A major event of Antarctic ozone hole influence in southern Brazil in October 2016: an analysis of tropospheric and stratospheric dynamics

Abstract

Abstract. 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.

Analysis of a southern sub-polar short-term ozone variation event using a millimetre-wave radiometer

“…The MWR-MLS inter-comparison at 27 km reveals a MBE of 5 %, which is consistent with the value obtained by Ohyama et al (2016). Boyd et al (2007) also carried out similar inter-comparisons between MLS and two MWRs installed in Mauna Loa, Hawaii, and Lauder, New Zealand. The differences reported for Lauder range from +7 % to 10 % between ∼ 20 and ∼ 28 km, while for Mauna Loa differences are around ∼ 3 % (Fig.…”

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

“…For this analysis, one needs to consider the previous days of the event or equatorial origin when a decrease in absolute potential vorticity occurs (Semane et al, 2006). Bittencourt et al (2018) and Bresciani et al (2018) showed the analysis of an extreme event of influence of the AOH on regions of middle latitudes through the analysis of the stratospheric dynamics with the fields of PV.…”

“…When there is an increase in the APV it can be stated that the mass of air had a polar origin, and otherwise (decrease in the APV) the air mass has an equatorial origin. As described above, the APV acts as a dynamic marker for large-scale air masses and, thus, observations are made to identify the secondary effect of AOH, where reductions in O 3 content are observed from intense to moderate (Bittencourt et al, 2018;Peres, 2016).…”

“…Because of this, the main objective of this paper is to show how atmospheric dynamics behave during the occurrence of events of influence of the Antarctic ozone hole over midlatitude regions such as southern Brazil, during a 12-year observation period. In addition, recent works (Peres et al, 2014;Bittencourt et al, 2018) show that there is a secondary influence of the ozone hole with these regions where the tropospheric dynamics behavior can influence most cases in the occurrence of these events.…”

“…Peres et al (2014) and Peres (2016) showed the effects of this secondary event on mid-latitude regions such as the southern region of Brazil, where ozone content falls over the region from August to November. Recently, Bittencourt et al (2018) reported on the second most intense event ever recorded in the southern region of Brazil. According to the latest World Meteorological Organization (WMO) reports (WMO, 2014(WMO, , 2018, there is a growth trend be-tween 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).…”