@article {273,
	title = {Air-Sea Interactions and Water Mass Transformation During a Katabatic Storm in the Irminger Sea},
	journal = {Journal of Geophysical Research: Oceans},
	volume = {127},
	year = {2022},
	month = {2022///},
	pages = {e2021JC018075},
	abstract = {We use a global 5-km resolution model to analyze the air-sea interactions during a katabatic storm in the Irminger Sea originating from the Ammassalik valleys. Katabatic storms have not yet been resolved in global climate models, raising the question of whether and how they modify water masses in the Irminger Sea. Our results show that dense water forms along the boundary current and on the shelf during the katabatic storm due to the heat loss caused by the high wind speeds and the strong temperature contrast. The dense water contributes to the lightest upper North Atlantic Deep Water as upper Irminger Sea Intermediate Water and thus to the lower limb of the Atlantic Meridional Overturning Circulation (AMOC). The katabatic storm triggers a polar low, which in turn amplifies the near-surface wind speed due to the superimposed pressure gradient, in addition to acceleration from a breaking mountain wave. Overall, katabatic storms account for up to 25\% of the total heat loss (20 January 2020 to 30 September 2021) over the Irminger shelf of the Ammassalik area. Resolving katabatic storms in global models is therefore important for the formation of dense water in the western boundary current of the Irminger Sea, which is relevant to the AMOC, and for the large-scale atmospheric circulation by triggering polar lows.},
	keywords = {air-sea interaction, DYAMOND Winter, ICON, katabatic winds, storm-resolving global climate model, water mass transformation},
	isbn = {2169-9291},
	doi = {10.1029/2021JC018075},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021JC018075},
	author = {Gutjahr, O. and Jungclaus, J. H. and Br{\"u}ggemann, N. and Haak, H. and Marotzke, J.}
}
@article {269,
	title = {Arrival of New Great Salinity Anomaly Weakens Convection in the Irminger Sea},
	journal = {Geophysical Research Letters},
	volume = {49},
	year = {2022},
	month = {2022/06/09/},
	pages = {e2022GL098857},
	abstract = {The Subpolar North Atlantic is prone to recurrent extreme freshening events called Great Salinity Anomalies (GSAs). Here, we combine hydrographic ocean analyses and moored observations to document the arrival, spreading, and impacts of the most recent GSA in the Irminger Sea. This GSA is associated with a rapid freshening of the upper Irminger Sea between 2015 and 2020, culminating in annually averaged salinities as low as the freshest years of the 1990s and possibly since 1960. Upon the GSA propagation into the Irminger Sea over the Reykjanes Ridge, the boundary currents rapidly advected its signal around the basin within months while fresher waters slowly spread and accumulated into the interior. The anomalies in the interior freshened waters produced by deep convection during the 2017{\textendash}2018 winter and actively contributed to the suppression of deep convection in the following two winters.},
	keywords = {13 Climate Action},
	isbn = {0094-8276},
	doi = {10.1029/2022GL098857},
	author = {Bil{\'o}, T.C. and Straneo, F. and Holte, J. and Le Bras, I. A.-A.}
}
@article {270,
	title = {Historical Reconstruction of Subpolar North Atlantic Overturning and Its Relationship to Density},
	journal = {Journal of Geophysical Research: Oceans},
	volume = {127},
	year = {2022},
	month = {2022/06//},
	pages = {e2021JC017732},
	abstract = {The connections between the overturning of the subpolar North Atlantic and regional density changes are assessed on interannual and decadal timescales using historical, data-based reconstructions of the overturning over the last 60 years and forward model integrations with buoyancy and wind forcing. The data-based reconstructions reveal a dominant eastern basin contribution to the subpolar overturning in density space and changes in the overturning reaching {\textpm}2.5 Sv, which are both in accord with the Overturning in the Subpolar North Atlantic Program (OSNAP). The zonally integrated geostrophic velocity across the basin is connected to boundary contrasts in Montgomery potential in density space. The overturning for the eastern side of the basin is strongly correlated with density changes in the Irminger and Labrador Seas, while the overturning for the western side is correlated with boundary density changes in the Labrador Sea. These boundary density signals are a consequence of local atmospheric forcing and transport of upstream density changes. In forward model experiments, a localized density increase over the Irminger Sea increases the overturning over both sides of the basin due to dense waters spreading to the Labrador Sea. Conversely, a localized density increase over the Labrador Sea only increases the overturning for the western basin and instead eventually decreases the overturning for the eastern basin. Labrador Sea density provides a useful overturning metric by its direct control of the overturning over the western side and lower latitudes of the subpolar basin.},
	isbn = {2169-9275},
	doi = {10.1029/2021JC017732},
	author = {Roussenov, Vassil M. and Williams, Richard G. and Lozier, M. Susan and Holliday, N. Penny and Smith, Doug M.}
}
@article {284,
	title = {Long-Term Freezing Temperatures Frequency Change Effect on Wind Energy Gain (Eurasia and North America, 1950{\textendash}2019)},
	journal = {Sustainability},
	volume = {14},
	year = {2022},
	month = {2022/01//},
	pages = {5630},
