scholarly journals Development of a 2-way coupled ocean-wave model: assessment on a global NEMO(v3.6)-WW3(v6.02) coupled configuration

2019 ◽  
Author(s):  
Xavier Couvelard ◽  
Florian Lemarié ◽  
Guillaume Samson ◽  
Jean-Luc Redelsperger ◽  
Fabrice Ardhuin ◽  
...  
Keyword(s):  
General Circulation ◽  
Three Dimensional ◽  
Circulation Model ◽  
Wave Model ◽  
Ocean General Circulation Model ◽  
Model Assessment ◽  
Closure Scheme ◽  
Ocean Wave Model ◽  
Tke Closure ◽  
The Impact

Abstract. This paper describes the implementation of a coupling between a three-dimensional ocean general circulation model (NEMO) and a wave model (WW3) to represent the interactions of the upper oceanic flow dynamics with surface waves. The focus is on the impact of such coupling on upper-ocean properties (temperature and currents) and mixed-layer depths (MLD) at global eddying scales. A generic coupling interface has been developed and the NEMO governing equations and boundary conditions have been adapted to include wave-induced terms following the approach of McWilliams et al. (2004) and Ardhuin et al. (2008). In particular, the contributions of Stokes-Coriolis, Vortex and surface pressure forces have been implemented on top of the necessary modifications of the tracer/continuity equation and turbulent closure scheme (a 1-equation TKE closure here). To assess the new developments, we perform a set of sensitivity experiments with a global oceanic configuration at 1/4° resolution coupled with a wave model configured at 1/2° resolution. Numerical simulations show a global increase of wind-stress due to the interaction with waves (via the Charnock coefficient) particularly at high latitudes. The modifications brought to the TKE closure scheme and the inclusion of a parameterization for Langmuir turbulence lead to a significant increase of the mixing thus helping to deepen the MLD. This deepening is mainly located in the Southern Hemisphere and results in reduced sea-surface currents and temperatures.

scholarly journals Development of a two-way-coupled ocean–wave model: assessment on a global NEMO(v3.6)–WW3(v6.02) coupled configuration

2020 ◽  
Vol 13 (7) ◽  
pp. 3067-3090
Author(s):  
Xavier Couvelard ◽  
Florian Lemarié ◽  
Guillaume Samson ◽  
Jean-Luc Redelsperger ◽  
Fabrice Ardhuin ◽  
...  
Keyword(s):  
General Circulation ◽  
Mixed Layer Depth ◽  
Circulation Model ◽  
Wave Model ◽  
Ocean General Circulation Model ◽  
Surface Currents ◽  
Model Assessment ◽  
Closure Scheme ◽  
Tke Closure ◽  
The Impact

Abstract. This paper describes the implementation of a coupling between a three-dimensional ocean general circulation model (NEMO) and a wave model (WW3) to represent the interactions of upper-oceanic flow dynamics with surface waves. The focus is on the impact of such coupling on upper-ocean properties (temperature and currents) and mixed layer depth (MLD) at global eddying scales. A generic coupling interface has been developed, and the NEMO governing equations and boundary conditions have been adapted to include wave-induced terms following the approach of McWilliams et al. (2004) and Ardhuin et al. (2008). In particular, the contributions of Stokes–Coriolis, vortex, and surface pressure forces have been implemented on top of the necessary modifications of the tracer–continuity equation and turbulent closure scheme (a one-equation turbulent kinetic energy – TKE – closure here). To assess the new developments, we perform a set of sensitivity experiments with a global oceanic configuration at 1/4∘ resolution coupled with a wave model configured at 1/2∘ resolution. Numerical simulations show a global increase in wind stress due to the interaction with waves (via the Charnock coefficient), particularly at high latitudes, resulting in increased surface currents. The modifications brought to the TKE closure scheme and the inclusion of a parameterization for Langmuir turbulence lead to a significant increase in the mixing, thus helping to deepen the MLD. This deepening is mainly located in the Southern Hemisphere and results in reduced sea surface currents and temperatures.

scholarly journals The Rossby radius in the Arctic Ocean

Ocean Science ◽  
2014 ◽  
Vol 10 (6) ◽  
pp. 967-975 ◽  
Author(s):  
A. J. G. Nurser ◽  
S. Bacon
Keyword(s):  
Arctic Ocean ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
High Arctic ◽  
The Arctic ◽  
Hudson Bay ◽  
Ocean Eddies ◽  
Shelf Seas ◽  
The Impact

Abstract. The first (and second) baroclinic deformation (or Rossby) radii are presented north of ~60° N, focusing on deep basins and shelf seas in the high Arctic Ocean, the Nordic seas, Baffin Bay, Hudson Bay and the Canadian Arctic Archipelago, derived from climatological ocean data. In the high Arctic Ocean, the first Rossby radius increases from ~5 km in the Nansen Basin to ~15 km in the central Canadian Basin. In the shelf seas and elsewhere, values are low (1–7 km), reflecting weak density stratification, shallow water, or both. Seasonality strongly impacts the Rossby radius only in shallow seas, where winter homogenization of the water column can reduce it to below 1 km. Greater detail is seen in the output from an ice–ocean general circulation model, of higher resolution than the climatology. To assess the impact of secular variability, 10 years (2003–2012) of hydrographic stations along 150° W in the Beaufort Gyre are also analysed. The first-mode Rossby radius increases over this period by ~20%. Finally, we review the observed scales of Arctic Ocean eddies.

