scholarly journals Internal Tides and Their Intraseasonal Variability on the Continental Slope Northeast of Taiwan Island Derived from Mooring Observations and Satellite Data

2021 ◽  
Vol 14 (1) ◽  
pp. 59
Author(s):  
Yuqi Yin ◽  
Ze Liu ◽  
Yuanzhi Zhang ◽  
Qinqin Chu ◽  
Xihui Liu ◽  
...  
Keyword(s):  
Continental Slope ◽  
Satellite Data ◽  
Bottom Topography ◽  
Intraseasonal Variability ◽  
Mesoscale Eddies ◽  
Kuroshio Current ◽  
Internal Tides ◽  
Taiwan Island ◽  
The Impact ◽  
The Kuroshio

In this study, strong internal tides were observed on the continental slope northeast of Taiwan Island. Owing to the lack of long-term observations, these tides’ intraseasonal variability and the impact of the Kuroshio Current remain unclear. This study aimed to fill in the gaps using one-year continuous mooring observations, satellite data and analysis data. The horizontal kinetic energy (HKE) of semidiurnal internal tides showed that there was conspicuous energy from 100 days to 200 days, which was mainly attributed to the cross-term of HKE. The impact of the Kuroshio Current and mesoscale eddies on the HKEs were assessed: Cyclonic (anticyclonic) mesoscale eddies propagated from the open ocean, weakened (strengthened) the Kuroshio and shifted the Kuroshio onshore (offshore) northeast of Taiwan Island. The weakened (strengthened) Kuroshio increased (decreased) the shoreward velocity at the mooring site, and the onshore (offshore) Kuroshio migration increased (decreased) the northeastward velocity and enhanced (weakened) the HKEs of internal tides by modulating the tidal energy horizontal propagation. The weakened (strengthened) Kuroshio also resulted in gentler (steeper) isopycnals across the slope and enhanced (weakened) the HKEs of internal tides by influencing the interaction between ocean stratification and bottom topography.

scholarly journals Variation of Internal Tides on the Continental Slope of the Southeastern East China Sea

2022 ◽  
Vol 10 (1) ◽  
pp. 104
Author(s):  
Bing Yang ◽  
Po Hu ◽  
Yijun Hou
Keyword(s):  
Continental Slope ◽  
East China Sea ◽  
Kuroshio Current ◽  
Internal Tides ◽  
East China ◽  
Altimeter Data ◽  
China Sea ◽  
Second Mode ◽  
Variance Contribution ◽  
The Kuroshio

The semidiurnal internal tides (ITs) on the continental slope of the southeastern East China Sea (ECS) exhibited abrupt enhancement in November of 2017. This enhancement resulted from the intensification of the coherent semidiurnal ITs. Coherent and incoherent semidiurnal ITs had a comparative energy contribution in October; however, coherent semidiurnal ITs dominated with a variance contribution of 90% in November. The variance contribution of vertical modes of the semidiurnal ITs varied between October and November, and the mode with most variance contribution changed from the second mode to the first mode. Altimeter data and the observed background currents indicated that the Kuroshio mainstream meandered and abruptly intruded into the ECS in November. The upper layer background currents were significantly related to the kinetic energy of the semidiurnal ITs, and the correlation coefficient between them reached 0.81. The frequent occurrences of the Kuroshio intrusion have suggested that the ITs in the ECS are susceptible to the modulation of the Kuroshio current. Numerical modeling and predication of ITs should consider the meander of the Kuroshio mainstream.

scholarly journals Influence of the summer deep-sea circulations on passive drifts among the submarine canyons in the northwestern Mediterranean Sea

Ocean Science ◽  
2019 ◽  
Vol 15 (6) ◽  
pp. 1745-1759 ◽  
Author(s):  
Morane Clavel-Henry ◽  
Jordi Solé ◽  
Miguel-Ángel Ahumada-Sempoal ◽  
Nixon Bahamon ◽  
Florence Briton ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Continental Slope ◽  
Deep Sea ◽  
Particle Transport ◽  
Bottom Topography ◽  
Regional Ocean Modeling System ◽  
Submarine Canyons ◽  
Northwestern Mediterranean Sea ◽  
The Impact ◽  
Northwestern Mediterranean

