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

Park, Jae‐Hyoung; Nam, SungHyun

doi:10.1029/2018jc014053

Cited by 7 publications

(13 citation statements)

References 54 publications

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“…Consequently, a thermal front is formed between these cold and warm anomalies. Furthermore, as reported in previous studies (e.g., [59][60][61]), the anticyclonic flows accompanied by northward coastal current reversal are generated by a negative wind stress curl. It may bring relatively warm and fresh water from the southern area into the downwelling region.…”

Section: Occurrence Of Mesoscale Features In the Nessupporting

confidence: 74%

Occurrence and Evolution of Mesoscale Thermodynamic Phenomena in the Northern Part of the East Sea (Japan Sea) Derived from Satellite Altimeter Data

Kim

Moon

2021

Remote Sensing

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Based on satellite measurements and oceanic reanalysis data, it has been possible to investigate the spatiotemporal variability of the mesoscale phenomena in the northern part of the East Sea (NES) where direct observations of currents and hydrographical conditions are scarce. For the first time, this study identifies the detailed spatiotemporal structure of the mesoscale features in the NES and the mechanism of its occurrence and evolution, which have important consequences on the distribution of the intermediate water masses in the East Sea. Here, we show that mesoscale thermodynamic phenomena in the northwestern region of the East Sea are characterized by a dipole structure associated with positive and negative sea surface height anomalies. These result in a strong thermal gradient between the seasonally non-persistent anomalies, which emerge and strengthen during late fall and early winter. In contrast to the previous finding of the relationship between winter monsoon winds and mesoscale features in the NES, we found that this relationship is crucial only to the emergence of the mesoscale phenomena. Consequently, we present a new perspective on the evolution mechanism of the mesoscale features in the NES. Of direct significance to the present study, thermohaline transport into the northwestern region of the East Sea regulates the strengthening and weakening of mesoscale features in the NES. Wind forcing may contribute to the emergence of the mesoscale features in the NES and then the intensification of the mesoscale activities is attributed to the intrusion of warm and fresh surface water advected from the southern part of the East Sea.

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Section: Occurrence Of Mesoscale Features In the Nessupporting

confidence: 74%

Occurrence and Evolution of Mesoscale Thermodynamic Phenomena in the Northern Part of the East Sea (Japan Sea) Derived from Satellite Altimeter Data

Kim

Moon

2021

Remote Sensing

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“…Standard error of the mean is employed in the present study for examining the significance of the mean value over the duration of available data, which is different from zero. The standard error of the mean, as in Park and Nam (2018), was calculated by,

\frac{σ_{std}}{\sqrt{{bold-italicN}_{e f f}}}

where

{bold-italicσ}_{bold-italicstd}

is the standard deviation (STD) of the variables and

{bold-italicN}_{e f f}

can be defined as,

{bold-italicN}_{e f f} = \frac{T h e n u m b e r o f d a t a}{d o u b l e d e - f o l d i n g t i m e l a g o f t h e a u t o c o r r e l a t i o n}

…”

Section: Methodsmentioning

confidence: 99%

Section: Estimating the Standard Error Of The Meanmentioning

confidence: 99%

A Newly Observed Deep Countercurrent in the Subtropical Northwest Pacific

et al. 2021

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The existence of a deep countercurrent in the subtropical northwest Pacific, named Subtropical Deep Countercurrent (STDCC), has been revealed by moored current‐meter data obtained from a buoy system (∼21.6°N, ∼132.8°E) during 4 years (2010–2014). The climatological average of Argo‐based absolute geostrophic velocities and ocean reanalyzes have further confirmed the spatial picture of the eastward‐flowing STDCC. STDCC is identified as a time‐mean feature in the latitudinal range of 19°–25°N with a meridional scale of 200–300 km that persistently appears from 125° to 180°E and slightly shifts to the north as it goes east. Vertically, STDCC is mostly found below 1,000 m with its core located between the depths of 1,250 and 2,000 m, which corresponds to the undercurrent's meridional pattern with increasing depth northward and a meridional space of 2°–4°. Nevertheless, STDCC is distinctive where it lies along ∼27.6 − σθ, which is deeper than the North Equatorial Undercurrent's density layer (∼27.0 − σθ). The mean velocity of STDCC at 2,000 m observed by mooring measurements was approximately 0.2 ± 0.15 cm s−1 with a maximum speed of approximately 5.59 cm s−1. The ocean reanalyzes also support the existence of STDCC with mean velocity of approximately 0.2–0.6 cm s−1 west of 145°E and can be as large as 1.6 cm s−1 at the eastern region. The results show that STDCC is closely related to the westward‐propagating eddies. Our finding emphasizes that the convergence of the cyclonic and anticyclonic eddies possibly generates time‐mean zonally elongated eastward flows forming STDCC feature.

