Investigation of the behavior of the atmospheric dynamics during occurrences of the ozone hole's secondary effect in southern Brazil

Abstract

Abstract. The Antarctic ozone hole (AOH) directly influences the Antarctic region, where its levels can reach values below 220 DU. The temporary depletion of ozone in Antarctica generally occurs between the beginning and middle of August, during the austral spring, and extends to November, when a temporary reduction in ozone content is observed in a large region over the Antarctic continent. However, masses of ozone-depleted air can break away from the ozone hole and reach mid-latitude regions in a phenomenon known as the secondary effect of the Antarctic ozone hole. The objective of this paper is to show how atmospheric dynamics behave during the occurrence of this type of event, especially in mid-latitude regions, such as southern Brazil, over a 12-year observation period. For the analysis and identification of the events of influence of the AOH on the southern region of Brazil, data from the total ozone column were used from ground-based and satellite experiments, the Brewer Spectrophotometer (MkIII no. 167), and the Ozone Monitoring Instrument (OMI) on the Aura satellite. For the analysis of the stratospheric and tropospheric fields, the ECMWF reanalysis products were used. Thus, 37 events of influence of the AOH that reached the southern region of Brazil were identified for the study period (2006–2017), where the events showed that in approximately 70 % of the cases they occurred after the passage of frontal systems and/or atmospheric blocks over southern Brazil. In addition, the statistical analysis showed a strong influence of the jet stream on mid-latitude regions during the events. Among the 37 identified events, 92 % occurred in the presence of the subtropical and/or polar jet stream over the region of study, possibly explaining the exchange of air masses of ozone deficient in the upper troposphere–lower stratosphere (UT–LS) region.

Forecasting upper atmospheric scalars advection using deep learning: an $$O_3$$ experiment

“…In this section, we concentrate our analysis on a list of 24 OSE compiled by Bittencourt et al (2019). These events occur during the Austral Spring and are tightly related to the "opening" of the South Pole Ozone hole and the breaking of the polar vortex.…”

“…Secondary effects of the Antarctic Ozone Hole in mid-latitude zones are regularly observed above populated zones in South America, south of Africa, and New Zealand. Indeed, ground observations reported the occurrence of dozens of OSEs in the last decades above the south of Brazil (Bittencourt et al 2019), resulting in temporary reductions in the total ozone column of more than 10% over densely populated areas. According to the latest World Meteorological Organization (WMO) reports Project 2014, 2018), there is a growth trend between the 1980s and 1990s, stabilizing at high rates since the year 2000 despite indications of declining trends in Antarctic ozone in recent years (Solomon et al 2016).…”

“…It is also important to note that most works on OSE limit to the study of past events (Canziani et al 2002;Bencherif et al 2011;Peres 2013;Bittencourt et al 2019), whose characterization depends on several indirect factors besides the O 3 Total Column. For example, Potential Vorticity (PV) has been used to identify air masses originated in the pole, confirmed by a retroactive trajectory analysis using the HYSPLIT model (Stein et al 2016).…”

Multi-instrumental analysis of ozone vertical profile and total column in South America: comparison between subtropical and equatorial latitudes

“…The position and speed of these jets (subtropical or polar) as a function of the meridional temperature gradient can determine the variation of ozone in the atmosphere (Reboita et al, 2010;Bukin et al, 2011). These dynamical context in subtropical latitudes have significant relevance in studies with O 3 , because they have an indirect relationship with the Antarctic Ozone Hole (AOH) which modifies the O 3 content in the region mainly during the austral spring through the ejection of masses from air poor in O 3 content from the polar region, where the Antarctic Ozone Hole is located, to regions of subtropical latitudes, as is the case of SM (Kirchhoff et al, 1996;Vaz Peres et al, 2017;Bittencourt et al, 2018Bittencourt et al, , 2019. The equatorial region of Brazil (NT) presents a barotropic atmosphere without a large variation in the temperature gradient.…”

Satellite-based estimation of NO2 concentrations using a machine-learning model: a case study on Rio Grande do Sul, Brazil

“…An example of the lack of an extensive network for environmental monitoring is Rio Grande do Sul State, located in south Brazil, with only nine stations within its borders. Compared to other regions of the country, the State is exposed to higher levels of ultraviolet radiation for being closer to the Antarctic ozone hole (Kirchhoff et al, 2000;Guarnieri et al, 2004), and is strongly influenced by transient meteorological systems (cold and hot fronts), isentropic transport (between the tropical stratosphere reservoir, polar vortex, middlelatitude) and exchange processes (between upper troposphere-lower stratosphere) (Reboita et al, 2010;Bittencourt et al, 2019).…”