| Summary: | While the zonal mean signals associated with the quasi-biennial oscillation (QBO) in stratospheric ozone have been relatively well documented, the zonal (longitudinal) differences have been less studied. Using satellite-based ozone data, ERA5 reanalysis and model simulations, we demonstrate that the influences of QBO on stratospheric ozone and total column ozone (TCO) are seasonally dependent zonally asymmetric. During boreal winter (DJF), positive anomalies of TCO and stratospheric ozone are evident during QBO westerly (QBOW) phases over the regions from North America to the North Atlantic (120˚ W–30˚ E), while significant negative anomalies exist over other longitudes in the Arctic. In boreal autumn (SON), TCO and stratospheric ozone are anomalously high during QBOW from Greenland to Eurasia (60˚ W–120˚ E) but anomalously low in other regions over the Arctic. Weak positive TCO and stratospheric ozone anomalies exist over the South America sector (90˚ W–30˚ E) of the Antarctic, while negative anomalies of TCO and stratospheric ozone are seen in other longitudes. Analysis of meteorological conditions indicates that the QBO ozone perturbations are mainly caused by dynamical transport. QBO affects the geopotential height and the polar vortex and subsequently the transport of ozone-rich air from lower latitudes to the polar region, which therefore influences the ozone concentrations over the polar region. The geopotential height anomalies associated with QBO (QBOW–QBOE) are zonally asymmetric with clear wave number 1 features, which indicates that QBO influences the polar vortex and stratospheric ozone mainly by modifying the wave number 1 activities.
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