Fine‐scale study of a thick stratospheric ozone lamina at the edge of the southern subtropical barrier

Abstract

[1] A large-scale transport event resulting in a thick ozone lamina originating from midlatitudes is observed in the tropical stratosphere over Reunion island (55°E, 21°S). This isentropic transport was detected from stratospheric balloon-borne ozone measurements that showed the occurrence of the lamina and was investigated using different tools based on Ertel's potential vorticity (Epv) analyses. An original software (DYBAL) using surface coordinate and the equivalent length of Epv contours as diagnostic tools in conjunction with high-resolution outputs from an Epv advection model MIMOSA allows us to specify the origin of the lamina. The results indicate that a broad layer of stratospheric air was isentropically advected from midlatitudes across the southern edge of tropical reservoir and reached Reunion island on 12 July 2000. In addition, Eliassen-Palm's flux vectors, calculated from ECMWF analysis, show that planetary wave activity was quite large during that time period, with wave-breaking occurring around 30 km, and could have driven that exchange. In contrast with analyses of filamentation events based on model and satellite data, the present study focuses on a finescale vertical survey from in situ measurements. The filament reported in this paper is characterized by a large vertical extension and is located around the maximum of ozone concentration in the tropical stratosphere (600 K). The analysis of such events, poorly documented in the tropics, could complement satellite studies and contribute to a better determination of the transport between the tropics and the midlatitudes.

Measurements of the total ozone column using a Brewer spectrophotometer and TOMS and OMI satellite instruments over the Southern Space Observatory in Brazil

“…7 that the variability in TOC monthly anomaly over SSO is in quasi-anti-phase with the QBO modulation, and the amplitude of TOC anomaly is in the 6 DU range and in accordance with the above explanation. These results are consistent with those found in other midlatitude regions as observed in global satellite data (Randel and Wu, 1996;Yang and Tung, 1994;Baldwin, 2001) or in individual station as over the Tibetan Plateau (Zou et al, 2000) and over Lauder on New Zealand (Brinksma et al, 1998).…”

“…These results are in accordance with results obtained by Rigozo et al (2012) in a local reconstructed daily ozone time series over the south of Brazil. In other midlatitude regions, similar results were observed in SAGE II data by singular value decomposition (Randel and Wu, 1996;Fioletov at al., 2006), TOMS data by Yang and Tung (1994), MLS satellite ozone profile by wavelets analyses (Fadnavis and Beig, 2008). In addition, numerical studies in general circulation models (Chipperfield et al, 1994;Takahashi, 1999) found the ozone anomaly in midlatitude regions in approximately opposite phase in comparison with the QBO index.…”

“…The SSO geographical location is close to the dynamic barriers, and it is thus expected to show high TOC variability due to dynamic processes such as stratospheretroposphere exchanges and meridian exchanges between the stratospheric tropical reservoir and midlatitudes (Baray et al, 1999;Portafaix et al, 2003) or between the Antarctic ozone hole and midlatitudes (Kirchhoff et al, 1996).…”

Long-range transport of stratospheric aerosols in the Southern Hemisphere following the 2015 Calbuco eruption

“…The MIMOSA model can also be used to determine the origin of air masses influencing a given site, similar to an isentropic Lagrangian trajectory model. The MIMOSA model is frequently used to detect the origin of air masses inducing laminae on ozone profiles Portafaix et al, 2003).…”

“…As reported by Russell et al (1996), in addition to the prodigious increase in the stratospheric aerosol loading, this event significantly affected numerous aspects of the atmospheric system, including (i) a 2-year cooling of the global surface temperature of several tens of degrees (Canty et al, 2013;Wunderlich and Mitchell, 2017), (ii) a warming of the tropical stratosphere ranging from 1 to 4 • C (Labitzke and McCormick et al, 1992;Young et al, 1994), and (iii) a lifting of the tropical ozone layer by ∼ 1.8 km (Pueschel et al, 1992;Grant et al, 1994). Through the use of satellite and balloon-borne observations, various studies have shown that moderate volcanic eruptions (i.e., volcanic explosive index less than or equal to 4) can significantly modulate stratospheric aerosol concentrations Kravitz et al, 2010;Solomon et al, 2011;Vernier et al, 2011;Clarisse et al, 2012;Jégou et al, 2013).…”