Transport of Cerro Hudson SO₂ clouds

Abstract

The Cerro Hudson volcano in southern Chile (45.92°S, 73.0°W) emitted large ash and sulfur dioxide clouds on August 12–15, following several days of minor activity [Global Volcanism Network Bulletin, 1991]. The SO2 clouds were observed using (preliminary) near real‐time data from the Total Ozone Mapping Spectrometer (TOMS) as they encircled the south polar region. The injection of SO2 into the stratosphere has essentially created a gigantic chemical tracer that could provide new insights into the wind patterns and seasonal circulation around the Antarctic region. around the Antarctic region. The TOMS instrument, on board the National Aeronautic and Space Administration's Nimbus 7 satellite, measures the ratio of backscattered Earth radiance to incoming solar irradiance in the ultraviolet spectrum. Although originally designed to measure ozone, it was later discovered that the TOMS instrument could also detect and quantify SO2 [Krueger, 1985]. After this discovery, measurements from TOMS were examined for SO2 emissions for all recorded volcanic eruptions since Nimbus‐7 was launched in October 1978, and current data are analyzed as new eruptions occur. The satellite is in a polar, Sun‐synchronous orbit so that it crosses the equator at local noon and observes the whole sunlit Earth in approximately 14 orbits each day. Total column amounts of SO2 are determined that represent the amount of gas affecting the reflection of ultraviolet light through a column of the atmosphere from the satellite to the reflecting surface, Earth, given in terms of milli atmospheres centimeter (1000 milli atm cm = a gas layer 1‐cm thick at STP). The mass of SO2 is calculated by integrating over the cloud area to obtain a volume, then converting to tons.

Volcanic sulfate deposition to Greenland and Antarctica: A modeling sensitivity study

“…Published ice core flux estimates following the eruptions of Pinatubo and Tambora (Table ) are compared to the modeled deposition flux for the 17 and 45 Tg SO 2 injection experiments at the locations of the ice cores in the left‐hand panels of Figure . It should be noted that the Pinatubo sulfate signal in Antarctic ice cores includes a component from the eruption of Cerro Hudson, which injected about 1.5 Tg of SO 2 into the atmosphere—about 10% of that of Pinatubo [ Doiron et al ., ]. Error bars on the model values represent the 2‐sigma ensemble model variability.…”

UV induced mass‐independent sulfur isotope fractionation in stratospheric volcanic sulfate

“…The near‐zero Δ 33 S (−0.09‰) of Cerro Hudson sulfate indicates that the sulfate was formed primarily through a mass dependent process. Observations during the atmospheric distribution and transport of the 1991 Cerro Hudson SO 2 clouds indicated that the eruption was a predominantly upper tropospheric/lower stratospheric (11–16 km) event [ Cacciani et al , 1993; Schoeberl et al , 1993]; the amount of sulfur emitted (1.5 Tg SO 2 ) was relatively small [ Doiron et al , 1991], with a substantial fraction of volcanic debris reaching Antarctica via the middle/upper troposphere (8–12 km) [ Deshler et al , 1992; Legrand and Wagenbach , 1999]. Volcanic SO 2 in the upper troposphere and lower polar stratosphere is not subjected to photodissociation since little high energy UV light (<220 nm) is available at this altitude, making it similar to the case of tropospheric aerosol and background sulfates.…”

A 780-year record of explosive volcanism from DT263 ice core in east Antarctica

“…Plentiful SO 2 , above 1500 Kt, produced by the Chile Hudson volcanic eruption (45°55′ S, 73°00′ W) in August 1991 is ejected into the atmosphere, and approaches 8% of 20 Mt released by Philippine Pinatubo volcano(15°08′ N，120°21′ E) in June 1991 [24] . The volcanic aerosol mass from Hudson eruption extended southward immediately due to the short distance between this volcano and Antarctica [25] , along with the relatively low altitude of particulate cloud mass.…”