The Antarctic ozone hole is a cyclical phenomenon that occurs during the austral spring where there is a large decrease in ozone content in the Antarctic region. Ozone-poor air mass can be released and leave through the Antarctic ozone hole, thus reaching midlatitude regions. This phenomenon is known as the secondary effect of the Antarctic ozone hole. The objective of this study is to show how tropospheric and stratospheric dynamics behaved during the occurrence of this event. The ozone-poor air mass began to operate in the region on 20 October 2016. A reduction of ozone content of approximately 23 % was observed in relation to the climatology average recorded between 1992 and 2016. The same air mass persisted over the region and a drop of 19.8 % ozone content was observed on 21 October. Evidence of the 2016 event occurred through daily mean measurements of the total ozone column made with a surface instrument (Brewer MkIII no. 167 Spectrophotometer) located at the Southern Space Observatory (29.42∘ S, 53.87∘ W) in São Martinho da Serra, Rio Grande do Sul. Tropospheric dynamic analysis showed a post-frontal high pressure system on 20 and 21 October 2016, with pressure levels at sea level and thickness between 1000 and 500 hPa. Horizontal wind cuts at 250 hPa and omega values at 500 hPa revealed the presence of subtropical jet streams. When these streams were allied with positive omega values at 500 hPa and a high pressure system in southern Brazil and Uruguay, the advance of the ozone-poor air mass that caused intense reductions in total ozone content could be explained. Keywords. Atmospheric composition and structure (middle atmosphere – composition and chemistry)

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.

Resumo O monitoramento de longo prazo dos eventos de Influência do Buraco de Ozônio Antártico sobre o Sul do Brasil foi realizado no período de 35 anos entre 1979 e 2013 e calculada a climatologia e anomalias dos campos estratosféricos quando de sua ocorrência. Para isso, foram analisados os dados da coluna total de ozônio (CTO) obtidos através de Espectrofotômetros Brewer, instalados no Observatório Espacial do Sul - OES/CRS/INPE - MCTIC (29,4 °S; 53,8 °O; 488,7 m) e pelos instrumentos de satélite Total Ozone Mapping Spectrometer (TOMS) e Ozone Monitoring Instrument (OMI), além de parâmetros da reanálise II do NCEP/DOE (National Centers for Environmental Prediction/ Departament of Energy) e trajetórias retroativas do modelo HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory). A metodologia empregada mostrou-se eficaz na identificação de 62 eventos com uma redução média de -9,35 ± 2,93% no conteúdo de ozônio. Além disso, foi realizada a identificação do padrão de circulação estratosférica através de campos médios e anomalias da vorticidade potencial, vento e temperatura para os dias de ocorrência do fenômeno, sendo observado um padrão de deslocamento de onda, embebida dentro de uma ampla região de circulação ciclônica, com ventos predominantemente de sul é advectado em direção ao Sul do Brasil.

Ozone plays an important role in the Earth’s atmosphere. It is mainly formed in the tropical stratosphere and is transported by the Brewer–Dobson Circulation to higher latitudes. In the stratosphere, ozone can filter the incoming solar ultraviolet radiation, thus protecting life at the surface. Although tropospheric ozone accounts for only ~10%, it is a powerful GHG and pollutant, harmful to the health of the environment and living beings. Several studies have highlighted biomass burning as a major contributor to the tropospheric ozone budget. Our study focuses on the Natal site (5.40°S, 35.40°W, Brazil), one of the oldest ozone-observing stations in Brazil, which is expected to be influenced by fire plumes in Africa and Brazil. Many studies that examined ozone trends used the total atmospheric columns of ozone, but it is important to assess ozone separately in the troposphere and the stratosphere. In this study, we have used radiosonde ozone profiles and daily TCO measurements to evaluate the variability and changes of both tropospheric and stratospheric ozone separately. The dataset in this study comprises daily total columns of colocalized ozone and weekly ozone profiles collected between 1998 and 2019. The tropospheric columns were estimated by integrating ozone profiles measured by ozone sondes up to the tropopause height. The amount of ozone in the stratosphere was then deduced by subtracting the tropospheric ozone amount from the total amount of ozone measured by the Dobson spectrometer. It was assumed that the amount of ozone in the mesosphere is negligible. This produced three distinct time series of ozone: tropospheric and stratospheric columns as well as total columns. The present study aims to apply a new decomposition method named Empirical Adaptive Wavelet Decomposition (EAWD) that is used to identify the different modes of variability present in the analyzed signal. This is achieved by summing up the most significant Intrinsic Mode Functions (IMF). The Fourier spectrum of the original signal is broken down into spectral bands that frame each IMF obtained by the Empirical Modal Decomposition (EMD). Then, the Empirical Wavelet Transform (EWT) is applied to each interval. Unlike other methods like EMD and multi-linear regression (MLR), the EAWD technique has an advantage in providing better frequency resolution and thus overcoming the phenomenon of mode-mixing, as well as detecting possible breakpoints in the trend mode. The obtained ozone datasets were analyzed using three methods: MLR, EMD, and EAWD. The EAWD algorithm exhibited the advantage of retrieving ~90% to 95% of ozone variability and detecting possible breakpoints in its trend component. Overall, the MRL and EAWD methods showed almost similar trends, a decrease in the stratosphere ozone (−1.3 ± 0.8%) and an increase in the tropospheric ozone (+4.9 ± 1.3%). This study shows the relevance of combining data to separately analyze tropospheric and stratospheric ozone variability and trends. It highlights the advantage of the EAWD algorithm in detecting modes of variability in a geophysical signal without prior knowledge of the underlying forcings.