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“…The seasonal standard deviations (m s −1 ) for the C of OPS are denoted with italic letters below the C of each segment. Park and Nam, 2018). This boundary condition is justified as the wind stresses at up-shelf grids around the origin was not large compared to those at down-shelf grids (e.g., W9, W18, and W32) so that inclusion of wind stresses at the up-shelf grids does not change the results significantly.…”

Section: Wind-forced Ctw Model and Its Applicationmentioning

confidence: 99%

“…Despite some previous studies explaining the subtidal coastal sea level fluctuations around the KP based on the classical CTW model under varying conditions of stratification and shelf topography (Lee and Chung, 1982;Lyu et al, 2002;Cho et al, 2014), the reasons for the significant difference between the observed (6.1-15.6 m s −1 ) and modeled (4.6-10.3 m s −1 ) propagation speeds are still poorly understood (Cho et al, 2014). In contrast, the subtidal sea level fluctuations off the east coast of the KP are also related to non-isostatic sea level responses to atmospheric pressure disturbances over a period of 2-20 days (Lyu et al, 2002;Nam et al, 2004;Jung et al, 2008), as well as a local upwelling/downwelling response to alongshore wind forcing beyond CTW dynamics (Park and Nam, 2018). Thus, our understanding of subtidal sea level fluctuations around the KP is far from complete; for example, how well the subtidal sea level fluctuations can be explained using the classic CTW and other dynamics beyond CTWs are poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Alongshore Propagation of Subtidal Sea Level Fluctuations Around the Korean Peninsula Over Varying Stratification and Shelf Topography

2022

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Understanding subtidal (a period band of 3–20 days) coastal sea level fluctuations is of increasing importance for the sustainable use of coastal areas under challenging conditions resulting from regional and global sea-level rise. The wind-forced coastal-trapped waves (CTW) theory often accounts for subtidal sea level fluctuations observed off global coasts with a considerable range of propagation speeds. Here, the propagation speeds of subtidal sea level fluctuations observed at seven coastal tide-gauge stations around the Korean Peninsula (KP) from 1997 to 2017 were compared with phase speeds modeled for 10 segments of realistic bottom topography around the KP and four seasons of density stratification using a wind-forced CTW model. Alongshore variations in the modeled phase speed (2.0–10.0 m s–1, increasing with the bottom depth, shelf width, and vertical density difference) were consistent with those of the observed propagation speed (4.7–18.9 m s–1), despite systematic underestimation by 50%, i.e., the mean speed of 6.0 vs. 11.8 m s–1. This underestimation is discussed considering subtidal sea level fluctuations of non-CTW origin that were not incorporated into the CTW model, such as (1) Barometric sea level response to atmospheric pressure disturbances, and (2) Upwelling/downwelling response to local alongshore wind stress. This study suggests that subtidal coastal sea level fluctuates around the KP within and beyond CTW dynamics.

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

Cited by 7 publications

References 54 publications

Occurrence and Evolution of Mesoscale Thermodynamic Phenomena in the Northern Part of the East Sea (Japan Sea) Derived from Satellite Altimeter Data

Occurrence and Evolution of Mesoscale Thermodynamic Phenomena in the Northern Part of the East Sea (Japan Sea) Derived from Satellite Altimeter Data

A Newly Observed Deep Countercurrent in the Subtropical Northwest Pacific

Alongshore Propagation of Subtidal Sea Level Fluctuations Around the Korean Peninsula Over Varying Stratification and Shelf Topography

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