Spreading dynamics of central Labrador and Irminger Sea Waters

2020 ◽  
Author(s):  
Patricia Handmann ◽  
Martin Visbeck ◽  
Arne Biastoch
Keyword(s):  
High Resolution ◽  
Ocean Model ◽  
Shelf Break ◽  
Labrador Sea ◽  
Mean Velocity ◽  
The North ◽  
Irminger Sea ◽  
First Results ◽  
Resolution Model ◽  
High Resolution Model

<p>Water mass formation in the Subpolar North Atlantic and successive southward export, connects high latitudes with lower latitudes, as a part of the lower Atlantic meridional overturning (AMOC) limb. The role of regional importance, in particular the respective roles of the Labrador and Irminger Sea, in this process are in debate. </p><p>This study analyses pathways connecting the Labrador and Irminger Sea in detail, using simulated Lagrangian particle trajectories. To give further insight on interconnectivity and flow patterns we used two setups with different velocity fields, a high-resolution ocean model (VIKING20X) and a gridded Argo float displacement climatology. Both setups indicate two distinct pathways with interconnectivity on the order of 20% of the total amount of seeded particles between the Labrador Sea and Irminger Sea. One pathway is following the recirculation in the Labrador Sea along the Greenland shelf break; the other is along the Newfoundland shelf break turning to the north/northwest at the Orphan-Knoll region towards the central Irminger Sea. For the Argo based advective-diffusive particle trajectory integration a 2.5–3.5 year travel time scale was derived between the Labrador and the Irminger Sea, while the experiments with the temporarily varying high-resolution model output revealed significantly shorter spreading times of about 1.5–2 years. While both pathways are represented in either setup, the pathway following the Newfoundland shelf break is populated stronger in the model-based experiments. In general we found that connectivity between the two regions is weaker in the experiments based on the climatological mean velocity output of the model than in those based on the Argo derived fields, first results indicate that this is due to stronger boundary currents and a weaker recirculation in the Labrador Sea.</p>

Dissecting the Barotropic Transport in a High-resolution ocean model

2020 ◽  
Author(s):  
Martin Claus ◽  
Yuan Wang ◽  
Richard Greatbatch ◽  
Jinyu Sheng
Keyword(s):  
High Resolution ◽  
North Atlantic ◽  
Spatial Scales ◽  
Ocean Model ◽  
Water Model ◽  
North Atlantic Current ◽  
The North ◽  
Circulation Patterns ◽  
Resolution Model ◽  
High Resolution Model

<p>We present a method to decompose the time mean vertically averaged transport, as simulated by an high-resolution ocean model, into its four dominant components. These components are driven by the gradient of potential energy per unit area (PE), the divergence of the flux of time mean momentum (MMF) and eddy momentum (EMF), and the wind stress. Since the local vorticity budget and the bathymetry are noisy and dominated by small spatial scales, a barotropic shallow water model is used as a filter to diagnose the respective transports instead of integrating along lines of constant f/H.<br>Applying this method to the output of a high-resolution model of the North Atlantic we find that PE is the most important driver, including the northwest corner. MMF is an important driver of transport around the Labrador Sea continental slope and, together with the EMF, it drives significant transport along the path of the Gulf Stream and North Atlantic current. Additionally, the circulation patterns driven by the EMF compares well with an estimate based on a satellite product. Hence, the presented method provides insights into the relative importance of the different dynamical processes that may drive barotropic transport in an ocean model. But it may also be used to isolate potential issues if a model misrepresents the barotropic transport.</p>

scholarly journals High-Resolution Ocean Model Captures Large-Scale Heat Transport

Eos ◽  
2016 ◽  
Author(s):  
Sarah Stanley
Keyword(s):  
High Resolution ◽  
Heat Transport ◽  
North Atlantic ◽  
Large Scale ◽  
Ocean Model ◽  
Sea Surface ◽  
The North ◽  
Resolution Model ◽  
High Resolution Model ◽  
The North Atlantic

A lower-resolution model is sufficient to capture air-sea interactions, but a high-resolution model better simulates average sea surface temperatures in the North Atlantic.

scholarly journals Effects of High Resolution and Spinup Time on Modeled North Atlantic Circulation

