Report of a large depletion in the ozone layer over southern Brazil and Uruguay by using multi-instrumental data

Abstract

Abstract. Ozone is one of the chemical compounds that form part of the atmosphere. It plays a key role in the stratosphere where the “ozone layer” is located and absorbs large amounts of ultraviolet radiation. However, during austral spring (August–November), there is a massive destruction of the ozone layer, which is known as the “Antarctic ozone hole”. This phenomenon decreases ozone concentration in that region, which may affect other regions in addition to the polar one. This anomaly may also reach mid-latitudes; hence, it is called the “secondary effect of the Antarctic ozone hole”. Therefore, this study aims to identify the passage of an ozone secondary effect (OSE) event in the region of the city of Santa Maria – RS (29.68∘ S, 53.80∘ W) by means of a multi-instrumental analysis using the satellites TIMED/SABER, AURA/MLS, and OMI-ERS. Measurements were made in São Martinho da Serra/RS – Brazil (29.53∘ S, 53.85∘ W) using a sounding balloon and a Brewer Spectrophotometer. In addition, the present study aims to describe and analyse the influence that this stratospheric ozone reduction has on temperatures presented by these instruments, including data collected through the radio occultation technique. The event was first identified by the AURA/MLS satellite on 19 October 2016 over Uruguay. This reduction in ozone concentration was found by comparing the climatology for the years 1996–1998 for the state of Rio Grande do Sul, which is close to Uruguay. This event was already observed in Santa Maria/RS-Brazil on 20 October 2016 as presented by the OMI-ERS satellite and the Brewer Spectrophotometer. Moreover, a significant decrease was reported by the TIMED/SABER satellite in Uruguay. On 21 October, the poor ozone air mass was still over the region of interest, according to the OMI-ERS satellite, data from the sounding balloon launched in Santa Maria/RS-Brazil, and measurements made by the AURA/MLS satellite. Furthermore, the influence of ozone on the stratosphere temperature was observed during this period. Despite a continuous decrease detected in height, the temperature should have followed an increasing pattern in the stratospheric layer. Finally, the TIMED/SABER and OMI-ERS satellites showed that on 23 October, the air mass with low ozone concentration was moving away, and its layer, as well as the temperature, in the stratosphere was re-established. Keywords. Atmospheric composition and structure (middle atmosphere – composition and chemistry; instruments and techniques)

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

“…To exemplify the analysis developed in this paper, we present in the next section a case study that took place on 18 September 2017, as this is the most recent event identified throughout the observed period, showing a side-effect event of AOH in the region of southern Brazil. Other interesting, and even more prominent, events have already been reported by Bresciani et al (2018) and Bittencourt et al (2018).…”

“…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.…”

“…The concentration of ozone in a particular region of the Earth is mainly determined by the meridional transport of this element in the stratosphere (Gettelman et al, 2011). The explanation for the higher concentration of ozone found in polar rather than equatorial regions (where there is greater G. D. Bittencourt et al: Investigation of the behavior of the atmospheric dynamics production) is precisely a special type of poleward transport known as the Brewer-Dobson circulation, in which air masses are transported quasi-horizontally from the stratospheric tropical reservoir to polar regions (Brewer, 1949;Dobson, 1968;Bencherif et al, 2007). The poleward transport of stratospheric ozone is one of the essential factors for the concentration of this atmospheric constituent in a certain region of the planet (Ploeger et al, 2012), being much studied from the use of potential vorticity, which correlates with the transport of chemical constituent tracers such as ozone (O 3 ), nitrous oxide (N 2 O), and water vapor (H 2 O) on isentropic surfaces in the lower stratosphere.…”

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

“…Although most production takes place in the mesospheric-stratospheric equatorial region due to the higher level of solar radiation, the maximum ozone concentration is observed over the polar region (Salby, 1996). This zonal distribution is explained by the Brewer-Dobson circulation (Brewer, 1949;Dobson, 1956), which transports ozone-rich air masses from the Equator to the pole and into the stratosphere.…”

“…This phenomenon was first observed by Kirchhoff et al (1996) and reported by Pinheiro et al (2011) in South America. Recently, based on satellite and ground-based observations in Uruguay and southern Brazil, Bresciani et al (2018) showed a decrease in ozone over these sites during October 2016 due to the influence of the AOH reaching mid-latitudes. The air-mass transport in the stratosphere has been extensively analysed using the advected potential vorticity (APV), which is considered a suitable dynamical tracer in the stratosphere.…”