Observation of Tropical Cyclone‐Induced Shallow Water Currents in Taiwan Strait

Shen, Junqiang; Qiu, Yun; Zhang, Shanwu; Kuang, Fangfang

doi:10.1002/2017jc012737

Cited by 23 publications

(33 citation statements)

References 51 publications

(64 reference statements)

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“…For a slow-moving and super strong typhoon, the maximum mixed layer current velocity is roughly twice that of a fast-moving and weak typhoon. Typhoon-induced near-inertial motions are dominant during the relaxation stage, and barotropic subinertial waves and baroclinic near-inertial oscillations were both observed at this time, indicating a subinertial wave period of 2.8-4.1 days [25]. Near-inertial oscillations decayed more rapidly in shallow water than in the deep ocean, which emphasized the importance of frictional effects for characterizing responses to typhoon forcing in the shallow ocean [26].…”

Section: Introductionmentioning

confidence: 89%

Upper Ocean Response to Typhoon Kalmaegi and Sarika in the South China Sea from Multiple-Satellite Observations and Numerical Simulations

et al. 2018

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We investigated ocean surface and subsurface physical responses to Typhoons Kalmaegi and Sarika in the South China Sea, utilizing synergistic multiple-satellite observations, in situ measurements, and numerical simulations. We found significant typhoon-induced sea surface cooling using satellite sea surface temperature (SST) observations and numerical model simulations. This cooling was mainly caused by vertical mixing and upwelling. The maximum amplitudes were 6 • C and 4.2 • C for Typhoons Kalmaegi and Sarika, respectively. For Typhoon Sarika, Argo temperature profile measurements showed that temperature response beneath the surface showed a three-layer vertical structure (decreasing-increasing-decreasing). Satellite salinity observations showed that the maximum increase of sea surface salinity (SSS) was 2.2 psu on the right side of Typhoon Sarika's track, and the maximum decrease of SSS was 1.4 psu on the left. This SSS seesaw response phenomenon is related to the asymmetrical rainfall on both sides of the typhoon track. Acoustic Doppler Current Profilers measurements and numerical simulations both showed that subsurface current velocities rapidly increased as the typhoon passed, with peak increases of up to 1.19 m/s and 1.49 m/s. Typhoon-generated SST cooling and current velocity increases both exhibited a rightward bias associated with a coupling between typhoon wind-stress and mixed layer velocity.

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Section: Introductionmentioning

confidence: 89%

Upper Ocean Response to Typhoon Kalmaegi and Sarika in the South China Sea from Multiple-Satellite Observations and Numerical Simulations

et al. 2018

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“…It seems that the NICs were from the residual near‐inertial energy generated by TC Prapiroon, which moved northwestward toward the mainland from the NSCS during 2–3 August (Figure 1). TC Prapiroon significantly impacted these moorings due to its large radius and the fact that all the moorings were located on its right side (Shen et al, 2017). Interestingly, although the surface wind stress in the case of Bopha was generally weak and seemed to assume similar amplitudes at different moorings, the amplitudes of the NICs appeared to be quite different.…”

Section: Resultsmentioning

confidence: 99%

Observed Internal Tides and Near‐Inertial Waves in the Northern South China Sea: Intensified f‐Band Energy Induced by Parametric Subharmonic Instability