Abstract. Marine biophysical models can be used to explore the displacement of individuals in and between submarine canyons. Mostly, the studies focus on the shallow hydrodynamics in or around a single canyon. In the northwestern Mediterranean Sea, knowledge of the deep-sea circulation and its spatial variability in three contiguous submarine canyons is limited. We used a Lagrangian framework with three-dimensional velocity fields from two versions of the Regional Ocean Modeling System (ROMS) to study the deep-bottom connectivity between submarine canyons and to compare their influence on the particle transport. From a biological point of view, the particles represented eggs and larvae spawned by the deep-sea commercial shrimp Aristeus antennatus along the continental slope in summer. The passive particles mainly followed a southwest drift along the continental slope and drifted less than 200 km considering a pelagic larval duration (PLD) of 31 d. Two of the submarine canyons were connected by more than 27 % of particles if they were released at sea bottom depths above 600 m. The vertical advection of particles depended on the depth where particles were released and the circulation influenced by the morphology of each submarine canyon. Therefore, the impact of contiguous submarine canyons on particle transport should be studied on a case-by-case basis and not be generalized. Because the flows were strongly influenced by the bottom topography, the hydrodynamic model with finer bathymetric resolution data, a less smoothed bottom topography, and finer sigma-layer resolution near the bottom should give more accurate simulations of near-bottom passive drift. Those results propose that the physical model parameterization and discretization have to be considered for improving connectivity studies of deep-sea species.

scholarly journals Assessing the impact of the Kuroshio Current on vertical cloud structure using CloudSat data

2018 ◽  
Vol 18 (10) ◽  
pp. 7657-7667 ◽  
Author(s):  
Akira Yamauchi ◽  
Kazuaki Kawamoto ◽  
Atsuyoshi Manda ◽  
Jiming Li
Keyword(s):  
Vertical Structure ◽  
Rainfall Intensity ◽  
Kuroshio Current ◽  
Cloud Layer ◽  
Frequency Of Occurrence ◽  
Surrounding Areas ◽  
The Impact ◽  
The Kuroshio ◽  
Precipitating Clouds ◽  
Geometric Thickness

Abstract. This study analyzed CloudSat satellite data to determine how the warm ocean Kuroshio Current affects the vertical structure of clouds. Rainfall intensity around the middle troposphere (6 km in height) over the Kuroshio was greater than that over surrounding areas. The drizzle clouds over the Kuroshio have a higher frequency of occurrence of geometrically thin (0.5–3 km) clouds and thicker (7–10 km) clouds compared to those around the Kuroshio. Moreover, the frequency of occurrence of precipitating clouds with a geometric thickness of 7 to 10 km increased over the Kuroshio. Stronger updrafts over the Kuroshio maintain large droplets higher in the upper part of the cloud layer, and the maximum radar reflectivity within a cloud layer in non-precipitating and drizzle clouds over the Kuroshio is higher than that around the Kuroshio.

scholarly journals Variability of Kuroshio Surface Axis Northeast of Taiwan Island Derived from Satellite Altimeter Data

2020 ◽  
Vol 12 (7) ◽  
pp. 1059
Author(s):  
Zhanpeng Zhuang ◽  
Quanan Zheng ◽  
Xi Zhang ◽  
Guangbing Yang ◽  
Xinhua Zhao ◽  
...  
Keyword(s):  
Altimeter Data ◽  
Spatial And Temporal Variability ◽  
Satellite Altimeter ◽  
Straight Path ◽  
Typical Period ◽  
Taiwan Island ◽  
The Impact ◽  
The Kuroshio ◽  
Satellite Altimeter Data ◽  
Kuroshio Axis

The spatial and temporal variability of the Kuroshio surface axis northeast of Taiwan Island is investigated using 24 years of surface geostrophic currents derived from satellite altimeter data from 1993 to 2016. The Kuroshio surface axis is derived by an extraction method with three selected parameters, including the length of the subsidiary line, the intervals between two adjacent points, and the distance between the two adjacent subsidiary lines. The empirical mode decomposition analysis on the 24-year Kuroshio axes reveals that the mean periods of intra-seasonal and inter-annual variability, which are the two dominant components, are about 3.2 months and 1.3 years, respectively. The self-organizing map analysis reveals that the variation of Kuroshio axis northeast of Taiwan Island has four best matching unit (BMU) patterns: straight-path (BMUS), meandering-path (BMUM) and two transition stages (BMUT1 and BMUT2). The straight-path pattern shows strong seasonality: more likely occurring in summer. The meandering-path pattern is less frequent than straight-path pattern. During a typical period from November 26, 2012 to January 27, 2013, which is chosen as an independent example, the analysis on the satellite altimeter and sea surface temperature data shows that the patterns of the Kuroshio axis change successively in order of BMUT1→BMUM→BMUT2→BMUS, i.e., the Kuroshio axis migrates from the meandering-path to the straight-path pattern. During the typical period the warm water intrusion and a mesoscale eddy occur at the second stage corresponding to BMUM and migrate northwestward gradually at the last two stages corresponding to BMUT2 and BMUS. The transient order appears only during this typical period but it is not common for the whole study period. The monthly mean relatively vorticity is calculated and analyzed to evaluate the impact of the eddies on the Kuroshio surface axis variability, the results show that the anticyclonic (cyclonic) eddies can promote the Kuroshio surface axis to present the meandering-path (straight-path) pattern because of the potential vorticity conservation. The impacts of the anticyclonic eddies and the cyclonic eddies on the variability of the Kuroshio surface axis are opposite. The long-term day-to-day detection contributes to improving understanding the variability of Kuroshio surface axis northeast of Taiwan Island.

