Transient tracers, water mass ages and mixing time scales in the Arctic Ocean

Smith and colleagues determined iodine-129 (129I), chlorofluorocarbons (CFC-11) and sulfur hexafluoride (SF6), in the Arctic Ocean in samples collected during two U.S. and one German GEOTRACES cruises that occurred in 2015 (cruises GN01 and GN04). The resulting large, quasi-synoptic tracer data sets provide an opportunity to use these transient tracers to determine water mass mean ages and mixing rates in a highly stratified, arctic, marine system. Their calculated mean age sections are conform to historical ideas of tracer ages while the mixing time is nearly constant in upper intermediate water, which reflects the influence of strong advective flow. The high mixing values found in the upper halocline are congruent with the nutrient maximum indicating that both are governed by winter shelf mixing processes.

Figure: Left panels: Tracer sections across Canada Basin and Eurasian Basin for; (a) CFC-11; (b) SF6 and (c) 129I. Right panels: Tracer sections across Makarov and Eurasian Basin for; (d) CFC-11; (e) SF6 and (f) 129I. Maps of respective tracer sections are illustrated in top panels.


Smith, J. N., Smethie Jr., W. M., & Casacuberta, N. (2022). Synoptic 129 I and CFC–SF 6 Transit Time Distribution (TTD) Sections Across the Central Arctic Ocean From the 2015 GEOTRACES Cruises. Journal of Geophysical Research: Oceans, 127(9). Access the paper: 10.1029/2021jc018120

Latest highlights

Science Highlights

Decline of the anthropogenic lead imprint to the ocean confirmed by data from the South West Atlantic Ocean

This study reveals that the mean lead concentrations in the surface waters of the western South Atlantic Ocean decreased by 34 % between the 1990s and 2011.


Science Highlights

Irradiance-normalized non-photochemical quenching (NPQ): a new proxy of iron stress for phytoplankton

Ryan-Keogh and his colleagues used NPQ to fingerprint the photo-physiological response of phytoplankton to their environment.


Science Highlights

Exhaustive modelling study of the oceanic neodymium parameters

The conclusion of this study reinforces the important role of the solid particles in driving the neodymium oceanic cycle.


Science Highlights

Dissolved manganese distribution in the Arabian Sea reveals many variable triggers

Analysis of dissolved manganese on samples collected on GEOTRACES cruises allowed Singh and colleagues to establish its basin-wide distribution in the Arabian Sea.