2019 ◽  
Vol 49 (5) ◽  
pp. 1159-1181 ◽  
Author(s):  
Christopher Danek ◽  
Patrick Scholz ◽  
Gerrit Lohmann
Keyword(s):  
High Resolution ◽  
North Atlantic ◽  
Horizontal Resolution ◽  
Quasi Equilibrium ◽  
Low Resolution ◽  
The North ◽  
Resolution Model ◽  
High Horizontal Resolution ◽  
High Resolution Model ◽  
The North Atlantic

AbstractThe influence of a high horizontal resolution (5–15 km) on the general circulation and hydrography in the North Atlantic is investigated using the Finite Element Sea Ice–Ocean Model (FESOM). We find a stronger shift of the upper-ocean circulation and water mass properties during the model spinup in the high-resolution model version compared to the low-resolution (~1°) control run. In quasi equilibrium, the high-resolution model is able to reduce typical low-resolution model biases. Especially, it exhibits a weaker salinification of the North Atlantic subpolar gyre and a reduced mixed layer depth in the Labrador Sea. However, during the spinup adjustment, we see that initially improved high-resolution features partially reduce over time: the strength of the Atlantic overturning and the path of the North Atlantic Current are not maintained, and hence hydrographic biases known from low-resolution ocean models return in the high-resolution quasi-equilibrium state. We identify long baroclinic Rossby waves as a potential cause for the strong upper-ocean adjustment of the high-resolution model and conclude that a high horizontal resolution improves the state of the modeled ocean but the model integration length should be chosen carefully.

Mesoscale eddy statistics and implications for parameterization refinements from a diagnosis of a high resolution model of the North Pacific

2010 ◽  
Vol 33 (3-4) ◽  
pp. 205-223 ◽  
Author(s):  
Hiroyuki Tsujino ◽  
Shiro Nishikawa ◽  
Kei Sakamoto ◽  
Hideyuki Nakano ◽  
Hiroshi Ishizaki
Keyword(s):  
High Resolution ◽  
North Pacific ◽  
Mesoscale Eddy ◽  
The North ◽  
Resolution Model ◽  
High Resolution Model ◽  
The North Pacific

scholarly journals Towards Direct Simulation of Future Tropical Cyclone Statistics in a High-Resolution Global Atmospheric Model

2010 ◽  
Vol 2010 ◽  
pp. 1-13 ◽  
Author(s):  
Michael F. Wehner ◽  
G. Bala ◽  
Phillip Duffy ◽  
Arthur A. Mirin ◽  
Raquel Romano
Keyword(s):  
High Resolution ◽  
Radiative Forcing ◽  
General Circulation ◽  
Circulation Model ◽  
Atmospheric Model ◽  
Tropical Storm ◽  
Model Studies ◽  
The North ◽  
Resolution Model ◽  
High Resolution Model

We present a set of high-resolution global atmospheric general circulation model (AGCM) simulations focusing on the model's ability to represent tropical storms and their statistics. We find that the model produces storms of hurricane strength with realistic dynamical features. We also find that tropical storm statistics are reasonable, both globally and in the north Atlantic, when compared to recent observations. The sensitivity of simulated tropical storm statistics to increases in sea surface temperature (SST) is also investigated, revealing that a credible late 21st century SST increase produced increases in simulated tropical storm numbers and intensities in all ocean basins. While this paper supports previous high-resolution model and theoretical findings that the frequency of very intense storms will increase in a warmer climate, it differs notably from previous medium and high-resolution model studies that show a global reduction in total tropical storm frequency. However, we are quick to point out that this particular model finding remains speculative due to a lack of radiative forcing changes in our time-slice experiments as well as a focus on the Northern hemisphere tropical storm seasons.

scholarly journals Flow paths and variability of the North Atlantic Current: A comparison of observations and a high-resolution model

