Tracing Glacial Meltwater From the Greenland Ice Sheet to the Ocean Using Gliders

Hendry, Katharine R.; Briggs, Nathan; Henson, Stephanie A.; Opher, Jacob; Brearley, J. Alexander; Meredith, Michael P.; Leng, Melanie J.; Meire, Lorenz

doi:10.1029/2021jc017274

Cited by 6 publications

(5 citation statements)

References 82 publications

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“…The eddy kinetic energy, a measure of the eddy activity, is indeed very high off the southwestern coast of Greenland (Figure 10). Such a process has also been recently nicely illustrated in observational data, by following GrIS meltwater with gliders using fluorescing dissolved organic matter, a proxy of those meltwaters (Hendry et al, 2021). The nature of eddies in the Labrador Sea is however complex as illustrated in Rieck et al (2019), with different types of eddies, generated either by baroclinic or barotropic instabilities and strongly dependent on bathymetry characteristics.…”

Section: Discussionmentioning

confidence: 91%

“…The authors argued that this could be related to the freshening trend in the Labrador Sea possibly due to the increase of GrIS melting. A possible impact of ocean eddies is linked to their role in spreading of the surface freshwater input from the GrIS into the interior Labrador Sea as was suggested by, e.g., Yang et al (2016) and more recently from glider observations by Hendry et al (2021).…”

Section: Fresh News From High Resolution Model Simulationsmentioning

confidence: 89%

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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: 91%

Section: Fresh News From High Resolution Model Simulationsmentioning

confidence: 89%

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

et al. 2022

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“…Bioavailable glacial DOM is consistent with findings on Arctic land terminating glacier systems (Fellman et al., 2010; Kellerman et al., 2020; Pain et al., 2020), but this is the first demonstration of labile DOM delivery from a marine‐terminating glacier. Distinctive DOM fluorescence in glacially modified coastal waters around southwestern Greenland has also been reported recently and may be linked to glacier DOM delivery across boundary currents, although the ultimate source is unclear (Hendry et al., 2021). It is interesting to speculate how large the impact of glacial DOM might be versus other local sources (e.g., primary production, upwelling, and nonglacial terrestrial inputs) and how rapidly each may be consumed by heterotrophic organisms in the marine environment, given the low export flux may be balanced by high bioavailability.…”

Section: Figurementioning

confidence: 72%

Trickle and Treat? The Critical Role of Marine‐Terminating Glaciers as Icy Macronutrient Pumps in Polar Regions

Hawkings

2021

JGR Biogeosciences

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The delivery of the macronutrients carbon (C), nitrogen (N), phosphorus (P), and silicon (Si) to the euphotic zone of the coastal ocean represents one of the most important biogeochemical processes on Earth (Jickells, 1998;Moore et al., 2013). Macronutrients sustain microbial primary and secondary production, which are vital components of the global carbon cycle (De La Rocha & Passow, 2014). These microscopic organisms form the base of the marine food web and therefore dictate the structure of the marine ecosystem, including the vitality of environmentally and economically important fisheries (Chassot et al., 2010). Both land inputs and the hydrodynamics of coastal waters play critical roles in replenishing surface waters with nutrients for growth (Tseng et al., 2014). The main sources of nutrients transported from land to ocean are rivers (Statham, 2012), groundwater (Santos et al., 2021, and atmospheric aerosols/dust (Jickells et al., 2016). Upwelling waters at continental and island margins bring nutrient-rich deep water to the ocean surface (

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“…These observational results indicate that FOM vis measurement by an in situ sensor can be a useful method for tracing the lateral transport of anoxic sediment-derived nutrients from coastal regions to offshore oceans. In situ sensors for FOM vis observation can be installed on ship-based CTD systems (Coble et al, 1998;Shigemitsu et al, 2020;Stedmon et al, 2021;Yamashita et al, 2015Yamashita et al, , 2019 and also on other oceanographic observational tools, such as underwater pumping systems (Chen & Gardner, 2004;Coble et al, 1998), biogeochemical-argo floats (Organelli & Claustre, 2019;Xing et al, 2012Xing et al, , 2014, gliders (Hendry et al, 2021;Loginova et al, 2016), and buoys (Qu et al, 2020). The combination of FOM vis observations by using in situ sensors, analysis of a tracer for sediment-water column exchange, and nutrient analyses can be used to quantitatively assess transport of sediment-derived nutrients from coastal regions to offshore oceans with high spatiotemporal resolution.…”

Section: Discussionmentioning

confidence: 99%

Tracing Sediment‐Affected Water Masses From Coastal Areas to Offshore Oceans Using In Situ Sensing of Fluorescent Organic Matter

Yamashita,

Takekuma,

Tajiri

et al. 2024

JGR Oceans

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The lateral transport of nutrient‐rich water masses from coastal areas to offshore areas is an important factor controlling the primary production of phytoplankton in offshore regions. If the coastal low‐salinity waters have high nutrient levels, lateral transport can be traced via salinity observations. However, if high level of nutrients in the waters are not coupled with low salinity, for example, input from coastal sediments, water transport cannot be traced via salinity observations. In this study, visible fluorescent organic matter (FOMvis) was monitored by an in situ sensor as a tracer for sediment‐affected water masses from coastal areas. The FOMvis distribution in the upper 500 m water layer in offshore Japan along the 143°E transect was generally controlled by the distributions of subtropical water (i.e., Kuroshio water and Tsugaru warm current water) and subarctic water (i.e., Oyashio water). However, anomalously high levels of FOMvis were observed at depths of 20–60 m at an observational station, which could not be explained by physical mixing. This likely originated from the lateral transport of water masses from coastal areas. In and around Sendai Bay, where observations were carried out as an example of the Japanese coast, high levels of FOMvis were observed, accompanied by negative N*, an indicator of denitrification, and phosphate and silicic acid inputs from anoxic sediments. These observational results imply that FOMvis observation via in situ sensors can be useful for tracing the input of nutrient‐rich sediment‐affected water masses from coastal areas to offshore oceans.

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Tracing Glacial Meltwater From the Greenland Ice Sheet to the Ocean Using Gliders

Cited by 6 publications

References 82 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?

Trickle and Treat? The Critical Role of Marine‐Terminating Glaciers as Icy Macronutrient Pumps in Polar Regions

Tracing Sediment‐Affected Water Masses From Coastal Areas to Offshore Oceans Using In Situ Sensing of Fluorescent Organic Matter

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