Coastal Freshening Prevents Fjord Bottom Water Renewal in Northeast Greenland: A Mooring Study From 2003 to 2015

Abstract

The freshwater content of the Arctic Ocean and its bordering seas has recently increased. Observing freshening events is an important step toward identifying the drivers and understanding the effects of freshening on ocean circulation and marine ecosystems. Here we present a 13 year (2003–2015) record of temperature and salinity in Young Sound‐Tyrolerfjord (74°N) in Northeast Greenland. Our observations show that strong freshening occurred from August 2005 to August 2007 (−0.92 psu or −0.46 psu yr−1) and from August 2009 to August 2013 (−0.66 psu or −0.17 psu yr−1). Furthermore, temperature‐salinity analysis from 2004 to 2014 shows that freshening of the coastal water (~range at sill depth: 33.3 psu in 2005 to 31.4 psu in 2007) prevented renewal of the fjord's bottom water. These data provide critical observations of interannual freshening rates in a remote fjord in Greenland and in the adjacent coastal waters and show that coastal freshening impacts the fjord hydrography, which may impact the ecosystem dynamics in the long term.

Spring Succession and Vertical Export of Diatoms and IP25 in a Seasonally Ice-Covered High Arctic Fjord

“…The duration of the ensuing open-water season has increased since 2000 and currently lasts ∼3 months, until late October or early November. A continuous time series of temperature and salinity in the vicinity of our study location is presented in Boone et al (2018) and underlines a stepwise freshening of the fjord's subsurface and deep waters from 2003 to 2015 (see also Sejr et al, 2017). The fjord's hydrography also experiences important seasonal variation in salinity, with values ranging from 17 to 33.4‰, and 32.25 to 32.50‰, respectively, in the summer, and winter of 2013-2014 (Boone et al, 2018).…”

“…90 km long, and 2-7 km wide fjord system connected to the Greenland Sea. Along the eastern shelf of Greenland, the coastal waters are influenced by the East Greenland Current, which consists of Polar Surface Waters of low temperature (< 0 • C), and salinity (<34.4‰), overlying relatively warmer (0-2 • C), saline (>34‰), Atlantic waters (>150 m depth) (Boone et al, 2018). In the fjord system, however, a shallow sill of ca.…”

“…A continuous time series of temperature and salinity in the vicinity of our study location is presented in Boone et al (2018) and underlines a stepwise freshening of the fjord's subsurface and deep waters from 2003 to 2015 (see also Sejr et al, 2017). The fjord's hydrography also experiences important seasonal variation in salinity, with values ranging from 17 to 33.4‰, and 32.25 to 32.50‰, respectively, in the summer, and winter of 2013-2014 (Boone et al, 2018). Both the seasonal sea-ice melt and river runoff (0.63-1.57 km 3 yr −1 ; Mernild et al, 2007) contribute to the formation of a shallow surface lens of fresher water (5-10 m; S<25‰) from the end of June to July (Rysgaard et al, 1999;Sejr et al, 2017).…”

Review Article: How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?

“…The fjord system has a surface area of 390 km 2 , a length of 90 km, and a maximum depth of 360 m. A shallow ~45 m deep sill restricts exchange with the Greenland shelf and summertime productivity in the fjord is among the lowest measured in the Arctic (as low as <40 mg C m -2 day -1 ). In recent years, fjord waters have freshened (Sejr et al, 2017), and freshening of coastal waters has prevented renewal of fjord bottom waters (Boone et al, 2018). A data portal is available reporting work done in the catchment through the Greenland Ecosystem Monitoring Programme (GEM; http://g-e-m.dk).…”

Local Coastal Water Masses Control Heat Levels in a West Greenland Tidewater Outlet Glacier Fjord

“…Models of conceptual fjord systems show a strong impact of warm coastal water on glacier dynamics (e.g., Carroll et al, ). However, validation of these conceptually modeled fjord systems is often lacking as seasonal observations from fjords in Greenland are sparse, and only a few fjord systems have been studied extensively year‐round, for example, Young Sound (Boone et al, ; Rysgaard & Glud, ), Godthåbsfjord (Mortensen et al, , ), Sermilik, and Kangerlussuaq Fjords (Jackson et al, ).…”