Subtidal temperature variability in stratified shelf water off the mid-east coast of Korea

Cho, Changbong; Nam, SungHyun; Chang, Kyung‐Il

doi:10.1016/j.csr.2013.12.011

Cited by 8 publications

(19 citation statements)

References 19 publications

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“…The presumed cross-shore geostrophy is consistent with the observed thermal wind balance in the SWES region (inshore of the ESROB) [Cho et al, 2014]. The BCPG (high-density offshore) and CF terms are positive, and the RES x term is reasonably thought to represent primarily the cross-shore BTPG, hence, a geostrophic balance.…”

Section: 1002/2016gl069322supporting

confidence: 76%

Summertime coastal current reversal opposing offshore forcing and local wind near the middle east coast of Korea: Observation and dynamics

Park

Chang

Nam

2016

Geophysical Research Letters

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A 6 year long current measurement at a buoy station off the middle east coast of Korea reveals an equatorward reversal of coastal current in summer opposing poleward local wind stress and offshore boundary current. The current reversal extends about 40 km offshore from the coast and is concurrent with warming and freshening of water column. Estimates of the depth‐averaged alongshore momentum balance suggest a major balance between the alongshore pressure gradient and the lateral friction. Sources of the pressure gradient for the summertime current reversal are identified as the alongshore buoyancy gradient driven by the wind curl gradient and the prevalence of warmer and lower salinity water in the north. Alongshore pressure gradient and velocity induced by the wind curl gradient are quantified, which yields the observed seasonal current reversal.

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Section: 1002/2016gl069322supporting

confidence: 76%

Summertime coastal current reversal opposing offshore forcing and local wind near the middle east coast of Korea: Observation and dynamics

Park

Chang

Nam

2016

Geophysical Research Letters

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“…Interannual variations in the coefficients of the CTW model, F 1 , b 1 , c 1 , and a 1 because of the changes in stratification are not considered here, which might alter the results for v CTW . In the given range of N variation from spring to summer near the coast (~0.2 rad/s; Cho et al, ), which is an order of magnitude larger than the range in interannual N variation (~0.03 rad/s) estimated from the ESROB conductivity‐temperature‐depth data, b 1 , c 1 , and F 1 are rather insensitive to the N variation. Even if a 1 changes by a factor of 2 as is the case of the seasonal N variation, the bottom frictional length scale (6,250 km) is still sufficiently long compared to the distance between the remote forcing location and the ESROB (~1,000 km) such that the effect on a 1 with a change in N is negligible.…”

Section: Discussionmentioning

confidence: 95%

“…where c n , a n , and b n are the phase velocity, frictional decaying coefficient, and wind coupling coefficient of the n th mode CTWs, respectively. Here only the first mode CTWs playing a dominant role in the observed variance is of concern and the summer mean c 1 , a 1 , and b 1 applied in Cho et al () are used. The alongshore current driven by the CTWs is defined as ν CTW = − (1/ pf Δ x ) ϕ .…”

Section: Methodsmentioning

confidence: 99%

Causes of Interannual Variation of Summer Mean Alongshore Current Near the East Coast of Korea Derived From 16‐Year‐Long Observational Data

Park

Nam

2018

JGR Oceans

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Interannual variation in the summer surface current near the east coast of Korea was analyzed using long‐term (~16 years) time series measurements. Significant interannual variations in the summer alongshore current, which have a magnitude comparable to that of the climatological summer mean (equatorward) current, were observed. Positive anomalies (more poleward) occurred during 2001, 2009, 2010, and 2014; negative anomalies (more equatorward) occurred during 2002, 2006, and 2012. A linear combination of equatorward propagating coastal‐trapped waves, forced primarily by remote winds off the Russian coast, and an upwelling/downwelling response to local wind forcing, though contribution of the latter is not as significant as that of the former, successfully reproduced (46%) the observed anomalies in the alongshore current (correlation coefficient of 0.68). The influence of cross‐shore movement of the poleward flowing offshore current explains 35% of the total variance in the interannual anomalies of the alongshore current (correlation coefficient of 0.59), yielding less equatorward or slight poleward current near the coast in 2001 and 2009 with onshore movement of the offshore current. The combined effects of wind and offshore current explain ~72% (correlation coefficient of 0.85) of the anomalies in the alongshore current observed during summer near the east coast of Korea, providing significant implications for interannual current dynamics near the midlatitude western boundary.

