Interaction Between Mesoscale Eddies and the Gyre Circulation in the Lofoten Basin

Raj, Roshin P.; Halo, Issufo; Chatterjee, Sourav; Белоненко, Т. В.; Bakhoday-Paskyabi, Mostafa; Bashmachnikov, Igor; Федоров, А. В.; Xie, Jiping

doi:10.1029/2020jc016102

Cited by 16 publications

(17 citation statements)

References 59 publications

(111 reference statements)

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“…The area in which the Norwegian Slope Current core is located is characterized by negative BT values in its western periphery and positive in the eastern one. A detailed analysis of this phenomenon is presented in [32].…”

Section: Resultsmentioning

confidence: 99%

Study of the Mechanisms of Vortex Variability in the Lofoten Basin Based on Energy Analysis

Travkin¹,

Белоненко²

2021

PhO

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Purpose. The Lofoten Basin is one of the most energetic zones of the World Ocean characterized by high activity of mesoscale eddies. The study is aimed at analyzing different components of general energy in the basin, namely the mean kinetic and vortex kinetic energy calculated using the integral of the volume of available potential and kinetic energy of the Lofoten Vortex, as well as variability of these characteristics. Methods and Results. GLORYS12V1 reanalysis data for the period 2010–2018 were used. The mean kinetic energy and the eddy kinetic one were analyzed; and as for the Lofoten Vortex, its volume available potential and kinetic energy was studied. Mesoscale activity of eddies in winter is higher than in summer. Evolution of the available potential energy and kinetic energy of the Lofoten Vortex up to the 1000 m horizon was studied. It is shown that the vortex available potential energy exceeds the kinetic one by an order of magnitude, and there is a positive trend with the coefficient 0,23·1015 J/year. It was found that in the Lofoten Basin, the intermediate layer from 600 to 900 m made the largest contribution to the potential energy, whereas the 0–400 m layer – to kinetic energy. The conversion rates of the mean kinetic energy into the vortex kinetic one, and the mean available potential energy into the vortex available potential one (baroclinic and barotropic instability) were analyzed. It is shown that the first type of transformation dominates in summer, while the second one is characterized by its increase in winter. Conclusions. The vertical profile shows that kinetic energy of eddies in winter is higher than in summer. The available potential energy of a vortex is by an order of magnitude greater than the kinetic energy. Increase in the available potential energy is confirmed by a significant positive trend and by decrease of the vortex Burger number. The graphs of the barotropic instability conversion rate demonstrate the multidirectional flows in the vortex zone with the dipole structure observed in a winter period, and the tripole one – in summer. The barotropic instability highest intensity is observed in summer. The baroclinic instability is characterized by intensification of the regime in winter that is associated with weakening of stratification in this period owing to winter convection.

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Section: Resultsmentioning

confidence: 99%

Study of the Mechanisms of Vortex Variability in the Lofoten Basin Based on Energy Analysis

Travkin¹,

Белоненко²

2021

PhO

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“…The first dominates in the northern part of the study region (west of Spitsbergen), while the secondin its southern part (the Lofoten Basin). The imbalances form from 10 to 20% of the incoming heat and encompass the heat fluxes by the mesoscale eddies (Raj et al, 2020;Bashmachnikov et al, 2020). The imbalances lead to the observed warming of the eastern Nordic Seas.…”

Section: Discussionmentioning

confidence: 99%

The coherence of the oceanic heat transport through the Nordic seas: oceanic heat budget and interannual variability

Vesman

Bashmachnikov

Golubkin

et al. 2020

Preprint

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Abstract. Atlantic Water is the main source of the heat and salt in the Arctic. On the way to the Arctic Ocean via the Nordic Seas, it interacts and mixes with other water masses which affects sea ice extent and deep water formation. The Atlantic Water heat transported into the Nordic Seas has a significant impact on the local climate and is investigated here along with its inter-annual variability using the ARMOR3D dataset, which is a collection of 3D monthly temperature, salinity and geostrophic velocities fields, derived from in situ and satellite data on a regular grid since 1993. The study region includes the eastern part of the Nordic seas, i.e., seven latitudinal transects from Svinoy section (65° N) to the northern part of the Fram Strait (78.8° N). The Atlantic Water heat advection decreases northwards, as a significant amount of heat is lost to the atmosphere and due to mixing with surrounding waters. As observed, the imbalance of heat fluxes in the upper layer leads to an increase in the upper ocean mean temperature over most of the study region. The correlations of the interannual variations of the advective heat fluxes rapidly drop from Svinoy to Jan Mayen sections and between Bear Island and Sorkapp sections. This is a result of a differential damping of periodicities (the 2–3 year and 5–6 year oscillations), as well as of different signs of the tendencies over the latest decades. The heat fluxes at all sections show a consistent change with meridional (C) and western (W) weather types, which is due to the different direction of the Ekman pumping associated with each of the weather types. A certain link to the NAO, AO and EA atmospheric indices is observed only at the southern sections.

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“…1 for approximate locations of the regions). These regions have exhibited strong-negative-SIC trends during recent decades (Rogers and Hung, 2008; see also Fig. 1a in Selyuzhenok et al, 2020).…”

Section: Introductionmentioning

confidence: 94%

Combined influence of oceanic and atmospheric circulations on Greenland sea ice concentration

et al. 2021

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Abstract. The amount and spatial extent of Greenland Sea (GS) ice are primarily controlled by the sea ice export across the Fram Strait (FS) and by local seasonal sea ice formation, melting, and sea ice dynamics. In this study, using satellite passive microwave sea ice observations, atmospheric and a coupled ocean-sea ice reanalysis system, TOPAZ4, we show that both the atmospheric and oceanic circulation in the Nordic Seas (NS) act in tandem to explain the SIC variability in the south-western GS. Northerly wind anomalies associated with anomalously low sea level pressure (SLP) over the NS reduce the sea ice export in the south-western GS due to westward Ekman drift of sea ice. On the other hand, the positive wind stress curl strengthens the cyclonic Greenland Sea Gyre (GSG) circulation in the central GS. An intensified GSG circulation may result in stronger Ekman divergence of surface cold and fresh waters away from the south-western GS. Both of these processes can reduce the freshwater content and weaken the upper-ocean stratification in the south-western GS. At the same time, warm and saline Atlantic Water (AW) anomalies are recirculated from the FS region to the south-western GS by a stronger GSG circulation. Under weakly stratified conditions, enhanced vertical mixing of these subsurface AW anomalies can warm the surface waters and inhibit new sea ice formation, further reducing the SIC in the south-western GS.

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Interaction Between Mesoscale Eddies and the Gyre Circulation in the Lofoten Basin

Cited by 16 publications

References 59 publications

Study of the Mechanisms of Vortex Variability in the Lofoten Basin Based on Energy Analysis

Study of the Mechanisms of Vortex Variability in the Lofoten Basin Based on Energy Analysis

The coherence of the oceanic heat transport through the Nordic seas: oceanic heat budget and interannual variability

Combined influence of oceanic and atmospheric circulations on Greenland sea ice concentration

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