current/Undercurrent by a subsurface mooring at 160°E
Published in Journal of Operational Oceanography, 2021
Jiahao Wang, Xi Chen, Kefeng Mao
The North Equatorial Current (NEC) which is driven by the trade wind flows westward stably and connects subtropical with tropical gyres in the North Pacific Ocean. It transports water into the western tropical Pacific and contributes to the establishment of tropical warm pools and the Northern Hemisphere climate (Dunxin and Maochang 1991; Clement et al. 2005; Hu et al. 2015; Omrani et al. 2019; Park et al. 2019). Many oceanographers have investigated the NEC’s characteristics and variability at intraseasonal, seasonal, interannual and decadal time scales based on in situ observations (Wang and Hu 2006; Kashino et al. 2009; Wang et al. 2009; Zhai and Hu 2012; Zhai et al. 2013; Hu and Hu 2014; Schönau and Rudnick 2015; Zhang et al. 2017; Wang et al. 2019), numerical model simulations (Qiu and Lukas 1996; Chen and Wu 2011; Jensen 2011; Ju et al. 2013; Zhai et al. 2014a; Zhai et al. 2014b) and ocean reanalyzes (Meng et al. 2011; Chen and Wu 2012; Zhai and Hu 2013; Yan et al. 2014, Zhai et al. 2014a, Zhao et al. 2015; Wu et al. 2016; Zhai et al. 2018). Beneath the NEC, the intermittent North Equatorial Undercurrents (NEUC) which originates in annual baroclinic Rossby waves driven by the large-scale surface wind stress forcing flows in reverse (Qiu, Chen et al. 2013). Using in situ measurements (Toole et al. 1988; Dutrieux 2009; Qiu, Chen et al. 2013; Zhang et al. 2017; Ishizaki et al. 2019) and model simulations (Qiu, Rudnick et al. 2013; Li et al. 2018), oceanographers investigate the NEUC.
On the radius of spatial analyticity for Ostrovsky equation with positive dispersion
Published in Applicable Analysis, 2022
We consider the radius of spatial analyticity for the Ostrovsky equation with positive dispersion where u represents the free surface of a liquid and the positive parameter γ measures the effect of rotation. This Equation (1) was proposed by Ostrovsky [1] as a model for weakly nonlinear long waves in a rotating liquid, by taking into account of the Coriolis force. The Ostrovsky equation describes the propagation of surface and internal waves in the ocean in a rotating frame of reference. These unidirectional propagating waves in the ocean under the presentation of rotation, for example equatorial ocean current, have impacts on fisheries and climate. Controlled by the trade wind, the ocean current near the equator forms two westward-flowing currents, North Equatorial Current (NEC) and South Equatorial Current (SEC); within the doldrums, the eastward Equatorial Countercurrent passes between the NEC and SEC; the Equatorial Undercurrent in the thermocline keeps constant eastward flowing against the NEC and SEC. Research on such waves has important physical significance [2,3]. In Equation (1), β determines the type of dispersion, more precisely, (negative dispersion) for surface and internal waves in the ocean or surface waves in a shallow channel with an uneven bottom, and (positive dispersion) for capillary waves on the surface of a liquid or for oblique magneto-acoustic waves in plasma [4–9]. The Cauchy problem of the Ostrovsky Equation (1) has also been examined [10–17]. The results in [13,15,18] showed that is the critical regularity index for Equation (1) in Sobolev spaces. Recently, Yan et al. [19] proved that the Cauchy problem for the Ostrovsky equation with positive dispersion is locally well posed in .