2017 ◽  
Vol 122 (4) ◽  
pp. 2686-2708 ◽  
Author(s):  
Tilia Breckenfelder ◽  
Monika Rhein ◽  
Achim Roessler ◽  
Claus W. Böning ◽  
Arne Biastoch ◽  
...  
Keyword(s):  
High Resolution ◽  
North Atlantic ◽  
North Atlantic Current ◽  
Flow Paths ◽  
The North ◽  
Resolution Model ◽  
High Resolution Model ◽  
The North Atlantic ◽  
Atlantic Current

scholarly journals Changing spatial patterns of deep convection in the subpolar North Atlantic

2021 ◽  
Author(s):  
Siren Rühs ◽  
Eric Oliver ◽  
Arne Biastoch ◽  
Claus W. Böning ◽  
Michael Dowd ◽  
...  
Keyword(s):  
North Atlantic ◽  
Deep Convection ◽  
Ocean Model ◽  
Labrador Sea ◽  
Recent Event ◽  
Near Surface ◽  
The North ◽  
Relative Contribution ◽  
Irminger Sea ◽  
The North Atlantic Oscillation

<p>Deep convection and associated deep water formation are key processes for climate variability, since they impact the oceanic uptake of heat and trace gases and alter the structure and strength of the global overturning circulation. For long, deep convection in the subpolar North Atlantic was thought to be confined to the central Labrador Sea in the western subpolar gyre (SPG). However, there is increasing evidence that deep convection also occurs in the eastern SPG south of Cape Farewell and in the Irminger Sea. In particular, observations indicate gyre-scale intensified convection in 2015-2018. Here we assess this recent event in the context of the temporal evolution of the spatial deep convection pattern in the SPG since the mid-twentieth century, using realistic eddy-rich ocean model simulations. These reveal large interannual variability, including several periods with intensified deep convection in the eastern SPG. Notably, this happened in 2015-2018, but to a lesser degree in the late 1980s to early 1990s, the period with highest deep convection intensity in the Labrador Sea related to a persistent positive phase of the North Atlantic Oscillation. Our analyses further suggest that deep convection in 2015-2018 occurred with an unprecedented high (low) relative contribution of the eastern (western) SPG to the total deep convection volume. This is partly linked to a considerable smaller north-westward extent of deep convection in the Labrador Sea compared to previous periods of intensified deep convection, and may be a first fingerprint of strong near-surface freshening in the Labrador Sea associated with Greenland melting.</p>

scholarly journals Comparison of extended and ensemble based Kalman filters with low and high resolution primitive equation ocean models

2005 ◽  
Vol 12 (5) ◽  
pp. 755-765 ◽  
Author(s):  
I. Hoteit ◽  
G. Korres ◽  
G. Triantafyllou
Keyword(s):  
High Resolution ◽  
Kalman Filters ◽  
Linear Analysis ◽  
Ocean Model ◽  
Primitive Equation ◽  
Gaussian Distributions ◽  
Resolution Model ◽  
High Resolution Model ◽  
Ocean Models ◽  
Very High

Abstract. Kalman filters are widely used for data assimilation into ocean models. The aim of this study is to discuss the relevance of these filters with high resolution ocean models. This was investigated through the comparison of two advanced Kalman filters: the singular evolutive extended Kalman (SEEK) filter and its ensemble-based variant, called SEIK filter. The two filters were implemented with the Princeton Ocean model (POM) considering a low spatial resolution configuration (Mediterranean sea model) and a very high one (Pagasitikos Gulf coastal model). It is shown that the two filters perform reasonably well when applied with the low resolution model. However, when the high resolution model is considered, the behavior of the SEEK filter seriously degrades because of strong model nonlinearities while the SEIK filter remains remarkably more stable. Based on the assumption of prior Gaussian distributions, the linear analysis step of the latter can still be improved though.

scholarly journals Hydrodynamic variability in the Southern Bight of the North Sea in response to typical atmospheric and tidal regimes. Benefit of using a high resolution model

2020 ◽  
Vol 154 ◽  
pp. 101682
Author(s):  
Evgeny Ivanov ◽  
Arthur Capet ◽  
Alexander Barth ◽  
Eric J.M. Delhez ◽  
Karline Soetaert ◽  
...  
Keyword(s):  
High Resolution ◽  
North Sea ◽  
Southern Bight ◽  
The North ◽  
Resolution Model ◽  
The North Sea ◽  
High Resolution Model
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