scholarly journals Modeling the present and future impact of aviation on climate: an AOGCM approach with online coupled chemistry

2013 ◽  
Vol 13 (19) ◽  
pp. 10027-10048 ◽  
Author(s):  
P. Huszar ◽  
H. Teyssèdre ◽  
M. Michou ◽  
A. Voldoire ◽  
D. J. L. Olivié ◽  
...  
Keyword(s):  
Co2 Emissions ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Climate Impacts ◽  
Ozone Production ◽  
The Arctic ◽  
Near Surface ◽  
Aviation Emissions ◽  
The Impact

Abstract. Our work is among the first that use an atmosphere-ocean general circulation model (AOGCM) with online chemistry to evaluate the impact of future aviation emissions on temperature. Other particularities of our study include non-scaling to the aviation emissions, and the analysis of models' transient response using ensemble simulations. The model we use is the Météo-France CNRM-CM5.1 earth system model extended with the REPROBUS chemistry scheme. The time horizon of our interest is 1940–2100, assuming the A1B SRES scenario. We investigate the present and future impact of aviation emissions of CO2, NOx and H2O on climate, taking into account changes in greenhouse gases, contrails and contrail-induced cirrus (CIC). As in many transport-related impact studies, we distinguish between the climate impacts of CO2 emissions and those of non-CO2 emissions. Aviation-produced aerosol is not considered in the study. Our modeling system simulated a notable sea-ice bias in the Arctic, and therefore results concerning the surface should be viewed with caution. The global averaged near-surface CO2 impact reaches around 0.1 K by the end of the 21st century, while the non-CO2 impact reaches 0.2 K in the second half of the century. The NOx emissions impact is almost negligible in our simulations, as our aviation-induced ozone production is small. As a consequence, the non-CO2 signal is very similar to the CIC signal. The seasonal analysis shows that the strongest warming due to aviation is modeled for the late summer and early autumn. In the stratosphere, a significant cooling is attributed to aviation CO2 emissions (−0.25 K by 2100). A −0.3 K temperature decrease is modeled when considering all the aviation emissions, but no significant signal appears from the CIC or NOx forcings in the stratosphere.

scholarly journals The Three-Dimensional Steady Circulation in a Homogenous Ocean Induced by a Stationary Hurricane

2010 ◽  
Vol 40 (7) ◽  
pp. 1441-1457 ◽  
Author(s):  
Zhu Min Lu ◽  
Rui Xin Huang
Keyword(s):  
Analytical Solution ◽  
General Circulation ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Coriolis Parameter ◽  
Middle Latitudes ◽  
Oceanic Response ◽  
Stratified Ocean

Abstract Based on the classical Ekman layer theory, a simple analytical solution of the steady flow induced by a stationary hurricane in a homogenous ocean is discussed. The model consists of flow converging in an inward spiral in the deeper layer and diverging in the upper layer. The simple analytical model indicates that both the upwelling flux and the horizontal transport increase linearly with increasing radius of maximum winds. Furthermore, they both have a parabolic relationship with the maximum wind speed. The Coriolis parameter also affects the upwelling flux: the response to a hurricane is stronger at low latitudes than that at middle latitudes. Numerical solutions based on a regional version of an ocean general circulation model are similar to the primary results obtained through the analytical solution. Thus, the simplifications made in formulating the analytical solution are reasonable. Although the analytical solution in this paper is sought for a rather idealized ocean, it can help to make results from the more complicated numerical model understandable. These conceptual models provide a theoretical limit structure of the oceanic response to a moving hurricane over a stratified ocean.

scholarly journals Ocean-sea-ice coupling in a global ocean general circulation model

1997 ◽  
Vol 25 ◽  
pp. 116-120 ◽  
Author(s):  
S. Legutke ◽  
E. Maier-Reimkr ◽  
A. Stössel ◽  
A. Hellbach
Keyword(s):  
Sea Ice ◽  
General Circulation Model ◽  
Ocean Circulation ◽  
General Circulation ◽  
Circulation Model ◽  
Ice Cover ◽  
Ocean General Circulation Model ◽  
Global Ocean ◽  
Ocean General Circulation ◽  
The Impact

A global ocean general circulation model has been coupled with a dynamic thermodynamic sea-ice model. This model has been spun-up in a 1000 year integration using daily atmosphere model data. Main water masses and currents are reproduced as well as the seasonal characteristics of the ice cover of the Northern and Southern Hemispheres. Model results for the Southern Ocean, however, show the ice cover as too thin, and there are large permanent polynyas in the Weddell and Ross Seas. These polynyas are due to a large upward oceanic heat flux caused by haline rejection during the freezing of sea ice. Sensitivity studies were performed to test several ways of treating the sea-surface salinity and the rejected brine. The impact on the ice cover, water-mass characteristics, and ocean circulation are described.

