The Kuroshio Fronts and Cold Eddies off Northeastern Taiwan Observed by NOAA-AVHRR Imageries

Lin, Ching‐Fuh; Shyu, Chung-Zen; Shih, Wen-Hung

doi:10.3319/tao.1992.3.3.225(keep)

Cited by 33 publications

(17 citation statements)

References 2 publications

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“…These short‐term variations primarily occur in the summer and their durations range from 6 to 26 days, with an average of 15 ± 5 days. This duration matches those of previous studies by Lin et al () and Gopalakrishnan et al (). Moving trajectories can be classified into three types: quasi‐stationary, cross‐shelf northward, and along the Kuroshio Current northeastward.…”

Section: Discussionsupporting

confidence: 92%

Short‐Term Variations in the Surface Upwelling off Northeastern Taiwan Observed via Satellite Data

Yin

Huang

2019

JGR Oceans

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Short‐term biweekly variations in the surface upwelling off northeastern Taiwan are well documented. However, due to limitations in the spatiotemporal resolution and coverage of the observed data, the lifecycle and associated dynamics are poorly understood. In this study, a gradient‐based edge detection algorithm is proposed to detect the surface upwelling. The sea surface temperature data of geostationary satellite Himawari‐8 were used to explore a complete short‐term process as a case study. The evolution was analyzed in terms of an upwelling index measured via the temperature difference between upwelled and surrounding water and the area and shape of the surface upwelling. The process lasted approximately 17 days as the upwelling moved northeastward under the advection of the Kuroshio Current and included two stages: intensification and decay. The last 8 years (2010–2017) of multisatellite combined sea surface temperature data were examined to verify the results obtained in the case study. A statistical analysis shows that most of the short‐term processes occur in the summer with an average lifecycle of approximately 15 ± 5 days. The trajectories of the upwelling center can be grouped into three types: quasi‐stationary near the shelf break, moving northward across the shelf break, and moving northeastward along the shelf break. A preliminary discussion suggests that the observed variations may be caused by the collective effects of multiple dynamical mechanisms, such as fluctuations in the Kuroshio Current, surface wind curl, and typhoons. This study furthers our knowledge of the surface upwelling off northeastern Taiwan and provides constraints for numerical simulations.

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Section: Discussionsupporting

confidence: 92%

Short‐Term Variations in the Surface Upwelling off Northeastern Taiwan Observed via Satellite Data

Yin

Huang

2019

JGR Oceans

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“…A southwestward to southeastward countercurrent usually spans over the whole water column along the Mien-hua Canyon (MHC) (Hsueh et al, 1993;Tang and Yang, 1993) and is identi ed as a part of the eddy (Tang et al, 1998). An upwelling develops somewhere around the shelf break through the uplifting of intruded Kuroshio water (Fan 1980;Liu et al, 1992;Lin et al, 1992). The upwelling brings up sufficient nutrients (Liu et al, 1992) enhancing the chlorophyll a and primary productivity (Chen, 1992;Gong et al, 1997).…”

Section: ]mentioning

confidence: 99%

The effect of a cyclonic eddy on the distribution of lithogenic particles in the southern East China Sea

