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.

scholarly journals Observed Warm Filaments from the Kuroshio Associated with Mesoscale Eddies

2020 ◽  
Vol 12 (18) ◽  
pp. 3090
Author(s):  
Qian Shi ◽  
Guihua Wang
Keyword(s):  
High Frequency ◽  
Average Length ◽  
Mesoscale Eddies ◽  
Satellite Observations ◽  
Sea Surface ◽  
Large Temperature ◽  
Anticyclonic Eddies ◽  
The Kuroshio ◽  
Sst Gradient

Based on high resolution satellite observations of sea surface temperature (SST), warm filaments near the Kuroshio around the Luzon Strait were systematically identified. These filaments extend an average length of about 200 km from the Kuroshio. The occurrence and features of the warm filaments are highly associated with both mesoscale eddies and the intensity of the SST gradient of the Kuroshio. Warm filaments are formed by heat advection from the warm Kuroshio into the colder interior Pacific Ocean by anticyclonic eddies (∼58%), cyclonic eddies (∼10%), and the dipole eddies (∼16%). The large temperature gradient near the Batanes Islands may also contribute to the high frequency of warm filaments in their vicinity. This study will help elucidate the role of zonal heat transport associated with the Kuroshio–eddy interaction during filament formation.

scholarly journals Anatomy of a Cyclonic Eddy in the Kuroshio Extension Based on High-Resolution Observations

Atmosphere ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 553 ◽  
Author(s):  
Yongchui Zhang ◽  
Xi Chen ◽  
Changming Dong
Keyword(s):  
High Resolution ◽  
Mixed Layer ◽  
Kuroshio Extension ◽  
Mesoscale Eddies ◽  
Cyclonic Eddy ◽  
Intermediate Water ◽  
Dipole Structure ◽  
Significant Difference ◽  
The Kuroshio ◽  
Main Thermocline

Mesoscale eddies are common in the ocean and their surface characteristics have been well revealed based on altimetric observations. Comparatively, the knowledge of the three-dimensional (3D) structure of mesoscale eddies is scarce, especially in the open ocean. In the present study, high-resolution field observations of a cyclonic eddy in the Kuroshio Extension have been carried out and the anatomy of the observed eddy is conducted. The temperature anomaly exhibits a vertical monopole cone structure with a maximum of −7.3 °C located in the main thermocline. The salinity anomaly shows a vertical dipole structure with a fresh anomaly in the main thermocline and a saline anomaly in the North Pacific Intermediate Water (NPIW). The cyclonic flow displays an equivalent barotropic structure. The mixed layer is deep in the center of the eddy and thin in the periphery. The seasonal thermocline is intensified and the permanent thermocline is upward domed by 350 m. The subtropical mode water (STMW) straddled between the seasonal and permanent thermoclines weakens and dissipates in the eddy center. The salinity of NPIW distributed along the isopycnals shows no significant difference inside and outside the eddy. The geostrophic relation is approximately set up in the eddy. The nonlinearity—defined as the ratio between the rotational speed to the translational speed—is 12.5 and decreases with depth. The eddy-wind interaction is examined by high resolution satellite observations. The results show that the cold eddy induces wind stress aloft with positive divergence and negative curl. The wind induced upwelling process is responsible for the formation of the horizontal monopole pattern of salinity, while the horizontal transport results in the horizontal dipole structure of temperature in the mixed layer.

scholarly journals Energy Exchange between the Mesoscale Oceanic Eddies and Wind-Forced Near-Inertial Oscillations

2017 ◽  
Vol 47 (3) ◽  
pp. 721-733 ◽  
Author(s):  
Zhao Jing ◽  
Lixin Wu ◽  
Xiaohui Ma
Keyword(s):  
Energy Transfer ◽  
Energy Exchange ◽  
Kuroshio Extension ◽  
Mesoscale Eddies ◽  
Energy Transfer Efficiency ◽  
Layer Model ◽  
Strain Variance ◽  
Anticyclonic Eddies ◽  
The Kuroshio ◽  
Kuroshio Extension Region

AbstractIn this study, the energy exchange between mesoscale eddies and wind-forced near-inertial oscillations (NIOs) is theoretically analyzed using a slab mixed layer model modified by including the geostrophic flow. In the presence of strain, there is a permanent energy transfer from mesoscale eddies to NIOs forced by isotropic wind stress. The energy transfer efficiency, that is, the ratio of the energy transfer rate to the near-inertial wind work, is proportional to , where S2 is the total strain variance, is the effective Coriolis frequency, and ζ is the relative vorticity. The theories derived from the modified slab mixed layer model are verified by the realistic numerical simulation obtained from a coupled regional climate model (CRCM) configured over the North Pacific. Pronounced energy transfer from mesoscale eddies to wind-forced NIOs is localized in the Kuroshio Extension region associated with both strong near-inertial wind work and strain variance. The energy transfer efficiency in anticyclonic eddies is about twice the value in cyclonic eddies in the Kuroshio Extension region because of the influence of ζ on feff, which may contribute to shaping the dominance of cyclonic eddies than anticyclonic eddies in that region.

