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1. A dataset for multidisciplinary applications: thirteen years of ocean observations in Sermilik Fjord, Southeast Greenland

   https://doi.org/10.5194/essd-17-6025-2025  

   Roth, Aurora; Straneo, Fiamma; Holte, James; Lindeman, Margaret; Mazloff, Matthew (January 2025, Earth System Science Data)

   Abstract. As global atmosphere and ocean temperatures rise and the Greenland Ice Sheet loses mass, the glacial fjords of Kalaallit Nunaat/Greenland play an increasingly critical role in our climate system. Fjords are pathways for freshwater from ice melt to reach the ocean and for deep, warm, nutrient-rich ocean waters to reach marine–terminating glaciers, supporting abundant local ecosystems that Greenlanders rely upon. Research in Greenland fjords has become more interdisciplinary and more observations are being collected in fjords than in previous decades. However, there are few long-term (> 10 years) datasets available for single fjords. Additionally, observations in fjords are often spatially and temporally disjointed, utilize multiple observing tools, and datasets are rarely provided in formats that are easily used across disciplines or audiences. We address this issue by providing standardized, gridded summer season hydrographic sections for Sermilik Fjord in Southeast Greenland, from 2009–2023. Gridded data facilitate the analysis of coherent spatial patterns across the fjord domain, and are a more accessible and intuitive data product compared to discrete profiles. We combined ship-based conductivity, temperature, and depth (CTD) profiles with helicopter-deployed eXpendable CTD (XCTD) profiles from the ice mélange region to create objectively mapped (or optimally interpolated) along-fjord sections of conservative temperature and absolute salinity. From the gridded data, we derived a summer season climatological mean and root mean square deviation, summarizing typical fjord conditions and highlighting regions of variability. This information can be used by model and laboratory studies, biological and ecosystem studies in the fjord, and provides context for interpreting previous work. Additionally, this method can be applied to datasets from other fjords helping to facilitate fjord intercomparison studies. The gridded data and climatological products are available in netCDF format at https://doi.org/10.18739/A28G8FK6D (Roth et al., 2025a). All original profile observations, with unique DOIs for each field campaign, are available through the Sermilik Fjord Hydrography Data Portal (https://arcticdata.io/catalog/portals/sermilik, last access: 7 November 2025) hosted by the Arctic Data Center (Straneo et al., 2025). The code used has also been made available to facilitate continued updates to the Sermilik Fjord gridded section dataset and applications to other fjord systems. 

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2. Low mercury concentrations in a Greenland glacial fjord attributed to oceanic sources

   https://doi.org/10.1038/s43247-024-01474-9  

   Lindeman, M_R; Straneo, F.; Adams, H_M; Nelson, M_J_S; Schartup, A_T (June 2024, Communications Earth & Environment)

   Abstract As the role of the Greenland Ice Sheet in the Arctic mercury (Hg) budget draws scrutiny, it is crucial to understand mercury cycling in glacial fjords, which control exchanges with the ocean. We present full water column measurements of total mercury (THg) and methylmercury (MeHg) in Sermilik Fjord, a large fjord in southeast Greenland fed by multiple marine-terminating glaciers, whose circulation and water mass transformations have been extensively studied. We show that THg (0.23-1.1 pM) and MeHg (0.02-0.17 pM) concentrations are similar to those in nearby coastal waters, while the exported glacially-modified waters are relatively depleted in inorganic mercury (Hg(II)), suggesting that inflowing ocean waters from the continental shelf are the dominant source of mercury species to the fjord. We propose that sediments initially suspended in glacier meltwaters scavenge particle-reactive Hg(II) and are subsequently buried, making the fjord a net sink of oceanic mercury. 