et al. 2020

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The variations in the internal tide (IT) and near-inertial waves (NIWs) that occurred in the summer of 2006 over the continental shelf of the northern South China Sea were observed using three bottom-mounted moorings equipped with acoustic Doppler current profilers. Due to the strong nonlinear interaction, large portions (~40-60%) of the semidiurnal IT energy at the continental shelf were found to be incoherent; this proportion gradually increased from the shelf break to the offshore region. More importantly, our observations showed that parametric subharmonic instability (PSI) can enhance the f-band energy in the shallow water (~100 m) on the continental shelf. Using plane-wave fitting and the bicoherence spectrum, we confirmed that the intensified NIWs and the observed D2-f waves are nonlinear coupled waves derived from the semidiurnal internal tidal PSI. These two subharmonic waves were observed in the near field of a strong semidiurnal IT generation site at the shelf break. By tracking the M2-ray path, we verified that the PSI occurred in the pycnocline in the path of the reflected wave beam that was characterized by strong nonlinear instabilities and it could be modulated by mesoscale eddies in this shallow shelf water. Plain Language Summary Internal tides and near-inertial waves, as two types of internal waves, have often been observed in the northern South China Sea (NSCS). Known as the most important characteristic so far in this region, the former vary seasonally and spatially while the latter are mainly concentrated in the upper layers supplied by wind forcing. The internal waves on the continental shelf of the NSCS in summertime were monitored synchronously using bottom moorings. We found that the semidiurnal internal tides exhibited both coherent and incoherent features and that the near-inertial waves remarkably intensified in the pycnocline, which was not directly induced by wind. Previous studies have revealed that parametric subharmonic instability (PSI) can efficiently transfer energy from semidiurnal internal tides to near-inertial waves. In this work, we found that semidiurnal internal tidal PSI does occur in the near field of a strong semidiurnal internal tide generation site at the shelf break when the water is well stratified. However, due to the passage of mesoscale eddies, the stratified waters can change, resulting in PSI interruption. Overall, this study aims to improve our understanding of the internal tides and near-inertial waves in the NSCS and the energy transfer mechanism of PSI.

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“…As the storm approached (26-28 July), the surface heat flux gradually declined to zero, allowing advection to cool the water below 30 m depth (Figure 11b). During the direct forcing period (29)(30), surface heat flux reversed to a negative state, indicative of heat loss that reduced its overall magnitude. During the departure period (30 July-1 August), surface heat loss was further increased, reaching a maximum value on 31 July (~200 W m −2 ), then gradually reduced to zero (Figure 11a).…”

Section: Diagnostic Analysis For Heat Budgetmentioning

confidence: 99%

“…Figure 2 in [25]), yet despite their impact on the environment of the TWS, studies are still limited. Research within the last decade has focused on analysis of storm surges [26,27], the importance of tide-surge or wave-tide-surge interactions in predicting the storm tide [25], or consideration of volume transport [20], sediment transport [28]), and currents [29,30]. In this study, a fully coupled ocean-atmosphere-wave model system [31] with a high horizontal resolution (~1 km) is employed to investigate the response of the TWS to Typhoon Nesat (2017).…”

Section: Introductionmentioning

confidence: 99%

Response of Coastal Water in the Taiwan Strait to Typhoon Nesat of 2017

Yang

Tian

et al. 2019

Water

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The oceanic response of the Taiwan Strait (TWS) to Typhoon Nesat (2017) was investigated using a fully coupled atmosphere-ocean-wave model (COAWST) verified by observations. Ocean currents in the TWS changed drastically in response to significant wind variation during the typhoon. The response of ocean currents was characterised by a flow pattern generally consistent with the Ekman boundary layer theory, with north-eastward volume transport being significantly modified by the storm. Model results also reveal that the western TWS experienced the maximum generated storm surge, whereas the east side experienced only moderate storm surge. Heat budget analysis indicated that surface heat flux, vertical diffusion, and total advection all contributed to changes in water temperature in the upper 30 m with advection primarily affecting lower depths during the storm. Momentum balance analysis shows that along-shore volume acceleration was largely determined by a combined effect of surface wind stress and bottom stress. Cross-shore directional terms of pressure gradient and Coriolis acceleration were dominant throughout the model run, indicating that the effect of the storm on geostrophic balance was small. This work provides a detailed analysis of TWS water response to typhoon passage across the strait, which will aid in regional disaster management.

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Observation of Tropical Cyclone‐Induced Shallow Water Currents in Taiwan Strait

Cited by 23 publications

References 51 publications

Upper Ocean Response to Typhoon Kalmaegi and Sarika in the South China Sea from Multiple-Satellite Observations and Numerical Simulations

Upper Ocean Response to Typhoon Kalmaegi and Sarika in the South China Sea from Multiple-Satellite Observations and Numerical Simulations

Observed Internal Tides and Near‐Inertial Waves in the Northern South China Sea: Intensified f‐Band Energy Induced by Parametric Subharmonic Instability

Response of Coastal Water in the Taiwan Strait to Typhoon Nesat of 2017

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