AMOC and Climate Responses to Dust Reduction and Greening of Sahara during the Mid-Holocene

2021 ◽  
pp. 1-59
Author(s):  
Ming Zhang ◽  
Yonggang Liu ◽  
Jian Zhang ◽  
Qin Wen
Keyword(s):  
Surface Temperature ◽  
North Africa ◽  
General Circulation ◽  
Circulation Model ◽  
Wind Farms ◽  
Ocean General Circulation Model ◽  
Climate Impact ◽  
Meridional Overturning Circulation ◽  
The Impact ◽  
Dust Reduction

AbstractThe North Africa was green during the mid-Holocene (6 ka) and emitting much less dust to the atmosphere than in present day. Here we use a fully coupled atmosphere-ocean general circulation model, CESM1.2.2, to test the impact of dust reduction and greening of Sahara on the Atlantic Meridional Overturning Circulation (AMOC) during this period. Results show that dust removal leads to a decrease of AMOC by 6.2 % while greening of Sahara with 100 % shrub (100 % grass) causes an enhancement of the AMOC by 6.1 % (4.8 %). The AMOC is increased by 5.3 % (2.3 %) when both the dust reduction and green Sahara with 100 % shrub (100 % grass) are considered. The AMOC changes are primarily due to the precipitation change over the west subtropical North Atlantic, from where the salinity anomaly is advected to the deepwater formation region. Global mean surface temperature increases by 0.09 °C and 0.40 °C (0.25 °C) when global dust is removed and when North Africa and Arabian region are covered by shrub (grass), respectively, showing a dominating effect of vegetation over dust. The comparison between modeled and reconstructed sea-surface temperature is improved when the effect of vegetation is considered. The results may have implication for climate impact of future wetting over North Africa, either through global warming or through building of solar farms and wind farms.

scholarly journals A new tool for model assessment in the frequency domain – Spectral Taylor Diagram : application to a global ocean general circulation model with tides

2018 ◽  
Author(s):  
Mabel Costa Calim ◽  
Paulo Nobre ◽  
Peter Oke ◽  
Andreas Schiller ◽  
Leo San Pedro Siqueira ◽  
...  
Keyword(s):  
Time Series ◽  
Frequency Domain ◽  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Global Ocean ◽  
Model Assessment ◽  
Taylor Diagram ◽  
Ocean General Circulation

Abstract. We introduce a new tool – the Spectral Taylor Diagram (STD) – for the comparison of time series in the frequency domain. The STD provides a novel way of displaying the squared-coherence, power, amplitude, phase, and root-mean-squared difference of discrete frequencies of two time-series. Each STD summarises these quantities in a single plot, for multiple targeted frequencies. The versatility of STDs is demonstrated through a series of sea-level comparisons between observations from tide gauges, and model results from a global eddy-permitting ocean general circulation model with explicit tidal forcing.

Impact of Orbital Parameters and Greenhouse Gas on the Climate of MIS 7 and MIS 5 Glacial Inceptions

2014 ◽  
Vol 27 (23) ◽  
pp. 8918-8933 ◽  
Author(s):  
Florence Colleoni ◽  
Simona Masina ◽  
Annalisa Cherchi ◽  
Doroteaciro Iovino
Keyword(s):  
Greenhouse Gas ◽  
General Circulation ◽  
Regional Scale ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Cold Climate ◽  
The Arctic ◽  
Orbital Parameters ◽  
The Impact ◽  
Mis 5

Abstract This work explores the impact of orbital parameters and greenhouse gas concentrations on the climate of marine isotope stage (MIS) 7 glacial inception and compares it to that of MIS 5. The authors use a coupled atmosphere–ocean general circulation model to simulate the mean climate state of six time slices at 115, 122, 125, 229, 236, and 239 kyr, representative of a climate evolution from interglacial to glacial inception conditions. The simulations are designed to separate the effects of orbital parameters from those of greenhouse gas (GHG). Their results show that, in all the time slices considered, MIS 7 boreal lands mean annual climate is colder than the MIS 5 one. This difference is explained at 70% by the impact of the MIS 7 GHG. While the impact of GHG over Northern Hemisphere is homogeneous, the difference in temperature between MIS 7 and MIS 5 due to orbital parameters differs regionally and is linked with the Arctic Oscillation. The perennial snow cover is larger in all the MIS 7 experiments compared to MIS 5, as a result of MIS 7 orbital parameters, strengthened by GHG. At regional scale, Eurasia exhibits the strongest response to MIS 7 cold climate with a perennial snow area 3 times larger than in MIS 5 experiments. This suggests that MIS 7 glacial inception is more favorable over this area than over North America. Furthermore, at 239 kyr, the perennial snow covers an area equivalent to that of MIS 5 glacial inception (115 kyr). The authors suggest that MIS 7 glacial inception is more extensive than MIS 5 glacial inception over the high latitudes.

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