Antarctic tropopause by ozonesonde profiles from the Polar Atmospheric Chemistry at the Tropopause PACT database

Abstract

Stratosphere–troposphere exchange can be considered globally within the framework of the atmosphere's general circulation as the transfer of air masses through the tropopause with ascending (descending) flows in the tropics (extratropical latitudes). The report aims to study the features and behavior of thermal and chemical tropopause to determine the troposphere-stratosphere interaction in the ozone hole in the Antarctic region. To calculate the height of the polar tropopause based on vertical temperature profiles (thermal tropopause), ozone profiles (ozone tropopause), and water vapor ("water" tropopause), we used the Polar Atmospheric Chemistry at the Tropopause (PACT) database that provides high-resolution measurements from polar ozonesondes flown from selected Antarctic sites. The vertical resolution of the raw ozonesonde measurements is typically 10 meters, which allows us to determine the tropopause height with high accuracy. We calculated the monthly mean ozone and thermal tropopause height variations from the PACT data. Seasonal thermal tropopause and ozone tropopause height monthly changes at the selected Antarctic stations were examined. We developed an algorithm for determining the tropopause height based on vertical profiles of water vapor, studied the relative position of the three tropopauses by altitude, and revealed the anticorrelation of the water and thermal tropopauses. The analysis shows that during the ozone hole formation period in August–September, the vertical stability of the upper troposphere and lower stratosphere is disturbed, and the ozone tropopause can drop below the thermal one, which can create conditions for the spread of stratospheric air into the troposphere and cause conditions for the stratosphere–troposphere exchange.This work was partly supported by the projects of the Australian Antarctic Division and by the International Center of Future Science, Jilin University, under Grant No G2023129024.