Stratospheric ozone climatology and variability over a southern subtropical site: Reunion Island (21° S; 55° E)

Abstract

Abstract. The study presents the climatological characteristics of stratospheric ozone observed over Reunion Island using in-situ (ozonesonde and SAOZ) and satellite (UARS-HALOE, SAGE-II and TOMS) measurements. It uses colocalised ozonesondes (from September 1992 to February 2005) and SAOZ measurements (from January 1993 to December 2004), SAGE-II data from October 1984 to February 1999 (∼15 years), HALOE data from January 1991 to February 2005 (∼15 years), and NIMBUS/TOMS data from January 1978 to December 2004 (27 years). The satellite measurements correspond to overpasses located nearby Reunion Island (21 • S; 55 • E). The height profiles of ozone concentration obtained from ozonesonde (0.5-29.5 km) show less bias in comparison with the HALOE and SAGE-II measurements. Though, the satellite (HALOE and SAGE-II) measurements underestimate the tropospheric ozone, they are in good agreement for the heights above 15 km. The bias between the measurements and the normalized ozone profile constructed from the ozonesonde and SAGE-II satellite measurement shows that the SAGE-II measurements are more accurate than the HALOE measurements in the lower stratosphere. The monthly variation of ozone concentration derived from ozonesonde and HALOE shows a nearly annual cycle with a maximum concentration during winter/spring and minimum concentration during summer/autumn months. The time evolution of total column ozone obtained from TOMS, SAOZ and the one computed from ozonesonde and SAGE-II, exhibits similar behaviour with analogous trends as above. The TOMS variation displays a higher value of total column ozone of about 3-5 DU (10%) in comparison with the SAOZ and the integrated ozone from ozonesonde and SAGE-II.

Ozone climatology and its variability from ground based and satellite observations over Irene, South Africa (25.5º S; 28.1º E) – Part 2: Total column ozone variations

“…IASI data records a winter minimum of ~264 DU and its springtime maximum of 280 DU agrees with other satellite measurements. The result of this monthly mean ToZ agrees with earlier studies made in the Southern Hemisphere, where springtime maximum and autumn minimum ozone concentrations are expected (Sivakumar et al, 2007). It is important to note that Figure 1a shows the monthly variation of satellite measurements irrespective of the years of overpass while Figure 1b shows the ToZ variation between the combined satellite products from 1989 to 2011 and Dobson instrument over the same time period.…”

“…High ozone measurements from the TOMS satellite can also be due to the years of overpass (1978 to 1993) when atmospheric ozone concentrations were relatively high (Bojkov and Fioletov, 1995). A minimum ozone concentration of 259 DU was recorded in May (late autumn), in agreement with findings over a similar southern subtropical site, namely Reunion (Sivakumar et al, 2007). There is a systematic difference of about 2 to 3% over tropical and equatorial regions and over southern mid-latitudes in the estimate of global and zonal total ozone from GOME when compared to ground-based measurements (Fioletov et al, 2002).…”

“…Ozone measuring instrumentation aboard satellites has been used to determine global ozone concentrations for many locations (Cracknell and Varotsos, 2012). By comparison, ground-based instruments provide precise measurements at the location under study but lack the large spatial coverage given by satellites (which allow ozone measurements on a global scale) (Sivakumar et al, 2007). The availability of both ground-based and satellite measurements are of great importance to scientists as they have proved to be effective in ozone measurement analysis (Liu et al, 2013).…”

Temperature variability and trends in the UT-LS over a subtropical site: Reunion (20.8° S, 55.5° E)

“…They found a positive ozone trend (1.31±0.62 DU per decade) in the upper troposphere (10-16 km), between late 1992 and 2008. The results also covered the earlier ozone climatology reported over Reunion, based on both radiosonde/ozonesonde and Satellite data sets (Sivakumar et al, 2007). The above study is evidence of the quality of the dataset used.…”

Análise Atmosférica Dos Eventos De Efeito Secundário Do Buraco De Ozônio Antártico Sobre O Sul Do Brasil Em 2012. Parte 2:verificação Sinótica Da Troposfera Durante Os Eventos

“…Este tipo de fenômeno vem sendo frequentemente observado sobre o Sul da América do Sul (Perez e Jaque, 1998;Perez et al, 2000, Paznino et al, 2008, Sul do Brasil , Sul do continente africano (Semane et al, 2006;Sivakumar et al, 2007) e Nova Zelândia (Brinksma et al, 1998).…”