scholarly journals Intraseasonal Variability of the Kuroshio at 18°N Observed by Mooring Array in 2018-2020

2021 ◽  
Author(s):  
Xin Yuan ◽  
Qingye Wang ◽  
Jie Ma ◽  
Shijian Hu ◽  
Dunxin Hu
Keyword(s):  
Current Velocity ◽  
Intraseasonal Variability ◽  
Propagation Speed ◽  
Kuroshio Current ◽  
Volume Transport ◽  
Direct Measurements ◽  
First Time ◽  
The Kuroshio ◽  
Kuroshio Transport

Abstract Based on direct measurements of the Kuroshio current velocity at 18°N by an array of three moorings from January 2018 to February 2020, the intraseasonal variability (ISV) of the Kuroshio and possible dynamic mechanism are studied. The Kuroshio transport in the upper 350m between 122.7°E and 123.3°E is estimated to be 6.5 Sv ± 2.6 Sv. It is revealed for the first time that both the current velocity and volume transport the Kuroshio at 18°N have a significant 50-60-day ISV, which contributes to over 30% of the total variance. Further analysis indicates the ISV of the Kuroshio is caused by the westward propagating eddies with a wavelength of about 633 km and a propagation speed of about 13 cm/s. In addition, the transport mode (74.2%) of the Kuroshio at 18°N is dominant, rather than the migration mode (11.6%). That is different from the Kuroshio east of Taiwan. The findings of this study will highlight the important role of westward Rossby waves (eddies) with a finite wavelength in modulating the intraseasonal variability of the Kuroshio transport near its origin.

scholarly journals Effects of Mesoscale Eddies On Intraseasonal Variability of Intermediate Water East of Taiwan

2022 ◽  
Author(s):  
Qiang Ren ◽  
Fei Yu ◽  
Feng Nan ◽  
Yuanlong Li ◽  
Jianfeng Wang ◽  
...  
Keyword(s):  
Intermediate Layer ◽  
Intraseasonal Variability ◽  
Correlation Coefficients ◽  
Mesoscale Eddies ◽  
Vertical Movement ◽  
Intermediate Water ◽  
Sea Level Anomalies ◽  
Anticyclonic Eddies ◽  
Counter Current ◽  
The Kuroshio

Abstract The variability of intermediate water (IW) east of Taiwan was investigated utilizing 17 months of long-term, continuous and synchronous measurements of temperature, salinity and current from mooring sites deployed at 122ºE/23ºN from January 2016 to May 2017. For the first time, we prove that the intraseasonal variability in the IW within significant periods of ~80 days was caused by mesoscale eddies propagating westward from the Subtropic Counter Current (STCC) area. The correlation coefficients between sea level anomalies (SLAs) and the Kuroshio, and between SLAs and the minimum salinity in the intermediate layer, were 0.63 and 0.52, respectively. The anticyclonic (cyclonic) eddies from the STCC, increased (decreased) the speed of the Kuroshio as well as increase (decrease) the temperature and salinity in the 400–600 m in east of Taiwan. Combines Archiving, Validation and Interpretation of Satellite Oceanographic (AVISO) products data, showed that temperature and salinity increased (decreased) in the intermediate layer due to the downward (upward) vertical movement of the water mass by anticyclonic (cyclonic) eddies. Anticyclonic eddies strengthened the Kuroshio and benefitted SCSIW flowing through the Luzon Strait to enhance salinity, while cyclonic eddies weakened the Kuroshio and favored relatively low-salt NPIW, in the area east of Taiwan.

