scholarly journals Space and time scales of mesoscale motion in the western North Atlantic

2018 ◽  
Author(s):  
James G. Richman ◽  
Carl Wunsch ◽  
Nelson G. Hogg
Keyword(s):  
Time Scales ◽  
North Atlantic ◽  
Space And Time ◽  
Mesoscale Motion

scholarly journals Space and time scales of mesoscale motion in the western North Atlantic

1977 ◽  
Vol 15 (4) ◽  
pp. 385 ◽  
Author(s):  
James G. Richman ◽  
Carl Wunsch ◽  
Nelson G. Hogg
Keyword(s):  
Time Scales ◽  
North Atlantic ◽  
Space And Time ◽  
Mesoscale Motion

scholarly journals Locally and Remotely Forced Subtropical AMOC Variability: A Matter of Time Scales

2020 ◽  
Vol 33 (12) ◽  
pp. 5155-5172
Author(s):  
Quentin Jamet ◽  
William K. Dewar ◽  
Nicolas Wienders ◽  
Bruno Deremble ◽  
Sally Close ◽  
...  
Keyword(s):  
Time Series ◽  
Time Scales ◽  
North Atlantic ◽  
Time Scale ◽  
Low Frequency ◽  
Meridional Overturning Circulation ◽  
Open Boundary ◽  
Overturning Circulation ◽  
Decadal Scale ◽  
Meridional Overturning

AbstractMechanisms driving the North Atlantic meridional overturning circulation (AMOC) variability at low frequency are of central interest for accurate climate predictions. Although the subpolar gyre region has been identified as a preferred place for generating climate time-scale signals, their southward propagation remains under consideration, complicating the interpretation of the observed time series provided by the Rapid Climate Change–Meridional Overturning Circulation and Heatflux Array–Western Boundary Time Series (RAPID–MOCHA–WBTS) program. In this study, we aim at disentangling the respective contribution of the local atmospheric forcing from signals of remote origin for the subtropical low-frequency AMOC variability. We analyze for this a set of four ensembles of a regional (20°S–55°N), eddy-resolving (1/12°) North Atlantic oceanic configuration, where surface forcing and open boundary conditions are alternatively permuted from fully varying (realistic) to yearly repeating signals. Their analysis reveals the predominance of local, atmospherically forced signal at interannual time scales (2–10 years), whereas signals imposed by the boundaries are responsible for the decadal (10–30 years) part of the spectrum. Due to this marked time-scale separation, we show that, although the intergyre region exhibits peculiarities, most of the subtropical AMOC variability can be understood as a linear superposition of these two signals. Finally, we find that the decadal-scale, boundary-forced AMOC variability has both northern and southern origins, although the former dominates over the latter, including at the site of the RAPID array (26.5°N).

Microclimate through space and time: Microclimatic variation at the edge of regeneration forests over daily, yearly and decadal time scales

2014 ◽  
Vol 334 ◽  
pp. 174-184 ◽  
Author(s):  
Thomas P. Baker ◽  
Gregory J. Jordan ◽  
E. Ashley Steel ◽  
Nicholas M. Fountain-Jones ◽  
Timothy J. Wardlaw ◽  
...  
Keyword(s):  
Time Scales ◽  
Space And Time

Propagation of Thermohaline Anomalies and their predictive potential in the Northern North Atlantic

2021 ◽  
Author(s):  
Helene R. Langehaug ◽  
Pablo Ortega ◽  
Francois Counillon ◽  
Daniela Matei ◽  
Elizabeth Maroon ◽  
...  
Keyword(s):  
Time Scales ◽  
North Atlantic ◽  
Atlantic Water ◽  
The Arctic ◽  
Lead Times ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Predictive Skill ◽  
Prediction Systems ◽  
Water Pathway

