Heat, salt, and freshwater budgets for a glacial fjord in Greenland
MetadataShow full item record
KeywordGeographic location/entity; Estuaries; Glaciers; Circulation/ Dynamics; Coastal flows; Atm/Ocean Structure/ Phenomena; Freshwater; Snowmelt/icemelt; Observational techniques and algorithms; In situ oceanic observations
In Greenland’s glacial fjords, heat and freshwater are exchanged between glaciers and the ocean. Submarine melting of glaciers has been implicated as a potential trigger for recent glacier acceleration, and observations of ocean heat transport are increasingly being used to infer the submarine melt rates. The complete heat, salt, and mass budgets that underlie such methods, however, have been largely neglected. Here, a new framework for exploring glacial fjord budgets is developed. Building on estuarine studies of salt budgets, the heat, salt, and mass transports through the fjord are decomposed, and new equations for calculating freshwater fluxes from submarine meltwater and runoff are presented. This method is applied to moored records from Sermilik Fjord, near the terminus of Helheim Glacier, to evaluate the dominant balances in the fjord budgets and to estimate freshwater fluxes. Throughout the year, two different regimes are found. In the nonsummer months, advective transports are balanced by changes in heat/salt storage within their ability to measure; freshwater fluxes cannot be inferred as a residual. In the summer, a mean exchange flow emerges, consisting of inflowing Atlantic water and outflowing glacially modified water. This exchange transports heat toward the glacier and is primarily balanced by changes in storage and latent heat for melting ice. The total freshwater flux increases over the summer, reaching 1200 ± 700 m3 s−1 of runoff and 1500 ± 500 m3 s−1 of submarine meltwater from glaciers and icebergs in August. The methods and results highlight important components of fjord budgets, particularly the storage and barotropic terms, that have been not been appropriately considered in previous estimates of submarine melting.
Author Posting. © American Meteorological Society, 2016. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 46 (2016): 2735-2768, doi:10.1175/JPO-D-15-0134.1.
Showing items related by title, author, creator and subject.
Dynamics of freshwater plumes : observations and numerical modeling of the wind-forced response and alongshore freshwater transport Fong, Derek A. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1998-06)A freshwater plume often forms when a river or an estuary discharges water onto the continental shelf. Freshwater plumes are ubiquitous features of the coastal ocean and usually leave a striking signature in the coastal ...
Proshutinsky, Andrey; Krishfield, Richard A.; Timmermans, Mary-Louise; Toole, John M.; Carmack, Eddy C.; McLaughlin, Fiona A.; Williams, William J.; Zimmermann, Sarah; Itoh, Motoyo; Shimada, Koji (American Geophysical Union, 2009-06-24)We investigate basin-scale mechanisms regulating anomalies in freshwater content (FWC) in the Beaufort Gyre (BG) of the Arctic Ocean using historical observations and data collected in 2003–2007. Specifically, the mean ...
Observations of a freshwater pulse induced by Typhoon Morakot off the northern coast of Taiwan in August 2009 Jan, Sen; Wang, Joe; Yang, Yiing-Jang; Hung, Chin-Chang; Chern, Ching-Sheng; Gawarkiewicz, Glen G.; Lien, Ren-Chieh; Centurioni, Luca R.; Kuo, Jia-Yu; Wang, Bee (Sears Foundation for Marine Research, 2013-01-01)In this paper we describe large-scale impacts from a typhoon on the circulation over the continental shelf and slope north of Taiwan. Typhoon Morakot was a category 2 tropical storm that landed in central Taiwan, but caused ...