scholarly journals Coastal Upwelling Limitation by Onshore Geostrophic Flow in the Gulf of Guinea Around the Niger River Plume

2021 ◽  
Vol 7 ◽  
Author(s):  
Gaël Alory ◽  
Casimir Yélognissè Da-Allada ◽  
Sandrine Djakouré ◽  
Isabelle Dadou ◽  
Julien Jouanno ◽  
...  
Keyword(s):  
Coastal Upwelling ◽  
Ocean Model ◽  
River Plume ◽  
Gulf Of Guinea ◽  
Sea Level Changes ◽  
Current Increase ◽  
Geostrophic Flow ◽  
Regional Ocean Model ◽  
Niger River ◽  
Induced Changes

Wind-driven coastal upwelling can be compensated by onshore geostrophic flow, and river plumes are associated with such flow. We investigate possible limitation of the northeast Gulf of Guinea upwelling by the Niger River plume, using regional ocean model simulations with or without river and dynamical upwelling indices. Here, the upwelling is weakened by 50% due to an onshore geostrophic flow equally controlled by alongshore thermosteric and halosteric sea-level changes. The river contributes to only 20% of this flow, as its plume is shallow while upwelling affects coastal temperature and salinity over a larger depth. Moreover, the river-induced mixed-layer thinning compensates the current increase, with no net effect on upwelling. The geostrophic compensation is due to an abrupt change in coastline orientation that creates the upwelling cross-shore front. The river nonetheless warms the upwelling tongue by 1°C, probably due to induced changes in horizontal advection and/or stratification.

scholarly journals Mesoscale ocean fronts enhance carbon export due to gravitational sinking and subduction

2017 ◽  
Vol 114 (6) ◽  
pp. 1252-1257 ◽  
Author(s):  
Michael R. Stukel ◽  
Lihini I. Aluwihare ◽  
Katherine A. Barbeau ◽  
Alexander M. Chekalyuk ◽  
Ralf Goericke ◽  
...  
Keyword(s):  
Coastal Upwelling ◽  
Sediment Traps ◽  
Ocean Model ◽  
Model Fit ◽  
New Production ◽  
Carbon Export ◽  
Ocean Fronts ◽  
Regional Ocean Model ◽  
Particle Export

Enhanced vertical carbon transport (gravitational sinking and subduction) at mesoscale ocean fronts may explain the demonstrated imbalance of new production and sinking particle export in coastal upwelling ecosystems. Based on flux assessments from 238U:234Th disequilibrium and sediment traps, we found 2 to 3 times higher rates of gravitational particle export near a deep-water front (305 mg C⋅m−2⋅d−1) compared with adjacent water or to mean (nonfrontal) regional conditions. Elevated particle flux at the front was mechanistically linked to Fe-stressed diatoms and high mesozooplankton fecal pellet production. Using a data assimilative regional ocean model fit to measured conditions, we estimate that an additional ∼225 mg C⋅m−2⋅d−1 was exported as subduction of particle-rich water at the front, highlighting a transport mechanism that is not captured by sediment traps and is poorly quantified by most models and in situ measurements. Mesoscale fronts may be responsible for over a quarter of total organic carbon sequestration in the California Current and other coastal upwelling ecosystems.

scholarly journals ICONGETM v1.0 – Flexible two-way coupling via exchange grids between the unstructured-grid atmospheric model ICON and the structured-grid coastal ocean model GETM

2020 ◽  
Author(s):  
Tobias Peter Bauer ◽  
Knut Klingbeil ◽  
Peter Holtermann ◽  
Bernd Heinold ◽  
Hagen Radtke ◽  
...  
Keyword(s):  
Data Exchange ◽  
Coastal Upwelling ◽  
Atmospheric Model ◽  
Ocean Model ◽  
Coupled Models ◽  
Structured Grid ◽  
Process Understanding ◽  
Regional Ocean Model ◽  
Coastal Ocean Model

Abstract. Coupled atmosphere-ocean models are developed for process understanding at the air-sea interface. Over the last 20 years, there have been studies involving simulations in the range of sub-annual simulations to climate scenarios. The development of coupled models highly depends on the kind and quality of the required data exchange between the model interfaces. This work achieved the development of a two-way coupled atmosphere-ocean model ICONGETM with flexible data exchange via exchange grids provided by the widely used ESMF regridding package. The regridding of flux data between the unstructured atmosphere model ICON and the structured regional ocean model GETM is conducted via these exchange grids. The newly developed model ICONGETM has been demonstrated for a coastal upwelling scenario in the Central Baltic Sea.

scholarly journals The effect of coastal upwelling on the sea-breeze circulation at Cabo Frio, Brazil: a numerical experiment

1998 ◽  
Vol 16 (7) ◽  
pp. 866-871 ◽  
Author(s):  
S. H. Franchito ◽  
V. B. Rao ◽  
J. L. Stech ◽  
J. A. Lorenzzetti
Keyword(s):  
Coastal Upwelling ◽  
Surface Wind ◽  
Three Dimensional ◽  
Sea Breeze ◽  
Atmospheric Model ◽  
Ocean Model ◽  
Breeze Circulation ◽  
Mesoscale Meteorology ◽  
Forcing Function ◽  
Cabo Frio

