Lateral redistribution of heat and salt in the Nordic Seas

Spall, Michael A.; Almansi, Mattia; Huang, Jin‐ding; Haine, Thomas W. N.; Pickart, Robert S.

doi:10.1016/j.pocean.2021.102609

Cited by 11 publications

(15 citation statements)

References 61 publications

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“…Furthermore, eddies might not be the only processes that are playing a role in high-resolution models. Indeed, Schulze Chretien and Frajka-Williams (2018) recently suggested that the freshwater transport from the shelves into the central Labrador Sea in the first top 30 meters might be largely due to wind-driven Ekman transport in the West Greenland Current, a process that is strongly dependent on the representation of the regional-scale energetic winds in the atmosphere (e.g., Spall et al, 2021), and is therefore poorly represented in LR models. Also, the finer scales resolved in the HR model allow to better represent the boundary currents, which are channeling most of the freshwater transport over the shelf around Greenland.…”

Section: Discussionmentioning

confidence: 99%

AMOC Recent and Future Trends: A Crucial Role for Oceanic Resolution and Greenland Melting?

et al. 2022

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The Atlantic Meridional Overturning Circulation (AMOC) is a crucial element of the Earth climate. It is a complex circulation system difficult to monitor and to model. There is considerable debate regarding its evolution over the last century as well as large uncertainty about its fate at the end of this century. We depict here the progress since the IPCC SROCC report, offering an update of its chapter 6.7. We also show new results from a high-resolution ocean model and a CMIP6 model to investigate the impact of Greenland Ice Sheet (GrIS) melting, a key uncertainty for past and future AMOC changes. The ocean-only simulation at 1/24° resolution in the Arctic-North Atlantic Ocean performed over the period 2004–2016 indicates that the spread of the Greenland freshwater runoff toward the center of the Labrador Sea, where oceanic convection occurs, seems larger in this model than in a CMIP6 model. Potential explanations are related to the model spatial resolution and the representation of mesoscale processes, which more realistically transport the freshwater released around the shelves and, through eddies, provides strong lateral exchanges between the fine-scale boundary current and the convective basin in the Labrador Sea. The larger freshening of the Labrador Sea in the high-resolution model then strongly affects deep convection activity. In the simulation including GrIS melting, the AMOC weakens by about 2 Sv after only 13 years, far more strongly than what is found in the CMIP6 model. This difference raises serious concerns on the ability of CMIP6 models to correctly assess the potential impact of GrIS melting on the AMOC changes over the last few decades as well as on its future fate. To gain confidence in the GrIS freshwater impacts on climate simulations and therefore in AMOC projections, urgent progress should be made on the parameterization of mesoscale processes in ocean models.

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Section: Discussionmentioning

confidence: 99%

AMOC Recent and Future Trends: A Crucial Role for Oceanic Resolution and Greenland Melting?

et al. 2022

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“…What led to these changes? Våge et al (2018) and Spall et al (2021) suggested that strong northerly winds in winter can divert the surface fresh water onto the Greenland shelf via enhanced onshore Ekman transport. To examine this, we estimated the onshore Ekman transport displacement (Equation 1 in Section 2.4) over the time period between the occupation of the two sections.…”

Section: Water Column Response To a Cold-air Outbreakmentioning

confidence: 99%

Wintertime Water Mass Transformation in the Western Iceland and Greenland Seas

et al. 2021

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Hydrographic and velocity data from a 2018 winter survey of the western Iceland and Greenland Seas are used to investigate the ventilation of overflow water feeding Denmark Strait. We focus on the two general classes of overflow water: warm, saline Atlantic‐origin Overflow Water (AtOW) and cold, fresh Arctic‐origin Overflow Water (ArOW). The former is found predominantly within the East Greenland Current (EGC), while the latter resides in the interior of the Iceland and Greenland Seas. Progressing north to south, the properties of AtOW in the EGC are modified diapycnally during the winter, in contrast to summer when along‐isopycnal mixing dominates. The water column response to a 10‐days cold‐air outbreak was documented using repeat observations. During the event, the northerly winds pushed the freshwater cap of the EGC onshore, and convection modified the water at the seaward edge of the current. Lateral transfer of heat and salt from the core of AtOW in the EGC appears to have influenced some of this water mass transformation. The long‐term evolution of the mixed layers in the interior was investigated using a 1‐D mixing model. This suggests that, under strong atmospheric forcing, the densest component of ArOW can be ventilated in this region. Numerous anti‐cyclonic eddies spawned from the EGC were observed during the winter survey, revealing that these features can play differing roles in modifying/prohibiting the open‐ocean convection.

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“…The setup of the IGP run (Spall et al., 2021) differs in several aspects from the ASR and ERA runs. First, the domain reaches further East and North, thus covering the entire Greenland‐Iceland‐Norwegian Seas area.…”

Section: Methodsmentioning

confidence: 99%

“…For this study, we used a set of three numerical simulations. All simulations are hydrostatic regional ocean-sea ice configurations in the Massachusetts Institute of Technology general circulation model (MITgcm; Marshall et al, 1997), described in detail in previous work and shown to represent the regional ocean properties and dynamics faithfully (Almansi et al, 2017(Almansi et al, , 2020Foukal et al, 2020;Gelderloos et al, 2021;Håvik et al, 2019;Saberi et al, 2020;Spall et al, 2021). The representation of fjords specifically in these simulations has not been evaluated previously, and is part of this manuscript (Sections 3 and 4).…”

Section: Numerical Simulationsmentioning

confidence: 99%

Subinertial Variability in Four Southeast Greenland Fjords in Realistic Numerical Simulations

Gelderloos

Haine

Almansi³

2022

JGR Oceans

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We identified the nature and driving mechanisms of subinertial variability (variability at a time scale of several days) in four fjords in Southeast Greenland, in three high‐resolution numerical simulations. We find two dominant frequency ranges in along‐fjord velocity, volume transport of Atlantic Water, and along‐fjord heat transport: one around 2–4 days and one around 10 days. The higher frequency is most prominent in the two smaller fjords (Sermilik Fjord and Kangerdlugssuaq Fjord), while the lower frequency peak dominates in the larger fjords (Scoresby Sund and King Oscar Fjord). The cross‐fjord structure of variability patterns is determined by the fjord's dynamic width, while the vertical structure is determined by the stratification in the fjord. The dominant frequency range is a function of stratification and fjord length, through the travel time of resonant internal Kelvin waves. We find that the subinertial variability is the imprint of Coastal Trapped Waves, which manifest as Rossby‐type waves on the continental shelf and as internal Kelvin‐type waves inside the fjords. Between 50% and 80% of the variability in the fjord is directly forced by Coastal Trapped Waves propagating in from the shelf, with an additional role played by alongshore wind forcing on the shelf.

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Lateral redistribution of heat and salt in the Nordic Seas

Cited by 11 publications

References 61 publications

AMOC Recent and Future Trends: A Crucial Role for Oceanic Resolution and Greenland Melting?

AMOC Recent and Future Trends: A Crucial Role for Oceanic Resolution and Greenland Melting?

Wintertime Water Mass Transformation in the Western Iceland and Greenland Seas

Subinertial Variability in Four Southeast Greenland Fjords in Realistic Numerical Simulations

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