	abstract = {The persistent freezing conditions in cold regions are the cause of ice accretion on mechanical and instrumental elements of wind turbines. Consequently, remarkable Annual Energy Production (AEP) losses are prone to occur in those wind farms. Following global expansion of wind energy, these areas have had increased study interest in recent years. The goal of these studies is an improved characterisation of the site for the installation of turbines, which could prevent unexpected high AEP losses due to ice accretion on them. In this context, this paper provides an estimation of the freezing temperatures frequency (FTF) at 100 m over latitudes and evaluates the changes during the last 70 years. To that end, hourly surface temperature data (2 m above surface) from the ERA5 reanalysis is used in the [50o N, 75o N] latitudinal belt for the period 1950{\textendash}2019. The obtained results show an average reduction of FTF hours of 72.5 h/decade for all the domain, reaching a maximum decrease of 621 h/decade on the southeast coast of Greenland and a 60\% annual reduction at a specific location in Scandinavia. In terms of AEP a maximum gain of more than 26\% would be projected, as categorised by the the International Energy Agency.},
	keywords = {annual energy production, applied mathematics, ERA5, global warming, ice accretion, Temperature, wind energy potential},
	isbn = {2071-1050},
	doi = {10.3390/su14095630},
	url = {https://www.mdpi.com/2071-1050/14/9/5630},
	author = {Aizpurua-Etxezarreta, Maddi and Carreno-Madinabeitia, Sheila and Ulazia, Alain and S{\'a}enz, Jon and Saenz-Aguirre, Aitor}
}
@article {272,
	title = {The Role of the Irminger Current in the Irminger Sea Northward Transport Variability},
	journal = {Journal of Geophysical Research: Oceans},
	volume = {127},
	year = {2022},
	month = {2022///},
	pages = {e2021JC018188},
	abstract = {The Irminger Current (IC) on the western flank of the Reykjanes Ridge is an important contributor to the northward transport in the Atlantic Meridional Overturning Circulation. Here, we combine 28 years of Copernicus Marine Environment Monitoring Service (CMEMS) ocean reanalysis data with 6 years of mooring data to investigate variability in volume transport of the IC. We found a mean volume transport for the IC of 11.6 Sv between 1993 and 2020 revealing the dominance of the IC in the total Irminger Sea northward volume transport (20.3 Sv). We found a significant decrease (-3.7 Sv) in volume transport of the IC until 2011 followed by a steeper (but shorter, leading to +2.7 Sv) increase until 2020. These changes across the Irminger Sea section are dominated by the IC, which in turn are driven by changes in the density gradient across the Irminger Sea related to convection. On decadal and interannual time scales the IC volume transport is well correlated with the decrease in the sea surface height difference over the basin. In 2019, a temporary intensification of the western IC core led to an exceptionally strong volume transport of the IC with 20 Sv. This was caused by density changes within the IC boundaries due to the presence of mesoscale eddies. Thus, IC transport variability is a superposition of basin-wide to local processes that influence the velocity field on different time scales.},
	keywords = {AMOC, convection, Irminger Current, Irminger Sea, OSNAP},
	isbn = {2169-9291},
	doi = {10.1029/2021JC018188},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2021JC018188},
	author = {Fried, Nora and de Jong, M. Femke}
}
@article {RN211,
	title = {More than skin deep: sea surface temperature as a means of inferring Atlantic Water variability on the southeast Greenland continental shelf near Helheim Glacier},
	journal = {Journal of Geophysical Research - Oceans},
	year = {2021},
	type = {Journal Article},
	abstract = {Outlet glaciers account for almost half of the Greenland Ice Sheet{\textquoteright}s mass loss since 1990. Warming subsurface Atlantic Water (AW) has been implicated in much of that loss, particularly along Greenland{\textquoteright}s southeastern coast. However, oceanographic observations are sparse prior to the last decade, making it difficult to diagnose changes in AW properties reaching the glaciers. Here, we investigate the use of sea surface temperatures (SST) to quantify ocean temperature variability on the continental shelf near Sermilik Fjord and Helheim Glacier. We find that after removing the short-term, atmospheric-driven variability in non-winter months, regional SSTs provide a reliable upper ocean temperature record. In the trough region near Sermilik Fjord, the adjusted SSTs correlate well with moored ocean measurements of the water entering the fjord at depth and driving glacier melting. Using this relationship, we reconstruct the AW variability on the shelf dating back to 2000, eight years before the first mooring deployments. Seasonally, AW reaches close to the fjord{\textquoteright}s mouth in fall and winter and further offshore in spring. Interannually, the AW temperatures in the trough do not always track properties in the source waters of the Irminger Current. Instead, the properties of the waters found at the fjord mouth depend on both variations in the source AW and, also, in the Polar Water that flows into the region from the Arctic Ocean. Satellite-derived SSTs, although dependent on local oceanography, have the potential to improve understanding around previously unanswered glacier-ocean questions in areas surrounding Greenland and Antarctica.},
	doi = {10.1029/2020jc016509},
	url = {https://app.dimensions.ai/details/publication/pub.1136983754},
	author = {Snow, T. and Straneo, F. and Holte, J. and Grigsby, S. and Abdalati, W. and Scambos, T.}
}
@article {RN246,
	title = {Subpolar North Atlantic western boundary density anomalies and the Meridional Overturning Circulation},
	journal = {Nature Communications},
	volume = {12},
	number = {1},
	year = {2021},
	pages = {3002},
	type = {Journal Article},
