A Steady Regime of Volume and Heat Transports in the Eastern Arctic Ocean in the Early 21st Century

Abstract

Mooring observations in the eastern Eurasian Basin of the Arctic Ocean showed that mean 2013–2018 along-slope volume and heat (calculated relative to the freezing temperature) transports in the upper 800 m were 4.8 ± 0.1 Sv (1 Sv = 106 m3/s) and 34.8 ± 0.6 TW, respectively. Volume and heat transports within the Atlantic Water (AW) layer (∼150–800 m) in 2013–2018 lacked significant temporal shifts at annual and longer time scales: averaged over the two periods of mooring deployment in 2013–2015 and 2015–2018, volume transports were 3.1 ± 0.1 Sv, while AW heat transports were 31.3 ± 1.0 TW and 34.8 ± 0.8 TW. Moreover, the reconstructed AW volume transports over longer, 2003–2018, period of time showed strong interannual variations but lacked a statistically significant trend. However, we found a weak positive trend of 0.08 ± 0.07 Sv/year in the barotropic AW volume transport estimated using dynamic ocean topography (DOT) measurements in 2003–2014 – the longest period spanned by the DOT dataset. Vertical coherence of 2013–2018 transports in the halocline (70–140 m) and AW (∼150–800 m) layers was high, suggesting the essential role of the barotropic forcing in constraining along-slope transports. Quantitative estimates of transports and their variability discussed in this study help identify the role of atlantification in critical changes of the eastern Arctic Ocean.

On the Interplay between Freshwater Content and Hydrographic Conditions in the Arctic Ocean in the 1990s–2010s

“…Vertical diffusion of heat and salt favors further propagation of T and S anomalies from the AW layer upward to the halocline as evidenced from the coherent temperature changes in the AW core (250-300 m depth), the upper part of the AW layer (150-250m depth), and the lower halocline (70-150m depth; Figures 6 and 8a,b). The warm pulses found in our records manifest the strong influence of advective mechanisms associated with the AW inflows in the formation of warm and salt anomalies and the thermal and salt balance in the EB reported earlier in several studies (e.g., [18,22,[44][45][46][47]). The rise of the upper AW boundary in the EEB was less evident in the decadal distributions (Figure 7j-l) compared to that estimated from the reconstructed series at the Laptev Sea slope (Figure 8f).…”

Nutrient and Silicon Isotope Dynamics in the Laptev Sea and Implications for Nutrient Availability in the Transpolar Drift

“…(b) Laptev Sea region with the Arctic Boundary Current (mean volume transport at 125°E is from Pnyushkov et al. (2021) and given in Sverdrup (Sv, in 10 6 m 3 /s)) and potential freshwater pathways (mean annual freshwater transport for the Khatanga and Lena rivers is taken from R‐ArcticNET http://www.r-arcticnet.sr.unh.edu/ and for Kara Sea freshwater advected via the Vilkitsky Strait Current is taken from Janout et al. (2015)).…”

Structure and Seasonal Variability of the Arctic Boundary Current North of Severnaya Zemlya

“…(2019). Downstream in the Laptev Sea, the ABC advects on average 4.8 ± 0.1 Sv in the top 800 m (Pnyushkov et al., 2021). However, a direct comparison between Severnaya Zemlya and Laptev Sea is difficult due to the broader distance that the measurements cover in the Laptev Sea.…”