Spatial-temporal variability of M2 internal tides modulated by the Kuroshio currents and mesoscale eddies northeast of Taiwan

2020 ◽  
Author(s):  
Hang Chang ◽  
Yahao Liu
Keyword(s):  
High Resolution ◽  
Temporal Variability ◽  
Internal Tide ◽  
Mesoscale Eddies ◽  
Vertical Displacement ◽  
Internal Tides ◽  
Time Varying ◽  
Energy Beam ◽  
Continental Slopes ◽  
The Kuroshio

<p>The spatial-temporal variability and energetics of M2 internal tides during their generation and propagation through the Kuroshio flows and robust eddies northeast of Taiwan are investigated using a high-resolution numerical model. The corrugated continental slopes, particularly the I-Lan Ridge and Mien-Hua Canyon, are identified as the energetic sources of M2 internal tides. The M2 internal tide generation is influenced by the horizontally varying and zonally tilting stratification associated with the Kuroshio currents and mesoscale eddies. In this situation, the magnitude of conversion rate and energy beam exhibit highly temporal variability. An energetic along-slope tidal beam from the I-Lan Ridge radiates southward against the northward Kuroshio flows, causing strong vertical displacement. Complex background currents lead to the time-varying inhomogeneous diapycnal mixing induced by internal tide dissipation.</p>

scholarly journals Assessing the impact of the Kuroshio Current on vertical cloud structure using CloudSat data

2018 ◽  
Author(s):  
Akira Yamauchi ◽  
Kazuaki Kawamoto ◽  
Atsuyoshi Manda ◽  
Jiming Li
Keyword(s):  
Vertical Structure ◽  
Rainfall Intensity ◽  
Kuroshio Current ◽  
Cloud Layer ◽  
Frequency Of Occurrence ◽  
Surrounding Areas ◽  
The Impact ◽  
The Kuroshio ◽  
Precipitating Clouds ◽  
Geometric Thickness

Abstract. This study analysed CloudSat satellite data to determine how the warm ocean Kuroshio Current affects the vertical structure of clouds. Rainfall intensity around the middle troposphere (6 km in height) over the Kuroshio was greater than that over surrounding areas. The drizzle clouds over the Kuroshio have a higher frequency of occurrence of geometrically thin (0.5–3 km) clouds and thicker (7–10 km) clouds compared to those around the Kuroshio. Moreover, the frequency of occurrence of precipitating clouds with a geometric thickness of 7 to 10 km increased over the Kuroshio. Stronger updraft over the Kuroshio maintains large droplets higher in the upper part of the cloud layer, and the maximum radar reflectivity within a cloud layer in non-precipitating and drizzle clouds over the Kuroshio is higher than that around the Kuroshio.

scholarly journals Environmental influences on sinking rates and distributions of transparent exopolymer particles after a typhoon surge at the Western Pacific

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Shahanul Islam ◽  
Jun Sun ◽  
Guicheng Zhang ◽  
Zhuo Chen ◽  
Hui Zhou
Keyword(s):  
Water Layer ◽  
Kuroshio Current ◽  
Western Pacific ◽  
Transparent Exopolymer Particles ◽  
Chl A ◽  
Bottom Water Layer ◽  
Regression Curves ◽  
The Impact ◽  
The Kuroshio ◽  
The Western Pacific

AbstractA multidisciplinary approach was used to investigate the causes of the distributions and sinking rates of transparent exopolymer particles (TEPs) during the period of September–October (2017) in the Western Pacific Ocean (WPO); the study period was closely dated to a northwest typhoon surge. The present study discussed the impact of biogeophysical features on TEPs and their sinking rates (sTEP) at depths of 0–150 m. During the study, the concentration of TEPs was found to be higher in areas adjacent to the Kuroshio current and in the bottom water layer of the Mindanao upwelling zone due to the widespread distribution of cyanobacteria, i.e., Trichodesmium hildebrandti and T. theibauti. The positive significant regressions of TEP concentrations with Chl-a contents in eddy-driven areas (R2 = 0.73, especially at 100 m (R2 = 0.75)) support this hypothesis. However, low TEP concentrations and TEPs were observed at mixed layer depths (MLDs) in the upwelling zone (Mindanao). Conversely, high TEP concentrations and high sTEP were found at the bottom of the downwelling zone (Halmahera). The geophysical directions of eddies may have caused these conditions. In demonstrating these relations, the average interpretation showed the negative linearity of TEP concentrations with TEPs (R2 = 0.41 ~ 0.65) at such eddies. Additionally, regression curves (R2 = 0.78) indicated that atmospheric pressure played a key role in the changes in TEPs throughout the study area. Diatoms and cyanobacteria also curved the TEPs significantly (R2 = 0.5, P < 0.05) at the surface of the WPO. This study also revealed that TEP concentration contributes less to the average particulate organic carbon in this oligotrophic WPO.

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