	abstract = {Changes in the Atlantic Meridional Overturning Circulation, which have the potential to drive societally-important climate impacts, have traditionally been linked to the strength of deep water formation in the subpolar North Atlantic. Yet there is neither clear observational evidence nor agreement among models about how changes in deep water formation influence overturning. Here, we use data from a trans-basin mooring array (OSNAP{\textemdash}Overturning in the Subpolar North Atlantic Program) to show that winter convection during 2014{\textendash}2018 in the interior basin had minimal impact on density changes in the deep western boundary currents in the subpolar basins. Contrary to previous modeling studies, we find no discernable relationship between western boundary changes and subpolar overturning variability over the observational time scales. Our results require a reconsideration of the notion of deep western boundary changes representing overturning characteristics, with implications for constraining the source of overturning variability within and downstream of the subpolar region.},
	doi = {10.1038/s41467-021-23350-2},
	url = {https://app.dimensions.ai/details/publication/pub.1138293382 https://www.nature.com/articles/s41467-021-23350-2.pdf},
	author = {Li, F. and Lozier, M. S. and Bacon, S. and Bower, A. S. and Cunningham, S. A. and de Jong, M. F. and deYoung, B. and Fraser, N. and Fried, N. and Han, G. and Holliday, N. P. and Holte, J. and Houpert, L. and Inall, M. E. and Johns, W. E. and Jones, S. and Johnson, C. and Karstensen, J. and Le Bras, I. A. and Lherminier, P. and Lin, X. and Mercier, H. and Oltmanns, M. and Pacini, A. and Petit, T. and Pickart, R. S. and Rayner, D. and Straneo, F. and Thierry, V. and Visbeck, M. and Yashayaev, I. and Zhou, C.}
}
@article {RN155,
	title = {Rapid Export of Waters Formed by Convection Near the Irminger Sea{\textquoteright}s Western Boundary},
	journal = {Geophysical Research Letters},
	volume = {47},
	number = {3},
	year = {2020},
	type = {Journal Article},
	abstract = {The standard view of the overturning circulation emphasizes the role of convection, yet for waters to contribute to overturning, they must not only be transformed to higher densities but also exported equatorward. From novel mooring observations in the Irminger Sea (2014{\textendash}2016), we describe two water masses that are formed by convection and show that they have different rates of export in the western boundary current. Upper Irminger Sea Intermediate Water appears to form near the boundary current and is exported rapidly within 3 months of its formation. Deep Irminger Sea Intermediate Water forms in the basin interior and is exported on longer time scales. The subduction of these waters into the boundary current is consistent with an eddy transport mechanism. Our results suggest that light intermediate waters can contribute to overturning as much as waters formed by deeper convection and that the export time scales of both project onto overturning variability.},
	issn = {0094-8276},
	doi = {10.1029/2019GL085989},
	author = {Le Bras, I. A. A. and Straneo, F. and Holte, J. and de Jong, M. F. and Holliday, N. P.}
}
@article {RN149,
	title = {Sustainable Observations of the AMOC: Methodology and Technology},
	journal = {Reviews of Geophysics},
	volume = {58},
	number = {1},
	year = {2020},
	pages = {e2019RG000654},
	type = {Journal Article},
	abstract = {The Atlantic Meridional Overturning Circulation (AMOC) is a key mechanism of heat, freshwater, and carbon redistribution in the climate system. The precept that the AMOC has changed abruptly in the past, notably during and at the end of the last ice age, and that it is {\textquotedblleft}very likely{\textquotedblright} to weaken in the coming century due to anthropogenic climate change is a key motivation for sustained observations of the AMOC. This paper reviews the methodology and technology used to observe the AMOC and assesses these ideas and systems for accuracy, shortcomings, potential improvements, and sustainability. We review hydrographic techniques and look at how these traditional techniques can meet modern requirements. Transport mooring arrays (TMAs) provide the {\textquotedblleft}gold standard{\textquotedblright} for sustained AMOC observing, utilizing dynamic height, current meter, and other instrumentation and techniques to produce continuous observations of the AMOC. We consider the principle of these systems and how they can be sustained and improved into the future. Techniques utilizing indirect measurements, such as satellite altimetry, coupled with in situ measurements, such as the Argo float array, are also discussed. Existing technologies that perhaps have not been fully exploited for estimating AMOC are reviewed and considered for this purpose. Technology is constantly evolving, and we look to the future of technology and how it can be deployed for sustained and expanded AMOC measurements. Finally, all of these methodologies and technologies are considered with a view to a sustained and sustainable future for AMOC observation.},
	issn = {8755-1209},
	doi = {10.1029/2019RG000654},
	url = {https://doi.org/10.1029/2019RG000654},
	author = {McCarthy, G. D. and Brown, P. J. and Flagg, C. N. and Goni, G. and Houpert, L. and Hughes, C. W. and Hummels, R. and Inall, M. and Jochumsen, K. and Larsen, K. M. H. and Lherminier, P. and Meinen, C. S. and Moat, B. I. and Rayner, D. and Rhein, M. and Roessler, A. and Schmid, C. and Smeed, D. A.}
}
@article {RN198,
	title = {Year-Round Measurements of the Irminger Current: Variability of a Two-Core Current System Observed in 2014{\textendash}2016},
	journal = {Journal of Geophysical Research - Oceans},
	volume = {125},
	number = {10},
	year = {2020},
	type = {Journal Article},
