TY - JOUR
T1 - Glacier Calving Rates Due to Subglacial Discharge, Fjord Circulation, and Free Convection
AU - Schild, K. M.
AU - Renshaw, C. E.
AU - Benn, D. I.
AU - Luckman, A.
AU - Hawley, R. L.
AU - How, P.
AU - Trusel, L.
AU - Cottier, F. R.
AU - Pramanik, A.
AU - Hulton, N. R.J.
N1 - Funding Information:
We would like to thank the New Hampshire Space Grant Consortium (award # NNX15AH79H) for the training grant to fund KMS; the ConocoPhillips-Ludin Northern Area Program (under the CRIOS project) and the Dartmouth Graduate Studies Travel fund for their financial support to conduct fieldwork and travel for data dissemination; the Polar Geospatial Center for arranging access to the WorldView-2 imagery; the UK Natural Environmental Research Council (NERC) Oceans 2025 and Northern Sea Program for mooring work support, with further support from the Research Council of Norway (NFR) projects: Circa (214271), Cleopatra (178766), Cleopatra II (216537), and Marine Night (226471); Alex Hart and the GeoSciences Mechanical Workshop at the University of Edinburgh for manufacturing the time-lapse camera enclosure that was used in this study; Colin Griffiths (SAMS) and Jørgen Berge (UiT) for overseeing the collection of mooring data in Kongsfjorden since 2002; ESA for processing the Copernicus Sentinel data (2016). A video of the Sentinel imagery used in this study (doi:10.18739/A2NZ80P8K), as well as the raw time-lapse imagery (doi:10.18739/A2SQ8QH3F), mooring ocean temperature data, and CTD cast measurements (doi:10.18739/A2XG9F97K) are all available at the Arctic Data Center. Lastly, we would like to thank Bryn Hubbard and the four anonymous reviewers for their very helpful and thorough reviews.
Funding Information:
We would like to thank the New Hampshire Space Grant Consortium (award # NNX15AH79H) for the training grant to fund KMS; the ConocoPhillips- Ludin Northern Area Program (under the CRIOS project) and the Dartmouth Graduate Studies Travel fund for their financial support to conduct fieldwork and travel for data dissemination; the Polar Geospatial Center for arranging access to the WorldView-2 imagery; the UK Natural Environmental Research Council (NERC) Oceans 2025 and Northern Sea Program for mooring work support, with further support from the Research Council of Norway (NFR) projects: Circa (214271), Cleopatra (178766), Cleopatra II (216537), and Marine Night (226471); Alex Hart and the GeoSciences Mechanical Workshop at the University of Edinburgh for man ufacturing the time-lapse camera enclosure that was used in this study; Colin Griffiths (SAMS) and Jørgen Berge (UiT) for overseeing the collection of mooring data in Kongsfjorden since 2002; ESA for processing the Copernicus Sentinel data (2016). A video of the Sentinel imagery used in this study (doi:10.18739/A2NZ80P8K), as well as the raw time-lapse imagery (doi:10.18739/A2SQ8QH3F), mooring ocean temperature data, and CTD cast measurements (doi:10.18739/ A2XG9F97K) are all available at the Arctic Data Center. Lastly, we would like to thank Bryn Hubbard and the four anonymous reviewers for their very helpful and thorough reviews.
Publisher Copyright:
©2018. The Authors.
PY - 2018/9
Y1 - 2018/9
N2 - Tidewater glacier calving provides the most direct mechanism of ice transfer from land to the ocean. However, the physical melt processes influencing calving remain challenging to constrain. In this study we focus on calving rates at Kongsbreen, a tidewater glacier in Svalbard, due to three mechanisms of submarine melt: (1) free convection, (2) horizontal fjord circulation, and (3) meltwater discharge. To calculate an overall calving rate, we measure glacier velocity and terminus change using Sentinel imagery. We calculate free convection, fjord circulation, and meltwater discharge calving using mooring data for mid-fjord ocean temperature (30–80 m depth), reanalysis results for meltwater runoff, and georectified time-lapse imagery to track icebergs and infer surface circulation. Results show that the total glacier calving rate is highly correlated with ocean temperature during the 2016 melt season. When runoff was present, we found that subglacial discharge accounted for calving rates an order of magnitude greater than the maximum calving rates assigned to the other two melting mechanisms combined. Further, subglacial discharge at Kongsbreen was more efficient in inducing calving later in the season than earlier in the season, implying that the increase in ocean temperatures, the timing of meltwater discharge within a melt season, and/or the development of discrete meltwater exit channels are critical components to calving rates. As the recent atmospheric warming trend and subsequent increase in meltwater discharge is expected to continue, it is essential to understand the processes contributing to an increase in glacier calving and incorporate these processes into predictive models.
AB - Tidewater glacier calving provides the most direct mechanism of ice transfer from land to the ocean. However, the physical melt processes influencing calving remain challenging to constrain. In this study we focus on calving rates at Kongsbreen, a tidewater glacier in Svalbard, due to three mechanisms of submarine melt: (1) free convection, (2) horizontal fjord circulation, and (3) meltwater discharge. To calculate an overall calving rate, we measure glacier velocity and terminus change using Sentinel imagery. We calculate free convection, fjord circulation, and meltwater discharge calving using mooring data for mid-fjord ocean temperature (30–80 m depth), reanalysis results for meltwater runoff, and georectified time-lapse imagery to track icebergs and infer surface circulation. Results show that the total glacier calving rate is highly correlated with ocean temperature during the 2016 melt season. When runoff was present, we found that subglacial discharge accounted for calving rates an order of magnitude greater than the maximum calving rates assigned to the other two melting mechanisms combined. Further, subglacial discharge at Kongsbreen was more efficient in inducing calving later in the season than earlier in the season, implying that the increase in ocean temperatures, the timing of meltwater discharge within a melt season, and/or the development of discrete meltwater exit channels are critical components to calving rates. As the recent atmospheric warming trend and subsequent increase in meltwater discharge is expected to continue, it is essential to understand the processes contributing to an increase in glacier calving and incorporate these processes into predictive models.
UR - http://www.scopus.com/inward/record.url?scp=85053452304&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85053452304&partnerID=8YFLogxK
U2 - 10.1029/2017JF004520
DO - 10.1029/2017JF004520
M3 - Article
AN - SCOPUS:85053452304
SN - 2169-9003
VL - 123
SP - 2189
EP - 2204
JO - Journal of Geophysical Research: Earth Surface
JF - Journal of Geophysical Research: Earth Surface
IS - 9
ER -