1. Dispersion of oxidized sulfur from the Láscar Volcano in connection with a subplinian eruption in April 1993 and non- eruptive emissions in November 1989 Dispersion of oxidized sulfur from the Láscar Volcano in connection with a subplinian eruption in April 1993 and non- eruptive emissions in November 1989 A. Amigo (1,2) and L. Gallardo(1) 1. Center for Mathematical Modeling, University of Chile, Casilla 170, Correo 3, Santiago, CHILE 2. Department of Geology, University of Chile, Casilla 13518, Correo 21, Santiago, CHILE Corresponding author: aamigo@dim.uchile.cl Introduction Modeling approach Conclusions. The Andes are characterized by widely spread volcanism that results in high emissions of sulfur compounds in connection with both quiescent degassing and explosive events. Sulfur emitted from volcanoes play an important role in the climatic system, especially when eruptions can inject gases and aerosol precursors into the upper troposphere and stratosphere. However, these emissions are poorly constrained. In this study, using a 3-D transport and chemistry model, and analyzed meteorological fields, we assess the dispersion and deposition of oxidized sulfur emitted from the Láscar volcano (23.4ºS; 67.7ºW; 5592 m.a.s.l.) during a subplinian eruption occurred on April 19-20 1993, and in connection with fumarolic activity in November 1989. SUBPLINIAN ERUPTION APRIL 19-20 1993 FUMAROLES NOVEMBER 1989 ECMWF Reanalysis data (winds, temperature, etc.) 0.5°horizontal resolution 43 levels from 1000 up to 20 hPa Observed Emissions MATCH Robertson et al, 1999 S-SO 2 S-SO 4 Emissions (95%) Emissions (5%) Dry deposition Dry an wet deposition OH +IC; +BC For the subplinian eruption of April 19-20 1993, the overall pattern of SO x dispersion as seen in satellite images is captured by the model. Also, the simulated deposition is in accordance with observations from ice cores at the Illimani and Tapado glaciers. The fumarolic emissions of SO x are mainly transported to the east of the Andean range following the westerly winds. This sulfur appears to give rise to a significant production of new particles that may play a role in cloud processes occurring downwind from the volcano(es). Although the strength of fumarolic emissions from the Láscar volcano is comparable to the anthropogenic one in the area, their impacts differ substantially. Volcanic sulfur affects the upper troposphere and to the east of the Andean range, whereas anthropogenic sulfur affects the lower troposphere to west of the Andean range. Nucl Aitken Acc H 2 SO 4 Acknowledgements Acknowledgements: We are grateful for the support provided by the staff at the Swedish Meteorology and Hydrology Institute (SMHI), in particular Dr. M. Engardt, and Dr. A. Ekman at Stockholm University. This work was partially financed by the Center for Mathematical Modeling, University of Chile (CMM) and FONDECYT Grant 1030809. The MODEL TOTAL DEPOSITION SO x MIXING RATIO Apr 25 May 05 May 10 NEW PARTICLE FORMATION: Preliminary results from an Aerosol Box Model (Amigo et al, 2004) RELATIVE CONTRIBUTION: Fumarolic emissions v/s Anthropogenic emissions, represented by Chuquicamata copper smelter. Andres et al. (1991) reported SO 2 flux measurements from high temperature fumaroles of 2300 ± 1120 [MgSO2/day], i.e. comparable to those days’ emissions from a copper smelter in the area. Here we show the evolution of the SO x plume and the average relative contribution of both sources: OBSERVATIONS TOMS:SO 2 http://toms.umbc.edu NOAA-11: Ash dispertion http://www.volcano.si.edu % pulse contribution Apr 19 Apr 20 References Amigo, A., Gallardo, L., Ekman, A., and Engardt, M, 2004. Andean volcanoes as sources of aerosols in the upper troposphere. Manuscript in preparation. Andres, R.; Rose, W.; de Silva, P.; Gardeweg, M.; Moreno, H. 1991. Excessive sulfur dioxide emissions from Chilean Volcanoes. J. Volcanol. Geoth. Res. Vol. 46, pp. 323 – 329. Bluth, G; Rose, W.; Sprod, I.; Krueger, A. 1997. Stratospheric loading of sulfur from explosive volcanic eruptions. The Journal of Geology 105, pp. 671 – 683. De Angelis, M.; Simoes, J.; Bonnaveira, H.; Taupin, J.; Delmas, R. 2003. Volcanic eruptions recorded in the Illimani ice core (Bolivia): 1918 – 1998 and Tambora periods. Atmos. Chem. Phys., 3, pp. 1725 – 1741. Gardeweg, M., Medina, E., 1994: La erupción subpliniana del 19-20 de Abril de 1993 del volcán Láscar, N de Chile, 7° Congreso Geológico Chileno, Actas volumen I, p 299- 304. Ginot, P.; Schwikowski, M., Schotterer, U.; Stichler, W.; Gaggeler, H.; Francau, B. 2002. Potential for climate variability reconstruction from Andean glaciochemical records. Annals of Glaciology. Vol. 35, pp. 443 – 450. Robertson, L.; Langner, J.; Engardt, M. 1999. An Eulerian limited – area atmospheric transport model. J. of Applied Meteorology. Vol. 38, pp. 190–210. 0.4 Tg SO 2 were detected by TOMS spectrometers aboard Nimbus-7 and Meteor-3 satellites for two days of eruption (Bluth et al., 1997). The emissions occurred in pulses according to (Gardeweg and Medina, 1994): S volc S volc +S ant HEIGHT [Km] SO x MIXING RATIOS Ice cores De Angelis et al, 2003; Ginot et al, 2002 Illimani Tapado 6.5 km 6.0 km 5.5 km 5.0 km