	abstract = {The Irminger Current (IC), flowing northeastward along the western flank of the Reykjanes Ridge, is an important component in the overturning of the North Atlantic subpolar gyre. A 2-year (2014{\textendash}2016) time series from moored observations shows that the IC consists of two highly variable current cores. A subsampling experiment, using an ocean reanalysis, showed that this current{\textquoteright}s variability is adequately captured by the array. The two current cores contribute nearly equally to the mean volume transport. The total 2-year mean transport was found to be 10.6 Sv with a standard deviation of daily (monthly) values of 9.2 Sv (4.4 Sv) and a standard error of 1.4 Sv. Mean heat and freshwater transport were 0.21 PW and -22.5 mSv, respectively (Sref = 34.92). The volume transport is strongest in spring, and the average over the first year (8.6 Sv) was lower than that of the second year (12.4 Sv), coinciding with an increase in the density gradient over the array in the second year. The variability of the total transport is dominated by variations in the western core, while the warmer, saltier eastern core contributes more to the heat and (negative) freshwater transport. During the two observed winters, which were marked by exceptional deep convection in the central Irminger Sea, mixed layer deepening down to 400 m depth and outcropping of the 27.7 kg m3 isopycnal were observed within the IC.},
	doi = {10.1029/2020jc016193},
	url = {https://app.dimensions.ai/details/publication/pub.1131253742 https://agupubs.onlinelibrary.wiley.com/doi/pdfdirect/10.1029/2020JC016193},
	author = {Jong, M. F. and Steur, L. and Fried, N. and Bol, R. and Kritsotalakis, S.}
}
@article {RN109,
	title = {Air-Sea Fluxes With a Focus on Heat and Momentum},
	journal = {Frontiers in Marine Science},
	volume = {6},
	year = {2019},
	pages = {430},
	type = {Journal Article},
	abstract = {Turbulent and radiative exchanges of heat between the ocean and atmosphere (hereafter heat fluxes), ocean surface wind stress, and state variables used to estimate them, are Essential Ocean Variables (EOVs) and Essential Climate Variables (ECVs) influencing weather and climate. This paper describes an observational strategy for producing 3-hourly, 25-km (and an aspirational goal of hourly at 10-km) heat flux and wind stress fields over the global, ice-free ocean with breakthrough 1-day random uncertainty of 15 W m{\textendash}2 and a bias of less than 5 W m{\textendash}2. At present this accuracy target is met only for OceanSITES reference station moorings and research vessels (RVs) that follow best practices. To meet these targets globally, in the next decade, satellite-based observations must be optimized for boundary layer measurements of air temperature, humidity, sea surface temperature, and ocean wind stress. In order to tune and validate these satellite measurements, a complementary global in situ flux array, built around an expanded OceanSITES network of time series reference station moorings, is also needed. The array would include 500{\textendash}1000 measurement platforms, including autonomous surface vehicles, moored and drifting buoys, RVs, the existing OceanSITES network of 22 flux sites, and new OceanSITES expanded in 19 key regions. This array would be globally distributed, with 1{\textendash}3 measurement platforms in each nominal 10{\textdegree} by 10{\textdegree} box. These improved moisture and temperature profiles and surface data, if assimilated into Numerical Weather Prediction (NWP) models, would lead to better representation of cloud formation processes, improving state variables and surface radiative and turbulent fluxes from these models. The in situ flux array provides globally distributed measurements and metrics for satellite algorithm development, product validation, and for improving satellite-based, NWP and blended flux products. In addition, some of these flux platforms will also measure direct turbulent fluxes, which can be used to improve algorithms for computation of air-sea exchange of heat and momentum in flux products and models. With these improved air-sea fluxes, the ocean{\textquoteright}s influence on the atmosphere will be better quantified and lead to improved long-term weather forecasts, seasonal-interannual-decadal climate predictions, and regional climate projections.},
	keywords = {air-sea heat flux, autonomous surface vehicle, ICOADS, latent heat flux, ocean wind stress, OceanSITES, satellite-based ocean monitoring system, surface radiation},
	issn = {2296-7745},
	doi = {10.3389/fmars.2019.00430},
	url = {https://www.frontiersin.org/article/10.3389/fmars.2019.00430},
	author = {Cronin, Meghan F. and Gentemann, Chelle L. and Edson, James and Ueki, Iwao and Bourassa, Mark and Brown, Shannon and Clayson, Carol Anne and Fairall, Chris W. and Farrar, J. Thomas and Gille, Sarah T. and Gulev, Sergey and Josey, Simon A. and Kato, Seiji and Katsumata, Masaki and Kent, Elizabeth and Krug, Marjolaine and Minnett, Peter J. and Parfitt, Rhys and Pinker, Rachel T. and Stackhouse, Paul W. and Swart, Sebastiaan and Tomita, Hiroyuki and Vandemark, Douglas and Weller, A. Robert and Yoneyama, Kunio and Yu, Lisan and Zhang, Dongxiao}
}
@article {RN63,
	title = {Extreme Variability in Irminger Sea Winter Heat Loss Revealed by Ocean Observatories Initiative Mooring and the ERA5 Reanalysis},
	journal = {Geophysical Research Letters},
	volume = {46},
	number = {1},
	year = {2019},
	pages = {293-302},
	type = {Journal Article},
	abstract = {Ground-breaking measurements from the ocean observatories initiative Irminger Sea surface mooring (60{\textdegree}N, 39{\textdegree}30'W) are presented that provide the first in situ characterization of multiwinter surface heat exchange at a high latitude North Atlantic site. They reveal strong variability (December 2014 net heat loss nearly 50\% greater than December 2015) due primarily to variations in frequency of intense short timescale (1{\textendash}3 days) forcing. Combining the observations with the new high resolution European Centre for Medium Range Weather Forecasts Reanalysis 5 (ERA5) atmospheric reanalysis, the main source of multiwinter variability is shown to be changes in the frequency of Greenland tip jets (present on 15 days in December 2014 and 3 days in December 2015) that can result in hourly mean heat loss exceeding 800 W/m2. Furthermore, a new picture for atmospheric mode influence on Irminger Sea heat loss is developed whereby strongly positive North Atlantic Oscillation conditions favor increased losses only when not outweighed by the East Atlantic Pattern.

