Arctic Ocean Freshwater Content and Its Decadal Memory of Sea-Level Pressure

Helen L. Johnson , Sam B. Cornish , Yavor Kostov , Emma Beer , Camille Lique (1)

1 LOPS - Laboratoire d'Océanographie Physique et Spatiale

Arctic freshwater content (FWC) has increased significantly over the last two decades, with potential future implications for the Atlantic meridional overturning circulation downstream. We investigate the relationship between Arctic FWC and atmospheric circulation in the control run of a coupled climate model. Multiple linear lagged regression is used to extract the response of total Arctic FWC to a hypothetical step increase in the principal components of sea-level pressure. The results demonstrate that the FWC adjusts on a decadal timescale, consistent with the idea that wind-driven ocean dynamics and eddies determine the response of Arctic Ocean circulation and properties to a change in surface forcing, as suggested by idealized models and theory. Convolving the response of FWC to a change in sea-level pressure with historical sea-level pressure variations reveals that the recent observed increase in Arctic FWC is related to natural variations in sea-level pressure.

Keywords: Arctic Ocean; climate change; interannual variability; freshwater; adjustment timescales; ocean dynamics

Domains: Sciences of the Universe [physics]; Earth Sciences

Helen L. Johnson, Sam B. Cornish, Yavor Kostov, Emma Beer, Camille Lique. Arctic Ocean Freshwater Content and Its Decadal Memory of Sea-Level Pressure. Geophysical Research Letters, 2018, 45, pp.4991-5001. ⟨10.1029/2017GL076870⟩. ⟨insu-03683082⟩