Inter-annual Variability of the Current System off the West Greenland Coast from a very high-resolution numerical model

2022 ◽  
Author(s):  
Ruijian Gou ◽  
Clark Pennelly ◽  
Paul G. Myers
Keyword(s):  
High Resolution ◽  
Numerical Model ◽  
Current System ◽  
The West ◽  
West Greenland ◽  
Annual Variability ◽  
Very High

scholarly journals Mean Conditions and Seasonality of the West Greenland Boundary Current System near Cape Farewell

2020 ◽  
Vol 50 (10) ◽  
pp. 2849-2871
Author(s):  
Astrid Pacini ◽  
Robert S. Pickart ◽  
Frank Bahr ◽  
Daniel J. Torres ◽  
Andrée L. Ramsey ◽  
...  
Keyword(s):  
Current System ◽  
Labrador Sea ◽  
Western Boundary ◽  
Coastal Current ◽  
Boundary Current ◽  
The West ◽  
West Greenland ◽  
Irminger Sea ◽  
West Greenland Current ◽  
Recirculation Gyre

AbstractThe structure, transport, and seasonal variability of the West Greenland boundary current system near Cape Farewell are investigated using a high-resolution mooring array deployed from 2014 to 2018. The boundary current system is comprised of three components: the West Greenland Coastal Current, which advects cold and fresh Upper Polar Water (UPW); the West Greenland Current, which transports warm and salty Irminger Water (IW) along the upper slope and UPW at the surface; and the Deep Western Boundary Current, which advects dense overflow waters. Labrador Sea Water (LSW) is prevalent at the seaward side of the array within an offshore recirculation gyre and at the base of the West Greenland Current. The 4-yr mean transport of the full boundary current system is 31.1 ± 7.4 Sv (1 Sv ≡ 106 m3 s−1), with no clear seasonal signal. However, the individual water mass components exhibit seasonal cycles in hydrographic properties and transport. LSW penetrates the boundary current locally, through entrainment/mixing from the adjacent recirculation gyre, and also enters the current upstream in the Irminger Sea. IW is modified through air–sea interaction during winter along the length of its trajectory around the Irminger Sea, which converts some of the water to LSW. This, together with the seasonal increase in LSW entering the current, results in an anticorrelation in transport between these two water masses. The seasonality in UPW transport can be explained by remote wind forcing and subsequent adjustment via coastal trapped waves. Our results provide the first quantitatively robust observational description of the boundary current in the eastern Labrador Sea.

scholarly journals Very High-Resolution Infrared imagery of misaligned tungsten monoblock edge heating in the WEST tokamak

2021 ◽  
pp. 100910
Author(s):  
A. Grosjean ◽  
Y. Corre ◽  
J. Gaspar ◽  
J.P. Gunn ◽  
S. Carpentier ◽  
...  
Keyword(s):  
High Resolution ◽  
Infrared Imagery ◽  
The West ◽  
Very High

scholarly journals RECONSTRUCTION OF THE SLIP DISTRIBUTION ALONG THE WEST HELANSHAN FAULT, NORTHERN CHINA BASED ON HIGH-RESOLUTION TOPOGRAPHY

2020 ◽  
Vol XLIII-B2-2020 ◽  
pp. 1025-1031
Author(s):  
H. Bi ◽  
W. Zheng ◽  
Q. Lei ◽  
J. Zeng
Keyword(s):  
High Resolution ◽  
Active Fault ◽  
Northern China ◽  
Strike Slip ◽  
The Tibetan Plateau ◽  
The West ◽  
Rupture Length ◽  
Vertical Displacements ◽  
Significant Length ◽  
Very High

Abstract. The increasing wealthy of high-resolution topography allows for remotely measuring and analysing offset features and their associated surface slip distributions at a very high resolution and along a significant length of a fault, hence providing important insights into many aspects of the fault behaviour. The West Helanshan Fault is a Holocene active fault located at the junction of the Tibetan Plateau, Alashan, and Ordos blocks. Despite its special tectonic location, it has rarely been studied before. In this study, a 2-m-resolution DEM of the West Helanshan Fault was built from the high-resolution (0.5 m) WorldView-3 stereo satellite imagery based on the photogrammetry method, and a total of 181 strike-slip offsets and 201 vertical displacements were acquired along different segments of the fault. By statistical analysis of the offset observations, we conclude that at least six large paleoearthquakes have ruptured the fault, producing a minimum rupture length of ∼50 km, and the paleoearthquakes have followed a characteristic slip pattern with a coseismic strike slip of ∼3 m and a vertical slip of ∼1 m, corresponding to a geologic moment magnitude of 7.1–7.5.

scholarly journals Cyclonic eddies in the West Greenland boundary current system

2021 ◽  
Author(s):  
Astrid Pacini ◽  
Robert S. Pickart ◽  
Isabela A. Le Bras ◽  
Fiammetta Straneo ◽  
N. Penny Holliday ◽  
...  
Keyword(s):  
North Atlantic ◽  
Current System ◽  
Deep Convection ◽  
Labrador Sea ◽  
Boundary Current ◽  
The West ◽  
West Greenland ◽  
Denmark Strait ◽  
First Time ◽  
Insight Into

