Analysis of significant stratospheric ozone reductions over southern Brazil: A proposal for a diagnostic index for southern South America

• Published in: Meteorological Applications
• Main Authors: Rasera, Gustavo, Anabor, Vagner, Steffenel, Luiz Angelo, Pinheiro, Damaris Kirsch, Puhales, Franciano Scremin, Rodríguez, Lissette Guzmán, Peres, Lucas Vaz
• Other Authors: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: Antarctic; The Antarctic; Antarc*
• Online Access: http://dx.doi.org/10.1002/met.2034; https://onlinelibrary.wiley.com/doi/pdf/10.1002/met.2034; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/met.2034; https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/met.2034

Abstract During the southern spring, a break of the polar vortex over the Antarctic continent frequently occurs. This results in the advection of ozone‐poor air mass (O 3 ) to mid‐latitudes, characterizing the secondary effect of the Antarctic ozone hole (SEAOH). We present some distinct characteristics the eight greatest reductions of the total O 3 column (TOC) over the central region of Rio Grande do Sul (RS, 29.5°S, 54°W), southern Brazil, between August and November from 2012 to 2016 and develop a full scalar diagnostic index of O 3 negative anomalies for South America. For developing the index, mean values of the absolute potential vorticity, geopotential height, and wind components were obtained over moving grids with positive and negative O 3 anomalies. It was then possible to develop statistical methods to obtain a diagnostic index of the SEAOH (Subantarctic O 3 Index), as well as a diagnostic index of incursions of ozone‐poor air masses from the tropics (Subtropical O 3 Index). The results show that TOC over the central region of RS, for the most intense O 3 reduction episodes, is governed by a wide range of contributions from high and low isentropic levels. Significant interaction of air masses of polar and tropical origin via stratosphere–troposphere exchange was found. Finally, the Subantarctic O 3 Index combined with the Subtropical O 3 Index showed potential use for prediction centres and was skilful in detecting regions with the most negative O 3 anomalies, mainly in the mid‐latitude region, but also in the subtropical region.