Variability of upper troposphere–lower stratosphere ozone over East Asia from a perspective of atmospheric stationary waves

Abstract By analyzing observational reanalysis datasets since the late 20th century, in this study we investigated the monthly variability of East Asian ozone at the upper troposphere–lower stratosphere (UTLS, 250 hPa), from a perspective of atmospheric stationary waves. To identify the primary modes of East Asian UTLS ozone variability, an empirical orthogonal function (EOF) analysis was conducted, revealing that the first three EOF modes account for approximately two-thirds of the total variability. The first EOF mode, characterized by a monopole pattern, is associated with the Polar–Eurasian-like teleconnection. Additionally, the second and third EOF modes, featuring meridional and zonal dipole patterns, are linked to the West Pacific-like teleconnection and the British–Baikal Corridor-like teleconnection, respectively. It was found that UTLS ozone concentrations increase over troughs and decrease over ridges of these atmospheric stationary waves in the mid-latitudes. The increase in UTLS ozone concentration caused by these stationary atmospheric waves is expected to create favorable background conditions for a stronger intrusion of stratospheric ozone into the mid-troposphere. Additionally, our results indicate that stratospheric ozone can sustain these stationary atmospheric waves by modulating geopotential height through solar radiation absorption. These findings highlight the crucial role of dynamic-chemical interactions in advancing our understanding of the UTLS system.