The relationship between lower-stratospheric ozone at southern high latitudes and sea surface temperature in the East Asian marginal seas in austral spring

Wenshou Tian,Wuhu Feng,Martyn P Chipperfield,Yongyun Hu,Xuan Ma,Jiankai Zhang,Sen Zhao,Xin Zhou,Yuanpu Li,Fei Xie,Yun Yang

doi:10.5194/acp-17-6705-2017

Abstract

Abstract. Using satellite observations, reanalysis data, and model simulations, this study investigates the effect of sea surface temperature (SST) on interannual variations of lower-stratospheric ozone at southern high latitudes in austral spring. It is found that the SST variations across the East Asian marginal seas (5° S–35° N, 100–140° E) rather than the tropical eastern Pacific Ocean, where ENSO occurs, have the most significant correlation with the southern high-latitude lower-stratospheric ozone changes in austral spring. Further analysis reveals that planetary waves originating over the marginal seas in austral spring can propagate towards southern middle to high latitudes via teleconnection pathway. The anomalous propagation and dissipation of ultra-long Rossby waves in the stratosphere strengthen/cool (weaken/warm) the southern polar vortex, which produces more (less) active chlorine and enhances (suppresses) ozone depletion in the southern high-latitude stratosphere on one the hand and impedes (favors) the transport of ozone from the southern middle-latitude stratosphere to high latitudes on the other. The model simulations also reveal that approximately 17 % of the decreasing trend in the southern high-latitude lower-stratospheric ozone observed over the past 5 decades may be associated with the increasing trend in SST over the East Asian marginal seas.

Highlights

∗ Following the definition of El Niño–Southern Oscillation (ENSO) events (Trenberth 1997), we propose a threshold of ±0.2, which is equal to the standard deviation of the ST_MSEAI series, as the indicator of warm and cold events
We found that the Rossby waves generated by sea surface temperature (SST) anomalies in the marginal seas of East Asia could propagate to the middle to high latitudes of the Southern Hemisphere in austral spring and winter (Fig. 4a and d) but not in austral summer and autumn (Fig. 4b and c) because the Rossby waves motivated by the low-latitude SST anomalies move mostly northwards in austral summer and autumn
We found that SST over the marginal seas of East Asia can significantly modulate the interannual variability of austral spring southern high-latitude lower-stratospheric ozone and that the processes involved in this modulation are related to anomalous planetary wave activity induced by SST variations over the marginal seas of East Asia

Summary

Introduction

Ozone variations over recent decades exhibit strong trends, forced by changes in ozone-depleting substances superimposed on a changing climate, and interannual variability influenced by various external and internal climate forcings (e.g., Manney et al, 1994; Müller et al, 1994, 2005; Weiss et al, 2001; Hadjinicolaou et al, 2002; Tian and Chipperfield, 2005; Austin et al, 2006, 2010; Eyring et al, 2010; Liu et al, 2011, 2013; Douglass et al, 2014). The cold (warm) polar vortex (Fig. 10a and c) allows more (less) PSCs/active chlorine (Fig. 10b and d) to form This is one process through which SST variations over the marginal seas of East Asia cause southern high-latitude lower-stratospheric ozone changes. The southern high-latitude lower-stratospheric ozone variations caused by the SST variability over the marginal seas of East Asia can be obtained by subtracting simulated ozone in the ensemble experiments ((T2 + T3)/2)) from the ozone in T1 (Fig. 14, black line).

Experiments

Findings

Conclusions and summary