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Abstract Sediment discharged from the Greenland Ice Sheet delivers nutrients to marine ecosystems around Greenland and shapes seafloor habitats. Current estimates of the total sediment flux are constrained by observations from land-terminating glaciers only. Addressing this gap, our study presents a budget derived from observations at 30 marine-margin locations. Analyzing sediment cores from nine glaciated fjords, we assess spatial deposition since 1950. A significant correlation is established between mass accumulation rates, normalized by surface runoff, and distance down-fjord. This enables calculating annual sediment flux at any fjord point based on nearby marine-terminating outlet glacier melt data. Findings reveal a total annual sediment flux of 1.324 + /− 0.79 Gt yr-1 over the period 2010-2020 from all marine-terminating glaciers to the fjords. These estimates are valuable for studies aiming to understand the basal ice sheet conditions and for studies predicting ecosystem changes in Greenland’s fjords and offshore areas as the ice sheet melts and sediment discharge increase. 

This gridded hydrographic data set for Sermilik Fjord was created by objectively mapping (optimally interpolating) discrete hydrographic profile datasets from shipboard Conductivity Temperature Depth (CTD) and helicopter-deployed eXpendable CTDs (XCTDs). These data are all from the summer season (July - September) and cover the years 2009 - 2023 (excluding 2014 and 2020). Grids are standardized to 2 kilometer (km) (horizontal) x 5 meter (m) (depth) resolution grid stretching from 0 km (at Helheim Glacier terminus in 2019) to 106 km away from the terminus following the deepest pathway of bathymetry from the glacier to the shelf (thalweg section). CTD and XCTD profiles were combined to increase along-fjord coverage of the gridded fields. Appropriate gridding parameters and the a priori error were found through a series of manual tests to find a balance between smoothness and hydrographic feature representation (more information in Roth et al. (2025)). The same parameters were used for gridding all variables. Currently the conservative temperature (°C, celsius) and absolute salinity (g kg^-1 (gram per kilogram)) fields, along with their associated mapping relative error, are provided. Other hydrographic variables (eg. dissolved oxygen, nitrate) can be added in the future following the method in Roth et al. (2025) and future surveys of Sermilik Fjord can also be added to increase the time coverage. 

Eighty-one temperature, salinity, dissolved oxygen, turbidity, and fluorescence profiles from Sermilik Fjord and the Southeast Greenland shelf. The temperature, salinity, and dissolved oxygen profiles were collected with a Seabird 25plus conductivity-temperature-depth (CTD) (serial #0251108); the turbidity and fluorescence profiles were collected with a Seabird ECO FLNTU (serial #7748). The profiles were collected during August 2023 from research vessel Tarajoq. The profiles were manually examined and are provided as 1-meter (m) bin averages. The fjord survey was comprised of an along-fjord section and a section spanning the mouth of the fjord. The shelf survey traces the trough that feeds Sermilik. These data were collected as part of a project examining the physical, biogeochemical, and ecological systems of the fjord. The also contributed to a long-term project to monitor Sermilik Fjord to determine what water masses flow into the fjord; in particular, if warm, Atlantic water from the Irminger Sea is able to penetrate into the fjord. Observations have been collected in the fjord since 2008. 

Twelve temperature and salinity profiles from Sermilik Fjord in Southeast Greenland. The profiles were collected using Sippican XCTD-1 eXpendable Conductivity Temperature Depth (XCTD) probes hand deployed from a helicopter. The profiles were collected on July 12, 2023 in the ice mélange of Helheim Glacier and in the northern portion of Sermilik Fjord, including Midgaard Fjord. The profiles were manually examined, quality controlled, and are provided as 2-meter (m) depth bin averaged profiles. These data were collected as part of a long-term project to monitor Sermilik Fjord to determine what water masses flow into and out of the fjord; in particular, if warm, Atlantic water from the Irminger Sea penetrates into the fjord and how freshwater from ice melt is diluted and transported out of the fjord. Observations have been collected in the fjord since 2008. 

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. 

Greenland’s coastal margins are influenced by the confluence of Arctic and Atlantic waters, sea ice, icebergs, and meltwater from the ice sheet. Hundreds of spectacular glacial fjords cut through the coastline and support thriving marine ecosystems and, in some places, adjacent Greenlandic communities. Rising air and ocean temperatures, as well as glacier and sea-ice retreat, are impacting the conditions that support these systems. Projecting how these regions and their communities will evolve requires understanding both the large-scale climate variability and the regional-scale web of physical, biological, and social interactions. Here, we describe pan-Greenland physical, biological, and social settings and show how they are shaped by the ocean, the atmosphere, and the ice sheet. Next, we focus on two communities, Qaanaaq in Northwest Greenland, exposed to Arctic variability, and Ammassalik in Southeast Greenland, exposed to Atlantic variability. We show that while their climates today are similar to those of the warm 1930s­–1940s, temperatures are projected to soon exceed those of the last 100 years at both locations. Existing biological records, including fisheries, provide some insight on ecosystem variability, but they are too short to discern robust patterns. To determine how these systems will evolve in the future requires an improved understanding of the linkages and external factors shaping the ecosystem and community response. This interdisciplinary study exemplifies a first step in a systems approach to investigating the evolution of Greenland’s coastal margins.