<p>The Labrador Sea is an important site for deep convection, and the boundary current surrounding the Sea impacts the strength of this convection and the subsequent restratification. As part of the Overturning of the Subpolar North Atlantic Program, ten moorings have been maintained on the West Greenland shelf and slope that provide hourly, high-resolution renderings of the boundary current. These data reveal the presence and propagation of abundant mid-depth intensified cyclonic eddies, which have not previously been documented in the West Greenland boundary current system. This study quantifies these features and their structure and demonstrates that they are the downstream manifestation of Denmark Strait Overflow Water (DSOW) cyclones. Using the mooring data, the statistics of these features are presented, a composite eddy is constructed, and the velocity and transport structure are described. A synoptic survey of the region captured two of these features, and provides further insight into their structure and timing. This is the first time DSOW cyclones have been observed in the Labrador Sea, and their presence, propagation, and transport must be accounted for in order to assess their contribution to the heat and freshwater budgets of the Labrador Sea interior.</p>

scholarly journals Cyclonic eddies in the West Greenland Boundary Current System

2021 ◽  
Author(s):  
Astrid Pacini ◽  
Robert S. Pickart ◽  
Isabela A. Le Bras ◽  
Fiammetta Straneo ◽  
N.P. Holliday ◽  
...  
Keyword(s):  
Propagation Velocity ◽  
Current System ◽  
Labrador Sea ◽  
Boundary Current ◽  
The West ◽  
West Greenland ◽  
Irminger Sea ◽  
Denmark Strait ◽  
Integral Role ◽  
Thick Lens

AbstractThe boundary current system in the Labrador Sea plays an integral role in modulating convection in the interior basin. Four years of mooring data from the eastern Labrador Sea reveal persistent mesoscale variability in the West Greenland boundary current. Between 2014 and 2018, 197 mid-depth intensified cyclones were identified that passed the array near the 2000 m isobath. In this study, we quantify these features and show that they are the downstream manifestation of Denmark Strait Overflow Water (DSOW) cyclones. A composite cyclone is constructed revealing an average radius of 9 km, maximum azimuthal speed of 24 cm/s, and a core propagation velocity of 27 cm/s. The core propagation velocity is significantly smaller than upstream near Denmark Strait, allowing them to trap more water. The cyclones transport a 200-m thick lens of dense water at the bottom of the water column, and increase the transport of DSOW in the West Greenland boundary current by 17% relative to the background flow. Only a portion of the features generated at Denmark Strait make it to the Labrador Sea, implying that the remainder are shed into the interior Irminger Sea, are retroflected at Cape Farewell, or dissipate. A synoptic shipboard survey east of Cape Farewell, conducted in summer 2020, captured two of these features which shed further light on their structure and timing. This is the first time DSOW cyclones have been observed in the Labrador Sea—a discovery that could have important implications for interior stratification.

scholarly journals Structure, variability, and dynamics of the West Greenland Boundary Current System

2022 ◽  
Author(s):  
◽  
Astrid Pacini
Keyword(s):  
Current System ◽  
Meridional Overturning Circulation ◽  
Labrador Sea ◽  
Small Scale ◽  
Western Boundary ◽  
Coastal Current ◽  
Boundary Current ◽  
The West ◽  
West Greenland ◽  
Atlantic Origin

The ventilation of intermediate waters in the Labrador Sea has important implications for the strength of the Atlantic Meridional Overturning Circulation. Boundary current-interior interactions regulate the exchange of properties between the slope and the basin, which in turn regulates the magnitude of interior convection and the export of ventilated waters from the subpolar gyre. This thesis characterizes theWest Greenland Boundary Current System near Cape Farewell across a range of spatio-temporal scales. The boundary current system is composed of three velocity cores: (1) the West Greenland Coastal Current (WGCC), transporting Greenland and Arctic meltwaters on the shelf; (2) the West Greenland Current (WGC), which advects warm, saline Atlantic-origin water at depth, meltwaters at the surface, and newly-ventilated Labrador Sea Water (LSW); and (3) the Deep Western Boundary Current, which carries dense overflow waters ventilated in the Nordic Seas. The seasonal presence of the LSW and Atlantic-origin water are dictated by air-sea buoyancy forcing, while the seasonality of the WGCC is governed by remote wind forcing and the propagation of coastally trapped waves from East Greenland. Using mooring data and hydrographic surveys, we demonstrate mid-depth intensified cyclones generated at Denmark Strait are found offshore of the WGC and enhance the overflow water transport at synoptic timescales. Using mooring, hydrographic, and satellite data, we demonstrate that the WGC undergoes extensive meandering due to baroclinic instability that is enhanced in winter due to LSW formation adjacent to the current. This leads to the production of small-scale, anticyclonic eddies that can account for the entirety of wintertime heat loss within the Labrador Sea. The meanders are shown to trigger the formation of Irminger Rings downstream. Using mooring, hydrographic, atmospheric, and Lagrangian data, and a mixing model, we find that strong atmospheric storms known as forward tip jets cause upwelling at the shelfbreak that triggers offshore export of freshwater. This freshwater flux can explain the observed lack of ventilation in the eastern Labrador Sea. Together, this thesis documents previously unobserved interannual, seasonal, and synoptic-scale variability and dynamics within the West Greenland boundary current system that must be accounted for in future modeling.

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