Comparison of the Dynamic Transport Characteristics of Low Ozone Regions over the Arctic and the Tibetan Plateau from 1979 to 2020

Based on the monthly ERA5 reanalysis datasets, this study considers the mean flows and eddies in stationary or transient transport using the Lorenz circulation decomposition method. The purpose is to compare the dynamic transport characteristics of ozone over the Arctic and the Tibetan Plateau in detail. Results show that the effect of dynamic transport is strongest in the upper stratosphere of these two regions, which leads to the reduction of ozone. Further analyses indicate that the effect of stationary transport is stronger than that of transient transport and zonal and meridional transports nearly have the opposite effect. However, the intensity of dynamic transport over the Arctic is greater than that over the Tibetan Plateau. Zonal transport over the Arctic results in the reduction of ozone in the upper and middle stratosphere and the increase of ozone in the lower stratosphere, whereas the effect of meridional transport is the opposite and weaker. Both mainly function in the upper stratosphere. Over the Tibetan Plateau, the intensity of zonal transport is the same as that of meridional transport. They nearly have the opposite effect, except for the top of the stratosphere, where both lead to the reduction of ozone. Two centers with the strongest transport are located over the Tibetan Plateau, that is, in the upper stratosphere and the upper troposphere–lower stratosphere. The differences in zonal and meridional transports over these two regions are mainly caused by stationary transport by eddies. The differences in stationary and transient transports over the Tibetan Plateau are smaller than those over the Arctic. Furthermore, the transport of zonal mean ozone by eddies plays a dominant role in stationary and transient transports. Consequently, eddy transport exerts an indispensable influence on the dynamic transport of ozone over the Arctic and the Tibetan Plateau.