ENSO Modulates Summer and Autumn Sea Ice Variability Around Dronning Maud Land, Antarctica

Florence E Isaacs,Andrew N Mackintosh,Ruzica Dadic,James A Renwick

doi:10.1029/2020jd033140

Abstract

AbstractAntarctica’s sea ice cover is an important component of the global climate system, yet the drivers of sea ice variability are not well understood. Here we investigated the effects of climate variability on sea ice concentration (SIC) around East Antarctica by correlating the 40‐years (1979–2018) satellite sea ice record and ERA5 reanalysis data. We found that summer and autumn SIC around Dronning Maud Land (DML) between 10 and 70°E exhibited a statistically significant negative correlation with the Niño 3.4 index. Sea ice in DML was also correlated with sea surface temperature (SST) anomalies in the tropical Pacific, and to an atmospheric wave train pattern extending from the South Pacific to DML. We suggest that a southward‐propagating atmospheric wave train triggered by SST anomalies in the tropical Pacific extends into DML and alters sea ice concentration by encouraging meridional airflow. Our results showed that shifts in meridional flow in DML affected sea ice thermodynamically, by altering local heat transport and in turn altering sea ice formation and melt.

Highlights

Antarctic sea ice is an important component of the global climate system, modulating global circulation through changes to heat and moisture fluxes (Grotzner et al, 1996; Rind et al, 1995; Walsh, 1983), surface albedo (Curry et al, 1995), and production of deep ocean waters (Ferrari et al, 2014; Jacobs, 2004)
In the region around Dronning Maud Land (DML) where sea ice was significantly correlated with El Niño Southern Oscillation (ENSO), the sea ice zone demonstrated substantial seasonal and interannual variability
Our study identifies the first clear link between ENSO and sea ice concentration (SIC) in East Antarctica in the Dronning Maud Land sector

Summary

Introduction

Antarctic sea ice is an important component of the global climate system, modulating global circulation through changes to heat and moisture fluxes (Grotzner et al, 1996; Rind et al, 1995; Walsh, 1983), surface albedo (Curry et al, 1995), and production of deep ocean waters (Ferrari et al, 2014; Jacobs, 2004). Coupled sea-ice-climate models are currently unable to replicate current sea ice trends and variability in the Southern Ocean, predicting a negative trend where observations show a positive one (e.g., Comiso & Nishio, 2008; Polvani & Smith, 2013; Turner et al, 2013) highlighting the limitations in our understanding of the processes that drive sea ice change. Several studies have suggested that climate variability and tropical teleconnections such as those associated with El Niño Southern Oscillation (ENSO) may play a role in determining recent sea ice variability and trends (e.g., Meehl et al, 2016; Purich et al, 2016; Raphael & Hobbs, 2014; Simmonds & Jacka, 1995; Simpkins et al, 2012; Yuan & Li, 2008). Changes in the tropical atmospheric circulation propagate further into the global circulation, driving variability in precipitation (e.g., Barlow et al, 2001; Dai & Wigley, 2000; Ropelewski & Halpert, 1986), air temperatures (e.g., Power et al, 1999; Pozo-Vazquez et al, 2001; Smith & Sardeshmukh, 2000), ISAACS ET AL

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