Hsu¹,

Lin²,

Jeng³

et al. 1998

Journal of Marine Research

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Off northeastern Taiwan, the collision between the Kuroshio Current (KC) and the East China Sea (ECS) shelf forms a branch current (Kuroshio Branch Current) on the shelf, and the counterclockwise de ection of the subsurface Kuroshio water annually generates a cyclonic eddy, about 70 km in diameter, over the shelf-slope in summer. In this study, the total suspended matter collected from varying water depths over the eddy duringAugust 1994 has been analyzed for Al, which is used as an indicator element to trace lithogenic particle transport. Simultaneously, the measurements of current eld, using the Shipboard Acoustic Doppler Current Pro ler, and hydrography have also been conducted on the same cruise during the seawater sampling. These offer an opportunity for direct examination of the relationships between circulation patterns and distributions of lithogenic particles to further establish a transport model for lithogenic particles. However, we must emphasize that this is a representative case for the export of terrigenous suspensions delivered from rivers, although the observation was made only in summer. The spatial distribution of particulateAl (PAl) in the upper water displays an ''V '' shape with high concentrations of PAl close to the Taiwan coast and around the eddy center. It suggests that Taiwan-derived riverborne particulates are the main source for the lithogenic particles in the upper water of the study area. Moreover, the PAl in the upper water is essentially constrained by the cyclonic eddy, and the entrainment and subsequent accumulation of lithogenic particles occur at the eddy center. The 6 µg/l contour of PAl in the upper water almost matches the western boundary of the main stream and branch of the KC across the ECS shelf-slope, and two concentration provinces of PAl can be identi ed from this contour: one to the west is larger and variable and the other to the east is smaller and uniform. This indicates that the main stream and branch of the KC may con ne terrigenousparticles to the inshore area where mixing of the lithogenic particle-richcoastal water and the clearer Kuroshio water occurs and may act as a barrier to the offshore transport of terrigenous particles to regions farther away from the coast, toward the north and east. In this study, a conceptual model for the transport of lithogenic particles in the water of the southern ECS is proposed according to the spatial distributions of PAl. This model suggests that the cyclonic eddy at the turning site of the KC may be the important conduit for the indirect transport of terrigenous particles from the ECS shelf and slope to the southern Okinawa Trough or the Paci c Ocean. This is also a valuable example of the role of the eddy system in regulating the distribution and transport of terrigenous particulates.

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“…Previous studies, including satellite observations, in-situ measurements, and numerical models suggested that the season of existence of the upwelling is still controversial. Lin et al [ 8 ] analyzed 118 SST images and found that the cold patch on the sea surface could be identified in 96 images. The cold patch induced by the upwelling can occupy over 3,700 km 2 area on the sea surface and reach a 6 °C difference from its coldest center to its surrounding waters.…”

Section: Introductionmentioning

confidence: 99%

An Algorithm for Cold Patch Detection in the Sea off Northeast Taiwan Using Multi-Sensor Data

Cheng

Zheng

et al. 2009

Sensors

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Multi-sensor data from different satellites are used to identify an upwelling area in the sea off northeast Taiwan. Sea surface temperature (SST) data derived from infrared and microwave, as well as sea surface height anomaly (SSHA) data derived from satellite altimeters are used for this study. An integration filtering algorithm based on SST data is developed for detecting the cold patch induced by the upwelling. The center of the cold patch is identified by the maximum negative deviation relative to the spatial mean of a SST image within the study area and its climatological mean of each pixel. The boundary of the cold patch is found by the largest SST gradient. The along track SSHA data derived from satellite altimeters are then used to verify the detected cold patch. Applying the detecting algorithm, spatial and temporal characteristics and variations of the cold patch are revealed. The cold patch has an average area of 1.92 × 104 km2. Its occurrence frequencies are high from June to October and reach a peak in July. The mean SST of the cold patch is 23.8 °C. In addition to the annual and the intraseasonal fluctuation with main peak centered at 60 days, the cold patch also has a variation period of about 4.7 years in the interannual timescale. This implies that the Kuroshio variations and long-term and large scale processes playing roles in modifying the cold patch occurrence frequency.

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The Kuroshio Fronts and Cold Eddies off Northeastern Taiwan Observed by NOAA-AVHRR Imageries

Cited by 33 publications

References 2 publications

Short‐Term Variations in the Surface Upwelling off Northeastern Taiwan Observed via Satellite Data

Short‐Term Variations in the Surface Upwelling off Northeastern Taiwan Observed via Satellite Data

The effect of a cyclonic eddy on the distribution of lithogenic particles in the southern East China Sea

An Algorithm for Cold Patch Detection in the Sea off Northeast Taiwan Using Multi-Sensor Data

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