Lasting impact of winds on Arctic sea ice through the ocean's memory

Qiang Wang,Claudia Wekerle,Longjiang Mu,Dmitry Sidorenko,Sergey Danilov

doi:10.5194/tc-15-4703-2021

Abstract

Abstract. In this paper we studied the impact of winds on Arctic sea ice through the ocean's memory by using numerical simulations. We found that the changes in halosteric height induced by wind perturbations can significantly affect the Arctic sea ice drift, thickness, concentration and deformation rates regionally even years after the wind perturbations. Changes in the Arctic liquid freshwater content and thus in halosteric height can cause changes in the sea surface height and surface geostrophic currents, which further enforce a lasting and strong impact on sea ice. The changes in both sea surface height gradient force (due to changes in sea surface height) and ice–ocean stress (due to changes in surface geostrophic currents) are found to be important in determining the overall ocean effects. The revealed ocean effects are mainly associated with changes in sea ice dynamics, not thermodynamics. Depending on the preceding atmospheric mode driving the ocean, the ocean's memory of the wind forcing can lead to changes in Arctic sea ice characteristics with very different spatial patterns. We obtained these spatial patterns associated with Arctic Oscillation, Arctic Dipole Anomaly and Beaufort High modes through dedicated numerical simulations. The dynamical impact of the ocean has strong seasonal variations, stronger in summer and weaker in winter and spring. This implies that declining trends of Arctic sea ice will very possibly allow a stronger ocean impact on the sea ice in a warming climate.

Highlights

Arctic sea ice has undergone significant changes over the period of satellite observations
By applying the wind perturbations, the magnitudes and spatial patterns of Arctic halosteric height and sea surface height were changed, as shown by their anomalies relative to the control run in the last year of the wind-perturbation simulations
The changes in sea surface height can be explained by the changes in halosteric height, which are associated with the changes in liquid freshwater content (Giles et al, 2012; Armitage et al, 2016; Wang, 2021a)

Summary

Introduction

Arctic sea ice has undergone significant changes over the period of satellite observations. The decline in Arctic sea ice thickness and extent is accompanied by pronounced variability on different timescales, with contributions from both dynamic and thermodynamic processes (Serreze and Meier, 2019). Wind variation associated with the Arctic Dipole Anomaly (DA) can significantly influence the Transpolar Drift, affecting Fram Strait sea ice export and Arctic summer sea ice extent (Wu et al, 2006; Wang et al, 2009; Kwok et al, 2013; Platov et al, 2020)

Methods

Results

Discussion

Conclusion