A Changing Arctic Ocean: How Measured and Modeled 129I Distributions Indicate Fundamental Shifts in Circulation Between 1994 and 2015
METADATA ONLY
Loading...
Author / Producer
Date
2021-03
Publication Type
Journal Article
ETH Bibliography
yes
Citations
Altmetric
METADATA ONLY
Data
Rights / License
Abstract
129I measurements on samples collected during GEOTRACES oceanographic missions in the Arctic Ocean in 2015 have provided the first synoptic 129I sections across the Eurasian, Canada, and Makarov Basins. During the 1990s, increased discharges of 129I from European nuclear fuel reprocessing plants produced a large, tracer spike whose passage through the Arctic Ocean has been followed by 129I time series measurements over the past 25 years. Elevated 129I levels measured over the Lomonosov and Alpha‐Mendeleyev Ridges in 2015 were associated with tracer labeled, Atlantic‐origin water bathymetrically steered by the ridge systems through the central Arctic while lower 129I levels were evident in the more poorly ventilated basin interiors. 129I levels of 200–400 × 107 at/l measured in intermediate waters had increased by a factor of 10 in 2015 compared to 1994–1996 owing to the circulation of the 1990s, 129I input spike. Comparisons of 129I distributions between the mid‐1990s and 2015 delineate large scale circulation changes that occurred during the shift from a positive Arctic Oscillation and a cyclonic circulation regime in the mid‐1990s to anticyclonic circulation in 2015. The latter is characterized by a broadened Beaufort Gyre in the upper ocean, a weakened boundary current and partial mid‐depth, AW flow reversal in the southern Canada Basin. Tracer 129I simulations using the applied circulation model, NAOSIM, agree with both historical 129I results and recent GEOTRACES data sets, thereby supporting the present interpretation of the relationship of changes in arctic circulation to shifts in climate indices revealed by tracer 129I distributions. © 2021 American Geophysical Union
Permanent link
Publication status
published
External links
Editor
Book title
Journal / series
Volume
126 (3)
Pages / Article No.
Publisher
American Geophysical Union
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Organisational unit
09755 - Casacuberta Arola, Núria / Casacuberta Arola, Núria
Notes
Funding
154805 - A new multitracer approach in Oceanography: combining U-236 with conventional anthropogenic radionuclides in the Arctic and Atlantic Oceans (SNF)