},
	issn = {0094-8276},
	doi = {10.1029/2018GL080956},
	url = {https://doi.org/10.1029/2018GL080956},
	author = {Josey, S. A. and de Jong, M. F. and Oltmanns, M. and Moore, G. K. and Weller, R. A.}
}
@article {RN108,
	title = {Integrated Observations of Global Surface Winds, Currents, and Waves: Requirements and Challenges for the Next Decade},
	journal = {Frontiers in Marine Science},
	volume = {6},
	year = {2019},
	pages = {425},
	type = {Journal Article},
	abstract = {Ocean surface winds, currents, and waves play a crucial role in exchanges of momentum, energy, heat, freshwater, gases, and other tracers between the ocean, atmosphere, and ice. Despite surface waves being strongly coupled to the upper ocean circulation and the overlying atmosphere, efforts to improve ocean, atmospheric, and wave observations and models have evolved somewhat independently. From an observational point of view, community efforts to bridge this gap have led to proposals for satellite Doppler oceanography mission concepts, which could provide unprecedented measurements of absolute surface velocity and directional wave spectrum at global scales. This paper reviews the present state of observations of surface winds, currents, and waves, and it outlines observational gaps that limit our current understanding of coupled processes that happen at the air-sea-ice interface. A significant challenge for the coming decade of wind, current, and wave observations will come in combining and interpreting measurements from (a) wave-buoys and high-frequency radars in coastal regions, (b) surface drifters and wave-enabled drifters in the open-ocean, marginal ice zones, and wave-current interaction {\textquotedblleft}hot-spots,{\textquotedblright} and (c) simultaneous measurements of absolute surface currents, ocean surface wind vector, and directional wave spectrum from Doppler satellite sensors.},
	keywords = {absolute surface velocity, air-sea interactions, Doppler oceanography from space, ocean surface winds, surface waves},
	issn = {2296-7745},
	doi = {10.3389/fmars.2019.00425},
	url = {https://www.frontiersin.org/article/10.3389/fmars.2019.00425},
	author = {Villas B{\^o}as, Ana B. and Ardhuin, Fabrice and Ayet, Alex and Bourassa, Mark A. and Brandt, Peter and Chapron, Betrand and Cornuelle, Bruce D. and Farrar, J. T. and Fewings, Melanie R. and Fox-Kemper, Baylor and Gille, Sarah T. and Gommenginger, Christine and Heimbach, Patrick and Hell, Momme C. and Li, Qing and Mazloff, Matthew R. and Merrifield, Sophia T. and Mouche, Alexis and Rio, Marie H. and Rodriguez, Ernesto and Shutler, Jamie D. and Subramanian, Aneesh C. and Terrill, Eric J. and Tsamados, Michel and Ubelmann, Clement and van Sebille, Erik}
}
@article {RN71,
	title = {A sea change in our view of overturning in the subpolar North Atlantic},
	journal = {Science},
	volume = {363},
	number = {6426},
	year = {2019},
	pages = {516},
	type = {Journal Article},
	abstract = {To provide an observational basis for the Intergovernmental Panel on Climate Change projections of a slowing Atlantic meridional overturning circulation (MOC) in the 21st century, the Overturning in the Subpolar North Atlantic Program (OSNAP) observing system was launched in the summer of 2014. The first 21-month record reveals a highly variable overturning circulation responsible for the majority of the heat and freshwater transport across the OSNAP line. In a departure from the prevailing view that changes in deep water formation in the Labrador Sea dominate MOC variability, these results suggest that the conversion of warm, salty, shallow Atlantic waters into colder, fresher, deep waters that move southward in the Irminger and Iceland basins is largely responsible for overturning and its variability in the subpolar basin.},
	doi = {10.1126/science.aau6592},
	url = {http://science.sciencemag.org/content/363/6426/516.abstract},
	author = {Lozier, M. S. and Li, F. and Bacon, S. and Bahr, F. and Bower, A. S. and Cunningham, S. A. and de Jong, M. F. and de Steur, L. and deYoung, B. and Fischer, J. and Gary, S. F. and Greenan, B. J. W. and Holliday, N. P. and Houk, A. and Houpert, L. and Inall, M. E. and Johns, W. E. and Johnson, H. L. and Johnson, C. and Karstensen, J. and Koman, G. and Le Bras, I. A. and Lin, X. and Mackay, N. and Marshall, D. P. and Mercier, H. and Oltmanns, M. and Pickart, R. S. and Ramsey, A. L. and Rayner, D. and Straneo, F. and Thierry, V. and Torres, D. J. and Williams, R. G. and Wilson, C. and Yang, J. and Yashayaev, I. and Zhao, J.}
}
@article {RN99,
	title = {Transport Variability of the Irminger Sea Deep Western Boundary Current From a Mooring Array},
	journal = {Journal of Geophysical Research-Oceans},
	volume = {124},
	number = {5},
	year = {2019},
	pages = {3246-3278},
	type = {Journal Article},
	abstract = {The Deep Western Boundary Current in the subpolar North Atlantic is the lower limb of the Atlantic Meridional Overturning Circulation and a key component of the global climate system. Here, a mooring array deployed at 60{\textdegree}N in the Irminger Sea, between 2014 and 2016, provides the longest continuous record of total Deep Western Boundary Current volume transport at this latitude. The 1.8-year averaged transport of water denser than σθ = 27.8 kg/m3 was -10.8 {\textpm} 4.9 Sv (mean {\textpm} 1 std; 1 Sv = 106 m3/s). Of this total, we find -4.1 {\textpm} 1.4 Sv within the densest layer (σθ > 27.88 kg/m3) that originated from the Denmark Strait Overflow. The lighter North East Atlantic Deep Water layer (σθ = 27.8{\textendash}27.88 kg/m3) carries -6.5 {\textpm} 7.7 Sv. The variability in transport ranges between 2 and 65 days. There is a distinct shift from high to low frequency with distance from the East Greenland slope. High-frequency fluctuations (2{\textendash}8 days) close to the continental slope are likely associated with topographic Rossby waves and/or cyclonic eddies. Here, perturbations in layer thickness make a significant (20{\textendash}60\%) contribution to transport variability. In deeper water, toward the center of the Irminger Basin, transport variance at 55 days dominates. Our results suggest that there has been a 1.8 Sv increase in total transport since 2005{\textendash}2006, but this difference can be accounted for by a range of methodological and data limitation biases},
	issn = {2169-9275},
	doi = {10.1029/2018JC014730},
	author = {Hopkins, J. E. and Holliday, N. P. and Rayner, D. and Houpert, L. and Le Bras, I. and Straneo, F. and Wilson, C. and Bacon, S.}
}
@article {RN22,
	title = {Deep Convection in the Irminger Sea Observed with a Dense Mooring Array},
	journal = {Oceanography},
	volume = {31},
	number = {1},
	year = {2018},
	pages = {50-59},
	type = {Journal Article},
	abstract = {Deep convection is a key process in the Atlantic Meridional Overturning Circulation, but because it acts at small scales, it remains poorly resolved by climate models. The occurrence of deep convection depends on weak initial stratification and strong surface buoyancy forcing, conditions that are satisfied in only a few ocean basins. In 2014, one of the Ocean Observatories Initiative (OOI) global arrays was installed close to the Central Irminger Sea (CIS) and the Long-term Ocean Circulation Observations (LOCO) moorings in the central Irminger Sea. These programs{\textquoteright} six moorings are located in the center of an area of deep convection and are distributed within a 50 km radius, thus offering detailed insight into spatial differences during the strong convection events that occurred during the winters of 2014/2015 and 2015/2016. Deep mixed layers, down to approximately 1,600 m, formed during both winters. The properties of the convectively renewed water mass at each mooring converge to a common temperature and salinity before restratification sets in at the end of winter. The largest differences in onset (or timing) of convection and restratification are seen between the northernmost and southernmost moorings. High-resolution atmospheric reanalysis data show there is higher atmospheric forcing at the northernmost mooring due to a more favorable position with respect to the Greenland tip jet. Nevertheless, earlier onset, and more continuous cooling and deepening of mixed layers, occurs at the southernmost mooring, while convection at the northern mooring is frequently interrupted by warm events. We propose that these warm events are associated with eddies and filaments originating from the Irminger Current off the coast of Greenland and that convection further south benefits from cold inflow from the southwest.

