scholarly journals Supplementary material to "Role of wind, mesoscale dynamics and coastal circulation in the interannual variability of South Vietnam Upwelling, South China Sea. Answers from a high resolution ocean model"

2022 ◽  
Author(s):  
Thai To Duy ◽  
Marine Herrmann ◽  
Claude Estournel ◽  
Patrick Marsaleix ◽  
Thomas Duhaut ◽  
...  
Keyword(s):  
High Resolution ◽  
South China Sea ◽  
Interannual Variability ◽  
South China ◽  
Ocean Model ◽  
Coastal Circulation ◽  
Mesoscale Dynamics ◽  
South Vietnam ◽  
Supplementary Material

Daily variability of upwellings ? The case study of South Vietnam upwelling (South China Sea)

2021 ◽  
Author(s):  
Thai Duy To ◽  
Marine Herrmann ◽  
Claude Estournel ◽  
Patrick Marsaleix ◽  
Thomas Duhaut ◽  
...  
Keyword(s):  
South China Sea ◽  
Interannual Variability ◽  
South China ◽  
Intrinsic Variability ◽  
The South ◽  
China Sea ◽  
Leading Role ◽  
South Vietnam ◽  
Daily Scale

<p>The South Vietnam upwelling (SVU) is one of the major processes involved in the South China Sea (SCS) ocean dynamics and planktonic ecosystem. Several numerical modelling studies examined its variability, revealing the leading role of wind and ENSO, but also, more recently, of ocean intrinsic variability (OIV) related to chaotic eddies. However, the spatial resolution of the models used in these studies did not allow to fully consider and understand the role of small scale dynamics. Our objective is therefore to implement a very high resolution model over the SCS in order to investigate the contribution of fine scale dynamics to the daily to interannual variability of the SVU.</p><p>We developed a configuration of the SYMPHONIE regional ocean model, using a curvilinear orthogonal grid over most of the SCS with a horizontal resolution increasing linearly from ~1.0 km along the Vietnamese coast to ~4.5 km offshore, and 50 layers. The surface forcing is prescribed using the 3-hourly output of the ECMWF, tidal forcing by FES2014, the initial and lateral ocean boundary conditions by the daily outputs of the global ocean 1/12° COPERNICUS analysis; monthly climatology and daily of freshwater river runoff are used for the 35 main rivers of the modeled domain.</p><p>We first evaluate the realism of the model by comparing a simulation performed over the period 2008-19 with in-situ measurements and satellite data. This multiannual simulation moreover confirms the leading role of wind on the daily to interannual variability of upwelling that develops in the coastal and offshore region. It also suggests, as already demonstrated by Da et al. (2019) at the interannual scale, that other processes are involved in this development. We thus explore the impact of ocean intrinsic variability, tides and rivers at the daily scale on the upwelling development by studying in details the intense upwelling that develops during summer 2018. For that, we perform several sensitivity experiments including ensemble simulations with perturbated initial conditions. We will present a synthesis of the results that reveal the strong impact of ocean background mesoscale circulation on the upwelling intensity at the daily scale, and its evolution during the summer.</p>

scholarly journals Role of wind, mesoscale dynamics and coastal circulation in the interannual variability of South Vietnam Upwelling, South China Sea. Answers from a high resolution ocean model

2022 ◽  
Author(s):  
Thai To Duy ◽  
Marine Herrmann ◽  
Claude Estournel ◽  
Patrick Marsaleix ◽  
Thomas Duhaut ◽  
...  
Keyword(s):  
South China Sea ◽  
Interannual Variability ◽  
South China ◽  
Coastal Region ◽  
Mekong Delta ◽  
The South ◽  
Offshore Area ◽  
China Sea ◽  
South Vietnam

Abstract. The South Vietnam Upwelling (SVU) develops in the South China Sea off the Vietnamese coast under the influence of southwest monsoon winds. A very high resolution configuration (1 km at the coast) of the SYMPHONIE model was developed over the western coastal region of the South China Sea. A simulation was performed over the period 2009–2018 to study the functioning, variability and influence of oceanic circulation and hydrology in the coastal region, in particular of the SVU. The realism of the simulation in terms of representation of ocean dynamics and water masses, from daily to interannual and coastal to regional scales, is assessed here in detail by comparison with available satellite data and 4 sets of in-situ observations. The interannual variability of the SVU is examined for its 4 main development areas: the southern (SCU) and northern (NCU) coasts, the offshore area (OFU), and the Sunda Shelf area off the Mekong Delta (MKU). For the SCU and OFU, our results confirm the driving role of the summer mean wind and the summer circulation over the offshore area in the interannual variability of the upwelling intensity. They moreover reveal the impact of the spatial and temporal organization of mesoscale ocean structures and high frequency atmospheric forcing. For the NCU, the upwelling interannual variability does not seem to be related to regional scale forcing and dynamics, but is mainly determined by coastal mesoscale structures and circulation: similar summer wind conditions can be associated with very contrasting NCU intensities, and vice versa, depending on the circulation in the NCU area. Finally, our study reveals that upwelling also develops off the Mekong Delta, with an interannual variability mostly determined by the summer wind and the wind-driven circulation over the SVU region.

scholarly journals Opposite Variability of Indonesian Throughflow and South China Sea Throughflow in the Sulawesi Sea

2016 ◽  
Vol 46 (10) ◽  
pp. 3165-3180 ◽  
Author(s):  
Jun Wei ◽  
M. T. Li ◽  
P. Malanotte-Rizzoli ◽  
A. L. Gordon ◽  
D. X. Wang
Keyword(s):  
South China Sea ◽  
Interannual Variability ◽  
South China ◽  
Pressure Head ◽  
Ocean Model ◽  
North Equatorial Current ◽  
Indonesian Throughflow ◽  
China Sea ◽  
South China Sea Throughflow ◽  
Budget Analysis

AbstractBased on a high-resolution (0.1° × 0.1°) regional ocean model covering the entire northern Pacific, this study investigated the seasonal and interannual variability of the Indonesian Throughflow (ITF) and the South China Sea Throughflow (SCSTF) as well as their interactions in the Sulawesi Sea. The model efficiency in simulating the general circulations of the western Pacific boundary currents and the ITF/SCSTF through the major Indonesian seas/straits was first validated against the International Nusantara Stratification and Transport (INSTANT) data, the OFES reanalysis, and results from previous studies. The model simulations of 2004–12 were then analyzed, corresponding to the period of the INSTANT program. The results showed that, derived from the North Equatorial Current (NEC)–Mindanao Current (MC)–Kuroshio variability, the Luzon–Mindoro–Sibutu flow and the Mindanao–Sulawesi flow demonstrate opposite variability before flowing into the Sulawesi Sea. Although the total transport of the Mindanao–Sulawesi flow is much larger than that of the Luzon–Mindoro–Sibutu flow, their variability amplitudes are comparable but out of phase and therefore counteract each other in the Sulawesi Sea. Budget analysis of the two major inflows revealed that the Luzon–Mindoro–Sibutu flow is enhanced southward during winter months and El Niño years, when more Kuroshio water intrudes into the SCS. This flow brings more buoyant SCS water into the western Sulawesi Sea through the Sibutu Strait, building up a west-to-east pressure head anomaly against the Mindanao–Sulawesi inflow and therefore resulting in a reduced outflow into the Makassar Strait. The situation is reversed in the summer months and La Niña years, and this process is shown to be more crucially important to modulate the Makassar ITF’s interannual variability than the Luzon–Karimata flow that is primarily driven by seasonal monsoons.

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