Abstract. The effect of coastal upwelling on sea-breeze circulation in Cabo Frio (Brazil) and the feedback of sea-breeze on the upwelling signal in this region are investigated. In order to study the effect of coastal upwelling on sea-breeze a non-linear, three-dimensional, primitive equation atmospheric model is employed. The model considers only dry air and employs boundary layer formulation. The surface temperature is determined by a forcing function applied to the Earth's surface. In order to investigate the seasonal variations of the circulation, numerical experiments considering three-month means are conducted: January-February-March (JFM), April-May-June (AMJ), July-August-September (JAS) and October-November-December (OND). The model results show that the sea-breeze is most intense near the coast at all the seasons. The sea-breeze is stronger in OND and JFM, when the upwelling occurs, and weaker in AMJ and JAS, when there is no upwelling. Numerical simulations also show that when the upwelling occurs the sea-breeze develops and attains maximum intensity earlier than when it does not occur. Observations show a similar behavior. In order to verify the effect of the sea-breeze surface wind on the upwelling, a two-layer finite element ocean model is also implemented. The results of simulations using this model, forced by the wind generated in the sea-breeze model, show that the sea-breeze effectively enhances the upwelling signal.Key words. Meteorology and atmospheric dynamics (mesoscale meteorology; ocean-atmosphere interactions) · Oceanography (numerical modeling)

scholarly journals The Benguela Upwelling System: Quantifying the Sensitivity to Resolution and Coastal Wind Representation in a Global Climate Model*

2015 ◽  
Vol 28 (23) ◽  
pp. 9409-9432 ◽  
Author(s):  
R. Justin Small ◽  
Enrique Curchitser ◽  
Katherine Hedstrom ◽  
Brian Kauffman ◽  
William G. Large
Keyword(s):  
Wind Stress ◽  
Climate Model ◽  
Coastal Upwelling ◽  
Ocean Model ◽  
Wind Stress Curl ◽  
Upwelling System ◽  
Wind Structure ◽  
Eastern Boundary ◽  
Benguela Upwelling ◽  
Atmosphere Model

Abstract Of all the major coastal upwelling systems in the world’s oceans, the Benguela, located off southwest Africa, is the one that climate models find hardest to simulate well. This paper investigates the sensitivity of upwelling processes, and of sea surface temperature (SST), in this region to resolution of the climate model and to the offshore wind structure. The Community Climate System Model (version 4) is used here, together with the Regional Ocean Modeling System. The main result is that a realistic wind stress curl at the eastern boundary, and a high-resolution ocean model, are required to well simulate the Benguela upwelling system. When the wind stress curl is too broad (as with a 1° atmosphere model or coarser), a Sverdrup balance prevails at the eastern boundary, implying southward ocean transport extending as far as 30°S and warm advection. Higher atmosphere resolution, up to 0.5°, does bring the atmospheric jet closer to the coast, but there can be too strong a wind stress curl. The most realistic representation of the upwelling system is found by adjusting the 0.5° atmosphere model wind structure near the coast toward observations, while using an eddy-resolving ocean model. A similar adjustment applied to a 1° ocean model did not show such improvement. Finally, the remote equatorial Atlantic response to restoring SST in a broad region offshore of Benguela is substantial; however, there is not a large response to correcting SST in the narrow coastal upwelling zone alone.

Implementation and Validating of the Regional Ocean Model System (ROMS) for the Sunda Strait connecting the Java Sea to the Indian Ocean

2021 ◽  
Author(s):  
Subekti Mujiasih ◽  
Jean-Marie Beckers ◽  
Alexander Barth
Keyword(s):  
Time Series ◽  
Indian Ocean ◽  
Vertical Profile ◽  
Ocean Model ◽  
Model System ◽  
Satellite Sst ◽  
Regional Ocean Model System ◽  
Regional Ocean Model ◽  
The Indian Ocean ◽  
Java Sea

<p>Regional Ocean Model System (ROMS) has been simulated for the Sunda Strait, the Java Sea, and the Indian Ocean. The simulation was undertaken for thirteen months of data period (August 2013 – August 2014). However, we only used four months period for validation, namely September – December 2013. The input data involved the HYbrid Coordinate Ocean Model (HYCOM) ocean model output by considering atmospheric forcing from the European Centre for Medium-Range Weather Forecasts (ECMWF), without and with tides forcing from TPXO and rivers. The output included vertical profile temperature and salinity, sea surface temperature (SST), seas surface height (SSH), zonal (u), and meridional (v) velocity. We compared the model SST to satellite SST in time series, SSH to tides gauges data in time series, the model u and v component velocity to High Frequency (HF) radial velocity. The vertical profile temperature and salinity were compared to Argo float data and XBT. Besides, we validated the amplitude and phase of the ROMS seas surface height to amplitude and phase of the tides-gauges, including four constituents (M2, S2, K1, O1).</p>

Application of HY-2 Satellite SST Data in 4D Variational Assimilation Ocean Forecast Model

2017 ◽  
Vol 8 (2) ◽  
pp. 15-26
Author(s):  
Zhenchang Zhang ◽  
Libin Gao ◽  
Minquan Guo ◽  
Riqing Chen
Keyword(s):  
Time Window ◽  
Forecast Model ◽  
Ocean Model ◽  
Satellite Sst ◽  
Regional Ocean Model System ◽  
Model Research ◽  
Numerical Ocean Model ◽  
Regional Ocean Model ◽  
Taiwan Straits ◽  
Marine Environmental

The 4D variational (4DVAR) assimilation numerical ocean model research is proposed. This model for Taiwan Straits (TWS) is based on Regional Ocean Model System (ROMS). The background of the 4DVAR method is introduced and the development process of assimilation system is presented. In the present research, the model assimilated with Sea Surface Temperature (SST) data of HY-2 satellite (Qi, 2012; Xu, 2013) which is the first marine environmental monitoring satellite of China. In this paper, the model processes from Feb. 1 to Feb. 7, 2014 with one-day assimilation time window and root mean square error (RMSE) reduces averagely by 14.7%.

Sign in / Sign up

Export Citation Format

Share Document