Abstract
Abstract. Besides its negative trend, the interannual and the interdecadal changes in the Arctic sea ice have also been pronounced in recent decades. The three leading modes in the sea level pressure (SLP) variability in the Arctic (70–90∘ N) – the Arctic Oscillation (AO), the Arctic Dipole (AD), and the third mode (A3) – are analyzed to understand the linkage between sea ice variability and large-scale atmospheric circulation in boreal summer (June–August). This study also compares the decadal changes of the modes between the early (1982–1997) and the recent (1998–2017) periods and their influences on the Arctic sea ice extent (SIE). Only the AD mode shows a significant correlation increase with SIE in summer (JJA) from −0.05 in the early period to 0.57 in the recent period. The AO and the A3 modes show a less significant relationship with SIE for the two periods. The AD is characterized by a dipole pattern of SLP, which modulates the strength of meridional surface winds and the Transpolar Drift Stream (TDS). The major circulation change in the late 1990s is that the direction of the wind has been changed more meridionally over the exit region of the Fram Strait, which causes sea ice drift and discharge through that region. In addition, the response of surface albedo and the net surface heat flux becomes larger and much clearer, suggesting a positive sea-ice–albedo feedback in the sea ice variability associated with the AD. The analysis also reveals that the zonal shift of the centers of SLP anomalies and associated circulation change affects a significant reduction in sea ice concentration over the Pacific sector of the Arctic Ocean. This study further suggests that the Pacific Decadal Oscillation (PDO) phase change could influence the spatial pattern change in the AD.
Highlights
Arctic sea ice has experienced a radical change recently, with the record-breaking minimum in the sea ice extent (SIE) in 2012 (Parkinson and Comiso, 2013)
The winter Arctic Oscillation (AO) can modulate the summer sea ice variability (Rigor et al, 2002; Park et al, 2018), and the strong negative Arctic Dipole (AD) is considered the major driver for sea ice minimum in the 2007 summer (Wang et al, 2009)
This study examined the relationship between the sea ice and the Arctic atmospheric circulations separated by EOF analysis
Summary
Arctic sea ice has experienced a radical change recently, with the record-breaking minimum in the sea ice extent (SIE) in 2012 (Parkinson and Comiso, 2013). This mode is associated with a meridional wind dominantly, which tends to affect the meridional sea ice transport from the Arctic to the Atlantic in boreal winter (Wu et al, 2006; Watanabe et al, 2006) These circulation mode changes affect the Arctic sea ice distribution in winter and in summer, and both the AO and AD modes were linked with the September SIE variability in the previous studies. This study focuses on the decadal change in the leading SLP modes in the Arctic It aims to address the statistical relationship between large-scale atmospheric circulation and the Arctic sea ice variability in the interannual timescale and their decadal changes during boreal summer.
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