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 The Kuroshio East of Taiwan: Modes of Variability and Relationship to Interior Ocean Mesoscale Eddies

2001 ◽  
Vol 31 (4) ◽  
pp. 1054-1074 ◽  
Author(s):  
Dongxiao Zhang ◽  
Thomas N. Lee ◽  
William E. Johns ◽  
Cho-Teng Liu ◽  
Rainer Zantopp
Keyword(s):  
Mesoscale Eddies ◽  
Modes Of Variability ◽  
The Kuroshio

scholarly journals Evolution and Structure of the Kuroshio Extension Front in Spring 2019

2020 ◽  
Vol 8 (7) ◽  
pp. 502
Author(s):  
Jiahao Wang ◽  
Kefeng Mao ◽  
Xi Chen ◽  
Kelan Zhu
Keyword(s):  
Saline Water ◽  
Kuroshio Extension ◽  
Intermediate Water ◽  
North Pacific Intermediate Water ◽  
Water Region ◽  
Diffusive Convection ◽  
Thermohaline Intrusions ◽  
Salt Fingering ◽  
The Kuroshio ◽  
Kuroshio Extension Front

Satellite data products and high-resolution in situ observations were combined to investigate the evolution and structure of the Kuroshio Extension Front in Spring 2019. The former reveals the variation of the front is influenced by the northward movement of the Kuroshio Extension through transporting warm and saline water to a cold and brackish water region. The latter indicates steep upward slopes of the isopycnals, tilting northward in the frontal zone, as well as several ~300 m thick blobs of North Pacific Intermediate Water between 26.25 and 26.75 kg/m3, where conspicuous thermohaline intrusions occur. Further analysis indicates these thermohaline intrusions prefer to alternate salt fingering and diffusive convection interfaces, and are affected by strong shears.

scholarly journals Extraction of Revolving Channels of Drifters around Mesoscale Eddy Centers Based on Spatiotemporal Trajectory Clustering

2019 ◽  
Vol 36 (9) ◽  
pp. 1903-1916
Author(s):  
Chunyong Ma ◽  
Siqing Li ◽  
Yang Yang ◽  
Jie Yang ◽  
Ge Chen
Keyword(s):  
Clustering Algorithm ◽  
Spatial Clustering ◽  
Mesoscale Eddy ◽  
Mesoscale Eddies ◽  
Trajectory Clustering ◽  
Satellite Altimeter ◽  
Principal Mode ◽  
In Situ Data ◽  
Anticyclonic Eddies

The global oceanic transports of energy, plankton, and other tracers by mesoscale eddies can be estimated by combining satellite altimetry and in situ data. However, the revolving channels of particles entrained by mesoscale eddies, which could help explain the dynamic process of eddies entraining materials, are still unknown. In this study, satellite altimeter and drifter data from 1993 to 2016 are adopted, and the normalized trajectory clustering algorithm (N-TRACLUS) is proposed to extract the revolving channels of drifters. First, the trajectories of drifters are normalized and clustered by using the density-based spatial clustering of applications with noise (DBSCAN) algorithm. Next, the revolving channels of drifters around the eddy center are extracted. The ring or arc pattern in the middle of a normalized eddy appears when drifters are uninterruptedly entrained by eddies for more than 30 days. Moreover, the revolving channels of drifters in cyclonic eddies are relatively closer to the eddy center than those in anticyclonic eddies. These revolving channels suggest the principal mode of materials’ continuous motion processes that are inside eddies.

scholarly journals Unstable Frontal Waves along the Kuroshio Extension with Low-Potential Vorticity Intermediate Oyashio Water

2008 ◽  
Vol 38 (10) ◽  
pp. 2308-2321 ◽  
Author(s):  
Shinya Kouketsu ◽  
Ichiro Yasuda
Keyword(s):  
Potential Vorticity ◽  
Intermediate Layer ◽  
Kuroshio Extension ◽  
Phase Speed ◽  
Equation Model ◽  
Unstable Wave ◽  
Main Stream ◽  
Oyashio Water ◽  
Horizontal Variations ◽  
The Kuroshio

Abstract A linear stability analysis was conducted for a three-layer primitive equation model including viscosity with a basic state, which modeled the stratification and velocity fields with the vertical and horizontal variations across the Kuroshio Extension. An unstable wave with a wavelength of 220 km and a phase speed of 0.24 m s−1 propagating in the downstream direction was found to grow the fastest. Characteristics of this unstable baroclinic wave were similar to those of waves observed along the Kuroshio Extension. The growth rate of the fastest-growing waves became greater with an increase of the cross-stream difference of the potential vorticity (PV) in the intermediate layer. For a cross-frontal stratification structure without the PV gradient in the intermediate layer, which is similar to that in the Gulf Stream, the wavelength of the fastest-growing unstable wave changed to 390 km and the unstable wave had a much different structure. Thus, the unstable frontal waves observed along the Kuroshio Extension occur only for the cases when low-PV Oyashio water exists on the northern side of the main stream in the intermediate layer. The unstable frontal waves revealed in the present study greatly contribute to the formation of a clear salinity minimum in the Kuroshio Extension.

Sign in / Sign up

Export Citation Format

Share Document