A simulation of the Cerro Hudson SO2 cloud

Schoeberl, M. R.; Doiron, Scott D.; Lait, Leslie R.; Newman, Paul A.; Krueger, Arlin J.

doi:10.1029/92jd02517

Cited by 75 publications

(53 citation statements)

References 6 publications

(3 reference statements)

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“…Thus, despite the stratospheric influence of the Laki (1783) eruption, mass-independent sulfur isotope signatures in the preserved aerosols would not be expected. The situation is similar for the Mount Hudson (1991) eruption, which had an injection height of 11 to 16 km (Schoeberl et al, 1993). Again, given the high latitude of the eruption, transport processes are likely insufficient to bring the plume to a sufficient altitude for SO 2 photolysis to become a dominant process.…”

Section: Production and Preservation Of Mass-independent Sulfur Isotomentioning

confidence: 78%

SO2 photolysis as a source for sulfur mass-independent isotope signatures in stratospehric aerosols

et al. 2015

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Abstract. Signatures of sulfur isotope mass-independent fractionation (S-MIF) have been observed in stratospheric sulfate aerosols deposited in polar ice. The S-MIF signatures are thought to be associated with stratospheric photochemistry following stratospheric volcanic eruptions, but the exact mechanism responsible for the production and preservation of these signatures is debated. In order to identify the origin and the mechanism of preservation for these signatures, a series of laboratory photochemical experiments were carried out to investigate the effect of temperature and added O 2 on the S-MIF produced by two absorption band systems of SO 2 : photolysis in the 190 to 220 nm region and photoexcitation in the 250 to 350 nm region. The SO 2 photolysis (SO 2 + hν → SO+O) experiments showed S-MIF signals with large 34 S/ 32 S fractionations, which increases with decreasing temperature. The overall S-MIF pattern observed for photolysis experiments, including high 34 S/ 32 S fractionations, positive mass-independent anomalies in 33 S, and negative anomalies in 36 S, is consistent with a major contribution from optical isotopologue screening effects and data for stratospheric sulfate aerosols. In contrast, SO 2 photoexcitation produced products with positive S-MIF anomalies in both 33 S and 36 S, which is different from stratospheric sulfate aerosols. SO 2 photolysis in the presence of O 2 produced SO 3 with S-MIF signals, suggesting the transfer of the S-MIF anomalies from SO to SO 3 by the SO + O 2 + M → SO 3 + M reaction. This is supported with energy calculations of stationary points on the SO 3 potential energy surfaces, which indicate that this reaction occurs slowly on a single adiabatic surface, but that it can occur more rapidly through intersystem crossing. Based on our experimental results, we estimate a termolecular rate constant on the order of 10 −37 cm 6 molecule −2 s −1 . This rate can explain the preservation of mass independent isotope signatures in stratospheric sulfate aerosols and provides a minor, but important, oxidation pathway for stratospheric SO 2 . The production and preservation of S-MIF signals requires a high SO 2 column density to allow for optical isotopologue screening effects to occur and to generate a large enough signature that it can be preserved. In addition, the SO 2 plume must reach an altitude of around 20 to 25 km, where SO 2 photolysis becomes a dominant process. These experiments are the first step towards understanding the origin of the sulfur isotope anomalies in stratospheric sulfate aerosols.

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Section: Production and Preservation Of Mass-independent Sulfur Isotomentioning

confidence: 78%

SO2 photolysis as a source for sulfur mass-independent isotope signatures in stratospehric aerosols

et al. 2015

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“…The plume was also modelled using an isentropic trajectory model, initiated by TOMS observations of SO 2 (Schoeberl et al, 1993). These models showed good spatial agreement with observations for the first 8 days after the eruption, which is an indication that the height assignment of the erupted plume was accurate within the models.…”

Section: Case Study: Cerro Hudson Eruption In 1991mentioning

confidence: 88%

“…HIRS/2 is one of three instruments that originally constituted the Television Infrared Observation Satellite (TIrOS) Operational Vertical Sounder (TOVS), designed to provide atmospheric profile measurements of temperature and water vapour structure (Smith et al, 1979). The other TOVS instruments were the Stratospheric Sounding Unit (a radiometer) and the Microwave Sounding Unit (a scanning microwave spectrometer).…”

Section: Hirs/2 Instrumentmentioning

confidence: 99%

Retrieval of volcanic SO2 from HIRS/2 using optimal estimation

Miles¹,

Siddans²,

Grainger³

et al. 2017

Atmos. Meas. Tech.

