Aerosol‐associated changes in tropical stratospheric ozone following the eruption of Mount Pinatubo

Abstract

The large amount of sulfuric acid aerosol formed in the stratosphere by conversion of sulfur dioxide emitted by the eruption of Mount Pinatubo (15.14°N, 120.35°E) in the Philippines around June 15, 1991, has had a pronounced effect on lower stratospheric ozone in the tropics. Measurements of stratospheric ozone in the tropics using electrochemical concentration cell (ECC) sondes before and after the eruption and the airborne UV differential absorption lidar (DIAL) system after the eruption are compared with Stratospheric Aerosol and Gas Experiment II (SAGE II) measurements from several years before the eruption and ECC sonde measurements from the year prior to the eruption to determine the resulting changes. Ozone decreases of up to 33% compared with SAGE II climatological values were found to be directly correlated with altitude regions of enhanced aerosol loading in the 16‐ to 28‐km range. A maximum partial‐column decrease of 29±9 Dobson units (DU) was found over the 16‐ to 28‐km range in September 1991 along with small increases (to 5.9±2 DU) from 28 to 31.5 km. A large decrease of ozone was also found at 4° to 8°S from May to August 1992, with a maximum decrease of 33±7 DU found above Brazzaville in July. Aerosol data from the visible channel of the advanced very high resolution radiometer (AVHRR) and the visible wavelength of the UV DIAL system were used to examine the relationship between aerosol (surface area) densities and ozone changes. The tropical stratospheric ozone changes we observed in 1991 and 1992 are likely be explained by a combination of dynamical (vertical transport) perturbations, radiative perturbations on ozone photochemistry, and heterogeneous chemistry.

An Estimation of the Radiative Effect in the Stratosphere due to the Pinatubo Aerosol

“…The tropospheric cooling and stratospheric warming due to solar radiation can be applied even when the temperature responses to the aerosol radiative heating, because the solar heating does not depend on the atmospheric conditions, except for ozone concentration, which decreases through the heterogeneous chemical reaction on the surface of the sulfate aerosol and through the vertical transport due to radiative heating perturbation (e.g., Tie et al, 1994;Grant et al, 1994). On the other hand, the result for the terrestrial radiation is valid only for the temperature used here because of its strong dependence on the local temperature.…”

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

“…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).…”

Role of the quasi‐biennial oscillation in the transport of aerosols from the tropical stratospheric reservoir to midlatitudes

“…The shape and altitude of the TSR and its gradient at the boundary are affected by the tropical winds [Trepte and Hitchman, 1992;Hitchman et al, 1994]. The circulation pattern related to the TSR has been described by the "tropical pipe" model [Plumb, 1996] The TSR was also observed and 'mvestigated by airborne lidar systems and the advanced very high resolution radiometer (AVHRR) [Grant et al, 1994;, and references there'mi. Grant et al [1996] showed, using AVHRR and ground-based lidar data, that poleward transport from the tropics to the northern higher latitudes seemed to be stronger in late 1992 than in late 1991.…”