},
	issn = {10428275},
	doi = {10.5670/oceanog.2018.109},
	author = {de Jong, M. Femke and Oltmanns, Marilena and Karstensen, Johannes and de Steur, Laura}
}
@article {RN32,
	title = {Detection of climate change-driven trends in phytoplankton phenology},
	journal = {Glob Chang Biol},
	volume = {24},
	number = {1},
	year = {2018},
	pages = {e101-e111},
	type = {Journal Article},
	abstract = {The timing of the annual phytoplankton spring bloom is likely to be altered in response to climate change. Quantifying that response has, however, been limited by the typically coarse temporal resolution (monthly) of global climate models. Here, we use higher resolution model output (maximum 5 days) to investigate how phytoplankton bloom timing changes in response to projected 21st century climate change, and how the temporal resolution of data influences the detection of long-term trends. We find that bloom timing generally shifts later at mid-latitudes and earlier at high and low latitudes by ~5 days per decade to 2100. The spatial patterns of bloom timing are similar in both low (monthly) and high (5 day) resolution data, although initiation dates are later at low resolution. The magnitude of the trends in bloom timing from 2006 to 2100 is very similar at high and low resolution, with the result that the number of years of data needed to detect a trend in phytoplankton phenology is relatively insensitive to data temporal resolution. We also investigate the influence of spatial scales on bloom timing and find that trends are generally more rapidly detectable after spatial averaging of data. Our results suggest that, if pinpointing the start date of the spring bloom is the priority, the highest possible temporal resolution data should be used. However, if the priority is detecting long-term trends in bloom timing, data at a temporal resolution of 20 days are likely to be sufficient. Furthermore, our results suggest that data sources which allow for spatial averaging will promote more rapid trend detection.},
	issn = {1365-2486 (Electronic) 1354-1013 (Linking)},
	doi = {10.1111/gcb.13886},
	url = {https://www.ncbi.nlm.nih.gov/pubmed/28871605},
	author = {Henson, S. A. and Cole, H. S. and Hopkins, J. and Martin, A. P. and Yool, A.}
}
@article {RN86,
	title = {Geostatistical Analysis of Mesoscale Spatial Variability and Error in SeaWiFS and MODIS/Aqua Global Ocean Color Data},
	journal = {Journal of Geophysical Research: Oceans},
	volume = {123},
	number = {1},
	year = {2018},
	pages = {22-39},
	type = {Journal Article},
	abstract = {Mesoscale (10{\textendash}300 km, weeks to months) physical variability strongly modulates the structure and dynamics of planktonic marine ecosystems via both turbulent advection and environmental impacts upon biological rates. Using structure function analysis (geostatistics), we quantify the mesoscale biological signals within global 13 year SeaWiFS (1998{\textendash}2010) and 8 year MODIS/Aqua (2003{\textendash}2010) chlorophyll a ocean color data (Level-3, 9 km resolution). We present geographical distributions, seasonality, and interannual variability of key geostatistical parameters: unresolved variability or noise, resolved variability, and spatial range. Resolved variability is nearly identical for both instruments, indicating that geostatistical techniques isolate a robust measure of biophysical mesoscale variability largely independent of measurement platform. In contrast, unresolved variability in MODIS/Aqua is substantially lower than in SeaWiFS, especially in oligotrophic waters where previous analysis identified a problem for the SeaWiFS instrument likely due to sensor noise characteristics. Both records exhibit a statistically significant relationship between resolved mesoscale variability and the low-pass filtered chlorophyll field horizontal gradient magnitude, consistent with physical stirring acting on large-scale gradient as an important factor supporting observed mesoscale variability. Comparable horizontal length scales for variability are found from tracer-based scaling arguments and geostatistical decorrelation. Regional variations between these length scales may reflect scale dependence of biological mechanisms that also create variability directly at the mesoscale, for example, enhanced net phytoplankton growth in coastal and frontal upwelling and convective mixing regions. Global estimates of mesoscale biophysical variability provide an improved basis for evaluating higher resolution, coupled ecosystem-ocean general circulation models, and data assimilation.},
	issn = {2169-9275},
	doi = {10.1002/2017JC013023},
	url = {https://doi.org/10.1002/2017JC013023},
	author = {Glover, David M. and Doney, Scott C. and Oestreich, William K. and Tullo, Alisdair W.}
}
@article {RN41,
	title = {Increased risk of a shutdown of ocean convection posed by warm North Atlantic summers},
	journal = {Nature Climate Change},
	volume = {8},
	number = {4},
	year = {2018},
	pages = {300-+},
	type = {Journal Article},
	abstract = {A shutdown of ocean convection in the subpolar North Atlantic, triggered by enhanced melting over Greenland, is regarded as a potential transition point into a fundamentally different climate regime1,2,3. Noting that a key uncertainty for future convection resides in the relative importance of melting in summer and atmospheric forcing in winter, we investigate the extent to which summer conditions constrain convection with a comprehensive dataset, including hydrographic records that are over a decade in length from the convection regions. We find that warm and fresh summers, characterized by increased sea surface temperatures, freshwater concentrations and melting, are accompanied by reduced heat and buoyancy losses in winter, which entail a longer persistence of the freshwater near the surface and contribute to delaying convection. By shortening the time span for the convective freshwater export, the identified seasonal dynamics introduce a potentially critical threshold that is crossed when substantial amounts of freshwater from one summer are carried over into the next and accumulate. Warm and fresh summers in the Irminger Sea are followed by particularly short convection periods. We estimate that in the winter 2010{\textendash}2011, after the warmest and freshest Irminger Sea summer on our record, ~40\% of the surface freshwater was retained.