<p>In this study we assess to what extent seven different dynamical prediction systems can retrospectively predict the winter sea surface temperature (SST) in the subpolar North Atlantic and the Nordic Seas in the time period 1970-2005. We focus in particular on the region where warm water flows poleward, i.e., the Atlantic water pathway, and on interannual-to-decadal time scales. To better understand why dynamical prediction systems have predictive skill or lack thereof, we confront them with a mechanism identified from observations – propagation of oceanic anomalies from low to high latitudes – on different forecast lead times. This observed mechanism shows that warm and cold anomalies propagate along the Atlantic water pathway within a certain time frame. A key result from this study is that most models have difficulty representing this mechanism, resulting in an overall poor prediction skill after 1-2 years lead times (after applying a band-pass filter to focus on interannual-to-decadal time scales). There is a link, although not very strong, between predictive skill and the representation of the SST propagation. Observational studies demonstrate predictability several years in advance in this region, thus suggesting a great potential for improvement of dynamical climate predictions by resolving the causes for the misrepresentation of the oceanic link. Inter model differences in simulating surface velocities along the Atlantic water pathway suggest that realistic velocities are important to better circulate anomalies poleward, and hence, increase predictive skill on interannual-to-decadal time scales in the oceanic gateway to the Arctic.</p>

scholarly journals Propagation of North Atlantic Deep Water Anomalies

2018 ◽  
Vol 48 (8) ◽  
pp. 1831-1848 ◽  
Author(s):  
David Nieves ◽  
Michael Spall
Keyword(s):  
Boundary Condition ◽  
Layer Thickness ◽  
Time Scales ◽  
North Atlantic ◽  
Deep Water ◽  
Volume Flux ◽  
Reduced Gravity ◽  
Northern Boundary ◽  
Variable Source ◽  
Gravity Equations

AbstractWe present a simplified theory using reduced-gravity equations for North Atlantic Deep Water (NADW) and its variation driven by high-latitude deep-water formation. The theory approximates layer thickness on the eastern boundary with domain-averaged layer thickness and, in tandem with a mass conservation argument, retains fundamental physics for cross-equatorial flows on interannual and longer forcing time scales. Layer thickness anomalies are driven by a time-dependent northern boundary condition that imposes a southward volume flux representative of a variable source of NADW and damped by diapycnal mixing throughout the basin. Moreover, an outflowing southern boundary condition imposes a southward volume flux that generally differs from the volume flux at the northern boundary, giving rise to temporal storage of NADW within the Atlantic basin. Closed form analytic solutions for the amplitude and phase are provided when the variable source of NADW is sinusoidal. We provide a nondimensional analysis that demonstrates that solution behavior is primarily controlled by two parameters that characterize the meridional extent of the southern basin and the width of the basin relative to the equatorial deformation radius. Similar scaling applied to the time-lagged equations of Johnson and Marshall provides a clear connection to their results. Numerical simulations of reduced-gravity equations agree with analytic predictions in linear, turbulent, and diabatic regimes. The theory introduces a simple analytic framework for studying idealized buoyancy- and wind-driven cross-equatorial flows on interannual and longer time scales.

scholarly journals Interannual modulation of extratropical high frequency variability

1997 ◽  
Vol 40 (4) ◽  
Author(s):  
R. Caballero
Keyword(s):  
Normal Mode ◽  
Time Scales ◽  
High Frequency ◽  
Spherical Geometry ◽  
Simple Explanation ◽  
Space And Time ◽  
High Frequency Variability ◽  
Hemisphere Winter ◽  
Selection Of

A simple explanation is presented for the observed interannual changes in the dominant space and time scales of Northem Hemisphere winter extratropical high frequency variability. It is found that such changes can suc- cessfully be predicted by linearizing a 2-level quasi-geostrophic mode] in spherical geometry around the ob- served zona] mean states. The mechanisms responsible for the selection of the most unstable normal mode are investigated.

Transfers through argillaceous rocks over large space and time scales: Insights given by water stable isotopes

2008 ◽  
Vol 33 ◽  
pp. S67-S74 ◽  
Author(s):  
S. Savoye ◽  
J.-L. Michelot ◽  
F. Bensenouci ◽  
J.-M. Matray ◽  
J. Cabrera
Keyword(s):  
Stable Isotopes ◽  
Time Scales ◽  
Large Space ◽  
Space And Time ◽  
Argillaceous Rocks
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