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3. Ilulissat Icefjord Upper‐Layer Circulation Patterns Revealed Through GPS‐Tracked Icebergs

   https://doi.org/10.1029/2023JC020117  

   Baratta, Sydney_J N; Schild, Kristin M; Sutherland, David A (January 2024, Journal of Geophysical Research: Oceans)

   Abstract The Greenland Ice Sheet has undergone rapid mass loss over the last four decades, primarily through solid and liquid discharge at marine‐terminating outlet glaciers. The acceleration of these glaciers is in part due to the increase in temperature of ocean water in contact with the glacier terminus. However, quantifying heat transport to the glacier through fjord circulation can be challenging due to iceberg abundance, which threatens instrument survival and fjord accessibility. Here we utilize iceberg movement to infer upper‐layer fjord circulation, as freely floating icebergs (i.e., outside the mélange region) behave as natural drifters. In the summers of 2014 and 2019, we deployed transmitting GPS units on a total of 13 icebergs in Ilulissat Icefjord, an iceberg‐rich and historically data‐poor fjord in west Greenland, to quantify circulation over the upper 0–250 m of the water column. We find that the direction of upper‐layer fjord circulation is strongly impacted by the timing of tributary meltwater runoff, while the speed of this circulation changes in concert with glacier behavior, which includes increases and decreases in glacier speed and meltwater runoff. During periods of increased meltwater runoff entering from tributary fjords, icebergs at these confluences deviated from their down‐fjord trajectory, even reversing up‐fjord, until the runoff pulse subsided days later. This study demonstrates the utility of iceberg monitoring to constrain upper‐layer fjord circulation, and highlights the importance of including tributary fjords in predictive models of heat transport and fjord circulation. 

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4. Evaluation of Iceberg Calving Models Against Observations From Greenland Outlet Glaciers

   https://doi.org/10.1029/2019JF005444  

   Amaral, Tristan; Bartholomaus, Timothy_C; Enderlin, Ellyn_M (June 2020, Journal of Geophysical Research: Earth Surface)

   Abstract Frontal ablation processes at marine‐terminating glaciers are challenging to observe and difficult to represent in numerical ice flow models, yet play critical roles in modulating ice sheet mass balance. Current ice sheet models typically rely on simple iceberg calving models to prescribe either terminus positions or iceberg calving rates, but the relative accuracies and uncertainties of these calving models remain largely unconstrained at the ice sheet scale. Here, we evaluate six published iceberg calving models against spatially and temporally diverse observations from 50 marine‐terminating outlet glaciers in Greenland. We seek the single model that best reproduces observed conditions across all glaciers, at all observation times, and with low sensitivity to calibration uncertainty. Five of six calving models can produce unbiased estimates of calving position or calving rate at the ice sheet scale. However, time series analysis reveals that, when using a single, optimized model parameter, rate‐predicting calving models frequently yield calving rate errors in excess of 10 m d⁻¹. In comparison, terminus position‐predicting calving models more accurately track observed changes in terminus position (remaining within ~1 km of the observed grounded terminus position). Overall, our results indicate that the crevasse depth calving model provides the best balance of high accuracy and low sensitivity to imperfect parameter calibration. While the crevasse depth model appears unlikely to capture the true controls on crevasse penetration, numerically, it reproduces observed terminus dynamics with high fidelity and should be considered a leading candidate for use in models of the Greenland Ice Sheet. 

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5. New constraints on the last deglaciation of the Cordilleran Ice Sheet in coastal Southeast Alaska

   https://doi.org/10.1017/qua.2020.32  

   Lesnek, Alia J.; Briner, Jason P.; Baichtal, James F.; Lyles, Alex S. (July 2020, Quaternary Research)

   null (Ed.)

   Abstract Understanding marine-terminating ice sheet response to past climate transitions provides valuable long-term context for observations of modern ice sheet change. Here, we reconstruct the last deglaciation of marine-terminating Cordilleran Ice Sheet (CIS) margins in Southeast Alaska and explore potential forcings of western CIS retreat. We combine 27 new cosmogenic 10 Be exposure ages, 13 recently published 10 Be ages, and 25 new 14 C ages from raised marine sediments to constrain CIS recession. Retreat from the outer coast was underway by 17 ka, and the inner fjords and sounds were ice-free by 15 ka. After 15 ka, the western margin of the CIS became primarily land-terminating and alpine glaciers disappeared from the outer coast. Isolated alpine glaciers may have persisted in high inland peaks until the early Holocene. Our results suggest that the most rapid phase of CIS retreat along the Pacific coast occurred between ~17 and 15 ka. This retreat was likely driven by processes operating at the ice-ocean interface, including sea level rise and ocean warming. CIS recession after ~15 ka occurred during a time of climatic amelioration in this region, when both ocean and air temperatures increased. These data highlight the sensitivity of marine-terminating CIS regions to deglacial climate change. 

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