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“…The c-SSLA is modulated by set-down and set-up of SSLA along the Korean coast by remote wind forcing over the western part of the EJS. The c-SSLA variations are produced mainly due to the southward propagation of Kelvin and shelf waves, or more generally costal trapped waves Cho et al 2014), which were generated by sea level set-down (set-up) along the east coast of Korea by southerly (northerly) wind stress over the EJS. Altered c-SSLA by long wave propagation intensifies or relaxes CM1 current in the strait.…”

Section: Discussionmentioning

confidence: 99%

“…Jacobs et al (2005) suggested that northerly (southerly) wind stress over the western part of the EJS sets up (down) a sea level along the east Korean coast, and these wind-forced sea level fluctuations propagate southward to the KS as Kelvin waves and change barotropic geostrophic transport through the KS. Coastal trapped waves propagating southward along the east coast of Korea were reported by Lee and Chung (1982), and recently Cho et al (2014) modelled the southward propagation of remote windforced coastal trapped waves off the east coast of Korea. These physical processes of sea level variations in the KS may be relevant in explaining the variations of c-SSLA and CM1.…”

Section: Wind Forcingmentioning

confidence: 95%

Vertical structure and variation of currents observed in autumn in the Korea Strait

Lee

Choi

2015

Ocean Sci. J.

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 To observe vertical structure and temporal variations of currents in the Tsushima Warm Current region of the Korea Strait, a moored buoy system was deployed in autumn 2009. The moored buoy system measured vertical profiles of current, temperature, and salinity for 24 days and a background hydrographic survey was performed. Along-strait northeastward currents were dominant in the upper layer (8-35 m). The mean current veers counterclockwise from 48 m to 74 m as much as 50°, and its speed is reduced with depth. There were distinct northward onshore currents near the bottom (65-80 m). It was demonstrated that thermal wind relation holds in the inclined pycnocline layer, which generates the counterclockwise veering current structure. Density gradient along the strait is a main factor producing the cross-strait onshore current component below the upper-layer and the cross-strait density gradient reduces the along-strait current component with depth. Previous studies have never focused on the effect of the along-strait density structure on current structure. The first Empirical Orthogonal Function mode (CM1) of current variability explains 70% of local current variations and its vertical structure is close to the mean current structure. The correlation analysis among variations of CM1 current, slope of sea level anomaly (SSLA) and local wind anomaly revealed that the variation of CM1 current is mainly related to the variation of SSLA across the strait (c-SSLA), which is known to be controlled by remote and local wind forcing. Similarity between vertical structures of mean and CM1 current suggests that thermal wind relation is the main dynamics maintaining the counterclockwise turning of CM1 current below the upper layer although the upperlayer CM1 current is controlled by c-SSLA through barotropic geostrophic relation. Time series of temperature and salinity indicate that the thermohaline front between Korean Coastal Water and Tsushima Warm Current Water meanders in time and migrates over the mooring station back and forth. The front meandering and migration also affect the local SSLA and CM1 current variations in autumn in the Korea Strait.

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Subtidal temperature variability in stratified shelf water off the mid-east coast of Korea

Cited by 8 publications

References 19 publications

Summertime coastal current reversal opposing offshore forcing and local wind near the middle east coast of Korea: Observation and dynamics

Summertime coastal current reversal opposing offshore forcing and local wind near the middle east coast of Korea: Observation and dynamics

Causes of Interannual Variation of Summer Mean Alongshore Current Near the East Coast of Korea Derived From 16‐Year‐Long Observational Data

Vertical structure and variation of currents observed in autumn in the Korea Strait

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