The behavior of ozone gas (O₃) in the atmosphere varies according to the region of the globe. Its formation occurs mainly in the tropical stratosphere through the photodissociation of molecular oxygen with the aid of the incidence of ultraviolet solar radiation. Still, the highest concentrations of O₃ content are found in high-latitude regions (poles) due to the Brewer–Dobson circulation, a large-scale circulation that takes place from the tropics to the pole in the winter hemisphere. This work presents a multi-instrumental analysis at two Brazilian sites, a subtropical one (Santa Maria – 29.72° S, 53.41° W) and an equatorial one (Natal – 5.4° S, 35.4° W), to investigate ozone distributions in terms of vertical profiles (2002–2020) and total abundance in terms of total columns of ozone (1979–2020). The study is based on the use of ground-based and satellite observations. Ozone profiles over Natal, from the ground up to the mesosphere, are obtained by radiosonde experiments (0–30 km) in the framework of the SHADOZ program and by satellite measurements from the SABER instrument (15–60 km). This enabled the construction of a continuous time series for ozone, including monthly values and climatological trends. There is a good agreement between the two measurements in the common observation layer, mainly for altitudes above 20 km. Below 20 km, SABER ozone profiles showed high variability and overestimated ozone mixing ratios by over 50 %. Dynamic and photochemical effects can interfere with O₃ formation and distribution along higher latitudes through the Brewer–Dobson circulation. The measurements of the total ozone columns used are in good agreement with each other (TOMS/OMI × Dobson for Natal and TOMS/OMI × Brewer for Santa Maria) in time and space, in line with previous studies for these latitudes. Wavelet analysis was used over 42 years. The investigation revealed a significant annual cycle in both data series for both sites. The study highlighted that the quasi-biennial oscillation (QBO) plays a significant role in the variability of stratospheric ozone at the two study sites – Natal and Santa Maria. The QBO's contribution was found to be stronger at the Equator (Natal) than at the subtropics (Santa Maria). Additionally, the study showed that the 11-year solar cycle also has a significant impact on ozone variability at both locations. Given the study latitudes, the ozone variations observed at the two sites showed different patterns and amounts. Only a limited number of studies have been conducted on stratospheric ozone in South America, particularly in the region between the Equator and the subtropics. The primary aim of this work is to investigate the behavior of stratospheric ozone at various altitudes and latitudes using ground-based and satellite measurements in terms of vertical profiles and total columns of ozone.

O trabalho proposto tem como intuito avaliar as condições sinóticas durante o evento de queimadas na região amazônica no mês de agosto de 2019 o qual acabou acarretando no transporte de particulados para a região sudeste, impactando diretamente na cidade de São Paulo no dia 19 transformando o dia em noite. Para a avaliação, foi utilizado os dados de reanálise do ERA5 juntamente aos dados modelo HYSPLIT com objetivo de analisar a trajetória das parcelas de ar durante o evento. A partir das avaliações observou-se a passagem de um sistema frontal o qual teve como função a convergência de umidade e escoamento de ventos sobre a região de São Paulo favorecendo o desenvolvimento de nebulosidade. Além disso, o aumento de particulados ao longo da atmosfera pode ter contribuido como núcleo de condensação, podendo assim favorecer o aumento considerável de nuvens escuras durante o perı́odo da tarde no municı́pio impactando diretamente na radiação refletida dando um aspecto noturno para a cidade.