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Abstract. We present an optimal-estimation (OE) retrieval scheme for stratospheric sulfur dioxide from the HighResolution Infrared Radiation Sounder 2 (HIRS/2) instruments on the NOAA and MetOp platforms, an infrared radiometer that has been operational since 1979. This algorithm is an improvement upon a previous method based on channel brightness temperature differences, which demonstrated the potential for monitoring volcanic SO 2 using HIRS/2. The Prata method is fast but of limited accuracy. This algorithm uses an optimal-estimation retrieval approach yielding increased accuracy for only moderate computational cost. This is principally achieved by fitting the column water vapour and accounting for its interference in the retrieval of SO 2 . A cloud and aerosol model is used to evaluate the sensitivity of the scheme to the presence of ash and water/ice cloud.

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“…At higher latitudes, the time is less, e.g. Schoeberl et al (1993a) show the SO2 plume from the Cerro Hudson (45.9 ~ S) eruption of August 1991 circled the globe in seven days.…”

Section: Volcanic Cloudmentioning

confidence: 99%

Changes in stratospheric composition, chemistry, radiation and climate caused by volcanic eruptions

Grainger¹,

Highwood

2003

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Abstract:The primary effect of a volcanic eruption is to alter the composition of the stratosphere by the direct injection of ash and gases. On average, there is a stratospherically significant volcanic eruption about every 5.5 years. The principal effect of such an eruption is the enhancement of stratospheric sulphuric acid aerosol through the oxidation and condensation of the oxidation product H2804, Following the formation of the enhanced aerosol layer, observations have shown a reduction in the amount of direct radiation reaching the ground and a concomitant increase in diffuse radiation. This is associated with an increase in stratospheric temperature and a decrease in global mean surface temperature (although the spatial pattern of temperature changes is complex). In addition, the enhanced aerosol layer increases heterogeneous processing, and this reduces the levels of active nitrogen in the lower stratosphere. This in turn gives rise to either a decrease or an increase in stratospheric ozone levels, depending on the level of chlorine loading.

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A simulation of the Cerro Hudson SO₂ cloud

Cited by 75 publications

References 6 publications

SO<sub>2</sub> photolysis as a source for sulfur mass-independent isotope signatures in stratospehric aerosols

SO<sub>2</sub> photolysis as a source for sulfur mass-independent isotope signatures in stratospehric aerosols

Retrieval of volcanic SO<sub>2</sub> from HIRS/2 using optimal estimation

Changes in stratospheric composition, chemistry, radiation and climate caused by volcanic eruptions

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A simulation of the Cerro Hudson SO2 cloud

Cited by 75 publications

References 6 publications

SO&lt;sub&gt;2&lt;/sub&gt; photolysis as a source for sulfur mass-independent isotope signatures in stratospehric aerosols

SO&lt;sub&gt;2&lt;/sub&gt; photolysis as a source for sulfur mass-independent isotope signatures in stratospehric aerosols

Retrieval of volcanic SO&lt;sub&gt;2&lt;/sub&gt; from HIRS/2 using optimal estimation

Changes in stratospheric composition, chemistry, radiation and climate caused by volcanic eruptions

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A simulation of the Cerro Hudson SO₂ cloud

SO<sub>2</sub> photolysis as a source for sulfur mass-independent isotope signatures in stratospehric aerosols

SO<sub>2</sub> photolysis as a source for sulfur mass-independent isotope signatures in stratospehric aerosols

Retrieval of volcanic SO<sub>2</sub> from HIRS/2 using optimal estimation