Decadal coherence of Arctic thermohaline staircase

Thermohaline staircase layers have been consistently observed in the Arctic Ocean for over 50 years. Previous studies demonstrate that these structures exhibit large-scale spatial coherence. However, on time scales beyond a few years, both the coherence and evolution of the layers are unknown. Using Ice-Tethered Profiler data from 2005–2022 in the Beaufort Gyre Region, we track staircase layers across time and space with an unsupervised clustering method. Individual layers are found to be coherent across the entire 17-year time period, with properties that appear to evolve on 40–50 year timescales or longer. This establishes, for the first time, the decadal-scale coherence of thermohaline staircases in the Arctic Ocean. Moreover, we find that the observed changes are not consistent with the staircase being in a state of equilibrium, but rather support the hypothesis that it is decaying slowly from an initial or on-going perturbation.