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

Abstract

Abstract. The behavior of ozone gas (O3) in the atmosphere varies according to the region of the globe. Its formation occurs mainly in the equatorial stratospheric layer, through the photodissociation of molecular oxygen with the aid of the incidence of ultraviolet solar radiation, but the highest concentrations of O3 content are found in regions of high latitudes (poles) through large-scale circulation (Brewer-Dobson circulation). This work presents a multi-instrumental analysis in subtropical (in Santa Maria (SM) – 29.4º S; 53.8º W) and equatorial (in Natal (NT) - 5.4º S; 35.4º W) latitudes of South America, to monitor ozone behavior using O3 vertical profile data (2002–2020) and total column ozone data (1979–2020). Comparisons between latitudes were also analyzed with data from ozonesondes, which have continuous measurements of the vertical ozone profile through the SHADOZ/NASA network, where there is a reference station in Natal. For this, 19 years of data were analyzed using SABER and SHADOZ data for NT, through the monthly average series of each instrument the monthly climatological behavior for the NT station was identified, analysis of percentage and relative differences that showed a good agreement between both instruments, mainly above 20 km altitude. It was possible to identify with the analysis in the lower stratosphere (below 20 km), the ozone content is not correctly represented by the TIMED/SABER satellite. The differences between the latitudes presented interesting analyzes regarding the O3 content in the SM and NT, through the monthly and climatological average of the SABER instrument. Dynamic and photochemical effects can interfere both with O3 formation and its distribution along higher latitudes, through the Brewer Dobson Circulation (BDC). The total column of ozone (TCO) was used, to analyze the main climatic variability that influence the two sites (SM and NT). The data analyzed here to monitor O3 in the atmosphere is available through satellite and ground-based instruments from 1979 to 2020. The instruments showed good agreement between each other (TOMS/OMI x Dobson for Natal, and TOMS/OMI x Brewer for Santa Maria) in the long-term series of O3 content measurements, in line with previous studies for these latitudes in the TCO analysis. For climate variability, wavelet analysis was used over 42 years. The investigation revealed a significant annual cycle in both data series for SM and NT. Other variability pointed out such as the Quasi-Biennial Oscillation (QBO) with significant influences in NT and less significant in SM. In addition, the solar cycle proved to be important and well established (128 months) in both site (subtropical and equatorial). The two locations presented in this work have significant importance in the behavior of ozone due to their latitudinal differences. Furthermore, few studies show this comparison between latitudes in South America using satellite and terrestrial instruments in the analysis of the behavior of O3 gas. The main motivation of this work is to show how this important trace gas behaves in the atmosphere, at different altitudes, latitudes and with different sources of influence, both for O3 vertical profile analysis with satellite data, as well as for TCO.