},
	issn = {1758-678x},
	doi = {10.1038/s41558-018-0105-1},
	url = {<Go to ISI>://WOS:000429194600015},
	author = {Oltmanns, M. and Karstensen, J. and Fischer, J.}
}
@article {RN29,
	title = {Mean circulation and EKE distribution in the Labrador Sea Water level of the subpolar North Atlantic},
	journal = {Ocean Science Discussions},
	year = {2018},
	pages = {1-27},
	type = {Journal Article},
	abstract = {A long-term mean flow field for the subpolar North Atlantic region with a horizontal resolution of approximately 25 km is created by gridding Argo-derived velocity vectors using two different topography-following interpolation schemes. The 10-day float displacements in the typical drift depths of 1000 to 1500 m represent the flow in the Labrador Sea Water density range. Both mapping algorithms separate the flow field into potential vorticity (PV) conserving, i.e., topography-following contribution and a deviating part, which we define as the eddy contribution. To verify the significance of the separation, we compare the mean flow and the eddy kinetic energy (EKE), derived from both mapping algorithms, with those obtained from multiyear mooring observations.

The PV-conserving mean flow is characterized by stable boundary currents along all major topographic features including shelf breaks and basin-interior topographic ridges such as the Reykjanes Ridge or the Rockall Plateau. Mid-basin northward advection pathways from the northeastern Labrador Sea into the Irminger Sea and from the Mid-Atlantic Ridge region into the Iceland Basin are well-resolved. An eastward flow is present across the southern boundary of the subpolar gyre near 52o N, the latitude of the Charlie Gibbs Fracture Zone (CGFZ).

The mid-depth EKE field resembles most of the satellite-derived surface EKE field. However, noticeable differences exist along the northward advection pathways in the Irminger Sea and the Iceland Basin, where the deep EKE exceeds the surface EKE field. Further, the ratio between mean flow and the square root of the EKE, the Peclet number, reveals distinct advection-dominated regions as well as basin-interior regimes in which mixing is prevailing.

How to cite. 
Fischer, J., Karstensen, J., Oltmanns, M., and Schmidtko, S.: Mean circulation and EKE distribution in the Labrador Sea Water level of the subpolar North Atlantic, Ocean Sci., 14, 1167{\textendash}1183, https://doi.org/10.5194/os-14-1167-2018, 2018.},
	issn = {1812-0822},
	doi = {10.5194/os-2018-56},
	url = {https://staging-ddpp.dimensions.ai/details/publication/pub.1103986302 https://www.ocean-sci-discuss.net/os-2018-56/os-2018-56.pdf},
	author = {Fischer, J{\"u}rgen and Karstensen, Johannes and Oltmanns, Marilena and Schmidtko, Sunke}
}
@article {RN21,
	title = {The North Atlantic Biological Pump INSIGHTS FROM THE OCEAN OBSERVATORIES INITIATIVE IRMINGER SEA ARRAY},
	journal = {Oceanography},
	volume = {31},
	number = {1},
	year = {2018},
	pages = {42-49},
	type = {Journal Article},
	abstract = {The biological pump plays a key role in the global carbon cycle by transporting photosynthetically fixed organic carbon into the deep ocean, where it can be sequestered from the atmosphere over annual or longer time scales if exported below the winter ventilation depth. In the subpolar North Atlantic, carbon sequestration via the biological pump is influenced by two competing forces: a spring diatom bloom that features large, fast-sinking biogenic particles, and deep winter mixing that requires particles to sink much further than in other ocean regions to escape winter ventilation. We synthesize biogeochemical sensor data from the first two years of operations at the Ocean Observatories Initiative Irminger Sea Array of moorings and gliders (September 2014{\textendash}July 2016), providing the first simultaneous year-round observations of biological carbon cycling processes in both the surface ocean and the seasonal thermocline in this critical but previously undersampled region. These data show significant mixed layer net autotrophy during the spring bloom and significant respiration in the seasonal thermocline during the stratified season (~5.9 mol C m{\textendash}2 remineralized between 200 m and 1,000 m). This respired carbon is subsequently ventilated during winter convective mixing (>1,000 m), a significant reduction in potential carbon sequestration. This highlights the importance of year-round observations to accurately constrain the biological pump in the subpolar North Atlantic, as well as other high-latitude regions that experience deep winter mixing.},
	issn = {1042-8275},
	doi = {10.5670/oceanog.2018.108},
	url = {<Go to ISI>://WOS:000427367300008},
	author = {Palevsky, H. I. and Nicholson, D. P.}
}
@article {RN28,
	title = {A regime-dependent retrieval algorithm for near-surface air temperature and specific humidity from multi-microwave sensors},
	journal = {Remote Sensing of Environment},
	volume = {215},
	year = {2018},
	pages = {199-216},
	type = {Journal Article},
	abstract = {Near-surface specific humidity (qa) and air temperature (Ta) over the global ocean are important meteorological variables, but they cannot be retrieved directly from remote sensing. Many efforts have been made to develop algorithms that derive qa and Ta from multisensor microwave and/or infrared observations using in situ measurements as training datasets. However, uncertainty remains large in the resultant qa and Ta retrievals. In this study, 147 moored surface buoys are used to examine how buoy measured qa and Ta are related to satellite microwave brightness temperature (Tb) on the spatial scale from the warm/humid tropics to the cold/dry high latitudes. It is found that the Tb {\textendash} qa and Tb {\textendash} Ta relations are structured along two distinct, near-linear bands, with the primary band in the warm/humid regime and a secondary (weaker) band in the cold/dry regime. The step-like transition (or separation) between the two regimes occurs at 8{\textendash}10 g kg-1 for qa and 14{\textendash}17 {\textdegree}C for Ta. The evidence suggests that one algorithm may not be sufficient to extract qa and Ta from Tb in all regimes. Therefore, a high-latitude enhancement is added to the global algorithm so that the qa and Ta retrievals in the dry/cold regime can be specifically addressed. The new algorithms are applied to 11 microwave sensors, including SSM/I, SSMIS, and AMSU-A, from 1988 to 2016. Based on the 475,717 buoy collocations during the 29-year period, the retrieved qa and Ta have root-mean-square differences of 0.82 g kg-1 and 0.51 {\textdegree}C, respectively.

