Friday April 1 CSL Meeting

Fingerprinting the Drivers of Arctic Liquid Freshwater Change in a Large Ensemble Model

Abstract: Dramatic changes within the freshwater cycle have been observed in both the terrestrial and oceanic systems, and are expected to continue and even accelerate in a warming climate. Recent work has also identified the emergence of an external forcing signal beyond the internal variability of the Arctic freshwater balance. While Arctic liquid freshwater content is inherently linked to wind-driven processes on the ocean surface, such as the Arctic Oscillation and the Beaufort High, the contributing sources of potential liquid freshwater from increased sea ice cover melt, increased net-precipitation, and increased river runoff into the Arctic Ocean are all at least partially forced by anthropogenic-driven warming. Through analysis of a fully coupled climate model that accurately reproduces the spatial distribution and pattern of liquid freshwater content, we use a pattern matching technique to isolate and estimate the contribution of these signals within recent freshwater changes. Initial results confirm a large externally forced pattern in the multi-decadal freshwater increase, with a notable difference between the interior ocean and continental shelf, hinting at the importance of different freshwater sources and their respective drivers.

Simulated linear trends of liquid freshwater content in observations (ORAS5), the EC-Earth3 22-member ensemble mean, and the ensemble averages of the fastest (3 runs) and slowest (4 runs) increasing members in EC-Earth3, respectively, from 1958 to 2014.