Statistical Analysis of the Spatiotemporal Distribution of Ozone Induced by Cut-Off Lows in the Upper Troposphere and Lower Stratosphere over Northeast Asia

Abstract

This paper presents the results of a statistical study of the spatiotemporal distribution of ozone in the upper troposphere and lower stratosphere (UTLS) regions induced by cut-off lows (COLs) over Northeast Asia. The analysis was based on high-resolution ERA-Interim ozone data and Atmospheric Infrared Sounder (AIRS) satellite data for the period from 2005–2015. A total of 186 COL events were detected. The observed ozone distribution revealed an ozone-rich region in the upper troposphere (300 hPa) located around the center of the COLs at the time when COLs reached their maximum intensity. This region corresponds to a region of high potential vorticity (PV). In the middle troposphere (500 hPa), enhanced levels of the ozone were distributed in two regions. The maximum concentration was located to the east of the COLs, and a secondary maximum region was in the center of the COLs. Further analysis revealed that this spatial distribution of ozone in the upper troposphere was affected mainly by decreased tropopause. The ozone was subject to a ‘rotary’ transport process in the middle troposphere, influenced mainly by the anticlockwise circulation of the COLs and the surrounding horizontal wind distribution. The temporal variations in ozone anomalies also revealed the ozone distribution patterns and transport processes. The variation in ozone anomalies implied that the magnitude of the ozone increase was closely related to the evolution of COLs lifecycle. The temporal and spatial distributions of the ozone revealed by the statistical analysis of the AIRS satellite data were overall consistent with those of the ERA-Interim data.