Detection of SO2 in the Plume of Volcán Turrialba From Ozonesonde Measurements: An Update
Abstract
Turrialba volcano is located in Costa Rica at 10.0°N, 83.8°W and 3340 m a.s.l. It had been quiescent since a series of eruptions that occurred in 1866 that were sometimes accompanied by pyroclastic flows. Fumarolic activity continued at the summit craters and has intensified since 1996; their maximum intensity was in the period from 2006 - 2007. Due to its record of explosive eruptions, location, height and meteorological factors this volcano represents a significant threat to the Central Valley and during the latter period it has greatly affected the ecological, social and economic development of the region. Vertical profiles of ozone have been made on a regular basis since July 2005 at Alajuela, Costa Rica (10°N, 84.2°W, 883.5 m a.s.l) using balloon-borne electrochemical concentration cell (ECC) ozonesondes, combined with standard radiosondes and occasionally Cryogenic Frostpoint Hygrometer. Soundings are launched one per week and typically reach 30 km altitude. Since high concentrations of SO2 interfere with the reaction between ozone and the potassium iodide solution in the ECC ozonesonde, these profiles can be used to detect volcanic activity. Between 20 December 2007 and 1 February 2008, half of the soundings showed layers below 4 km up to 1 km thick with SO2 amounts in excess of 20 ppbv. This is the highest frequency of such observations since the beginning of ozone soundings in 2005. During this period an increase in the fumarolic activity of the Turrialba volcano was observed. In addition OMI satellite SO2 data showed that its plume was moving west, in the direction of the launch site at Alajuela. During 2008 tropospheric ozone concentrations increased again, and the fumarolic activity at the volcano appears to have diminished in intensity. Taken together, these observations suggest a significant decline in the levels of SO2.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2009
- Bibcode:
- 2009AGUSM.A31A..04B
- Keywords:
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- 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- 0370 Volcanic effects (8409)