},
	keywords = {Microwave passive sensors, Moored surface buoys, Multisensor retrieval, Near-surface air temperature and specific humidity, Retrieval algorithm},
	issn = {00344257},
	doi = {10.1016/j.rse.2018.06.001},
	url = {https://staging-ddpp.dimensions.ai/details/publication/pub.1104605412},
	author = {Yu, Lisan and Jin, Xiangze}
}
@article {RN24,
	title = {Overturning in the Subpolar North Atlantic Program: A New International Ocean Observing System},
	journal = {Bulletin of the American Meteorological Society},
	volume = {98},
	number = {4},
	year = {2017},
	pages = {737-752},
	type = {Journal Article},
	abstract = {For decades oceanographers have understood the Atlantic meridional overturning circulation (AMOC) to be primarily driven by changes in the production of deep-water formation in the subpolar and subarctic North Atlantic. Indeed, current Intergovernmental Panel on Climate Change (IPCC) projections of an AMOC slowdown in the twenty-first century based on climate models are attributed to the inhibition of deep convection in the North Atlantic. However, observational evidence for this linkage has been elusive: there has been no clear demonstration of AMOC variability in response to changes in deep-water formation. The motivation for understanding this linkage is compelling, since the overturning circulation has been shown to sequester heat and anthropogenic carbon in the deep ocean. Furthermore, AMOC variability is expected to impact this sequestration as well as have consequences for regional and global climates through its effect on the poleward transport of warm water. Motivated by the need for a mechanistic understanding of the AMOC, an international community has assembled an observing system, Overturning in the Subpolar North Atlantic Program (OSNAP), to provide a continuous record of the transbasin fluxes of heat, mass, and freshwater, and to link that record to convective activity and water mass transformation at high latitudes. OSNAP, in conjunction with the Rapid Climate Change{\textendash}Meridional Overturning Circulation and Heatflux Array (RAPID{\textendash}MOCHA) at 26{\textdegree}N and other observational elements, will provide a comprehensive measure of the three-dimensional AMOC and an understanding of what drives its variability. The OSNAP observing system was fully deployed in the summer of 2014, and the first OSNAP data products are expected in the fall of 2017.},
	issn = {0003-0007 1520-0477},
	doi = {10.1175/bams-d-16-0057.1},
	url = {https://staging-ddpp.dimensions.ai/details/publication/pub.1038223668 http://darchive.mblwhoilibrary.org/bitstream/1912/9015/1/bams-d-16-0057.1.pdf},
	author = {Susan Lozier, M. and Bacon, Sheldon and Bower, Amy S. and Cunningham, Stuart A. and Femke de Jong, M. and de Steur, Laura and deYoung, Brad and Fischer, J{\"u}rgen and Gary, Stefan F. and Greenan, Blair J. W. and Heimbach, Patrick and Holliday, Naomi P. and Houpert, Lo{\"\i}c and Inall, Mark E. and Johns, William E. and Johnson, Helen L. and Karstensen, Johannes and Li, Feili and Lin, Xiaopei and Mackay, Neill and Marshall, David P. and Mercier, Herl{\'e} and Myers, Paul G. and Pickart, Robert S. and Pillar, Helen R. and Straneo, Fiammetta and Thierry, Virginie and Weller, Robert A. and Williams, Richard G. and Wilson, Chris and Yang, Jiayan and Zhao, Jian and Zika, Jan D.}
}
@article {RN50,
	title = {Strong winter cooling over the Irminger Sea in winter 2014-2015, exceptional deep convection, and the emergence of anomalously low SST},
	journal = {Geophysical Research Letters},
	volume = {43},
	number = {13},
	year = {2016},
	pages = {7106-7113},
	type = {Journal Article},
	abstract = {Deep convection is presumed to be vital for the North Atlantic Meridional Overturning Circulation, even though observational evidence for the link remains inconclusive. Modeling studies have suggested that convection will weaken as a result of enhanced freshwater input. The emergence of anomalously low sea surface temperature in the subpolar North Atlantic has led to speculation that this process is already at work. Here we show that strong atmospheric forcing in the winter of 2014{\textendash}2015, associated with a high North Atlantic Oscillation (NAO) index, produced record mixed layer depths in the Irminger Sea. Local mixing removed the stratification of the upper 1400 m and ventilated the basin to middepths resembling a state similar to the mid-1990s when a positive NAO also prevailed. We show that the strong local atmospheric forcing is predominantly responsible for the negative sea surface temperature anomalies observed in the subpolar North Atlantic in 2015 and that there is no evidence of permanently weakened deep convection.},
	issn = {00948276},
	doi = {10.1002/2016gl069596},
	author = {de Jong, Marieke Femke and de Steur, Laura}
}
