Arctic Ocean Response to Greenland Sea Wind Anomalies in a Suite of Model Simulations

Abstract

Multimodel Arctic Ocean “climate response function” experiments are analyzed in order to explore the effects of anomalous wind forcing over the Greenland Sea (GS) on poleward ocean heat transport, Atlantic Water (AW) pathways, and the extent of Arctic sea ice. Particular emphasis is placed on the sensitivity of the AW circulation to anomalously strong or weak GS winds in relation to natural variability, the latter manifested as part of the North Atlantic Oscillation. We find that anomalously strong (weak) GS wind forcing, comparable in strength to a strong positive (negative) North Atlantic Oscillation index, results in an intensification (weakening) of the poleward AW flow, extending from south of the North Atlantic Subpolar Gyre, through the Nordic Seas, and all the way into the Canadian Basin. Reconstructions made utilizing the calculated climate response functions explain ∼50% of the simulated AW flow variance; this is the proportion of variability that can be explained by GS wind forcing. In the Barents and Kara Seas, there is a clear relationship between the wind‐driven anomalous AW inflow and the sea ice extent. Most of the anomalous AW heat is lost to the atmosphere, and loss of sea ice in the Barents Sea results in even more heat loss to the atmosphere, and thus effective ocean cooling. Release of passive tracers in a subset of the suite of models reveals differences in circulation patterns and shows that the flow of AW in the Arctic Ocean is highly dependent on the wind stress in the Nordic Seas.

Sea Ice—Ocean Interactions in the Barents Sea Modeled at Different Resolutions

“…The models with higher mean OHT at the Barents Sea Opening (large transect) have lower mean March Barents sea-ice area (R = −0.94; Figure 8A). This result is in agreement with Mahlstein and Knutti (2011), who focus on the relationship between northward Atlantic OHT and Arctic sea-ice extent in CMIP3 models, and Muilwijk et al (2019), who find such a link using nine different climate models. The trends in OHT at the Barents Sea Opening and March Barents sea-ice area are weakly correlated to the mean OHT at the Barents Sea Opening (R = 0.17 and −0.26, respectively; Figures 8B,C).…”

“…Koenigk and Brodeau (2014) show the leading role of OHT in the current Barents sea-ice reduction using the EC-Earth model. Muilwijk et al (2019) use eight different oceanonly models and one fully coupled model, which have different resolutions, domains (both global and regional) and atmospheric forcing, and which are perturbed by adding the same wind anomaly over the Greenland Sea. They find that a stronger wind forcing leads to an increased OHT at the Barents Sea Opening and a reduced Barents sea-ice area.…”

Understanding Arctic Ocean Circulation: A Review of Ocean Dynamics in a Changing Climate

“…While conceptual models provide the context in which to contemplate the Arctic's changing dynamics as the Earth warms, we require continued exploration of novel ways to make use of atmosphere‐ocean‐sea‐ice coupled general circulation models to probe the Arctic system response to external drivers (as described by, e.g., Johnson et al, ; Marshall et al, ; Muilwijk et al, ). These modeling efforts require constraints provided by sustained observations.…”

Introduction to Special Collection on Arctic Ocean Modeling and Observational Synthesis (FAMOS) 2: Beaufort Gyre Phenomenon

“…With a focus on modeling, there are several papers that employ a new approach using "climate response functions" to better understand processes of Arctic and subarctic variability and predict future Arctic change (e.g., Brown et al (2019); Lambert et al, 2019;Muilwijk et al, 2019).…”

“…Past studies suggest that the Atlantic water underlying the Pacific winter water layer most likely circulates cyclonically-in the opposite sense to the shallower layers (e.g., Häkkinen & Mellor, 1992;Karcher et al, 2007Karcher et al, , 2012Nazarenko et al, 1998;Rudels et al, 1994;Treshnikov & Baranov, 1972). Atlantic water heat transport toward the Arctic Ocean is discussed by Muilwijk et al (2019) in this special collection.…”