Dispersion of oxidized sulfur from the Láscar Volcano in Dispersion of oxidized sulfur from the Láscar Volcano in connection with a subplinian eruption in April 1993 and non-connection with a subplinian eruption in April 1993 and non-

eruptive emissions in November 1989eruptive emissions in November 1989A. Amigo (1,2) and L. Gallardo(1)

1. Center for Mathematical Modeling, University of Chile, Casilla 170, Correo 3, Santiago, CHILE2. Department of Geology, University of Chile, Casilla 13518, Correo 21, Santiago, CHILE

Corresponding author: aamigo@dim.uchile.cl

IntroductionIntroduction

Modeling approachModeling approach

ConclusionsConclusions

•.

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 SUBPLINIAN ERUPTION APRIL 19-20 1993APRIL 19-20 1993

FUMAROLES FUMAROLES NOVEMBER 1989NOVEMBER 1989

ECMWFReanalysis data

(winds, temperature, etc.)0.5°horizontal resolution

43 levels from 1000 up to 20 hPa

Observed Emissions

MATCH

Robertson et al, 1999

S-SO2 S-SO4

Em

issi

ons

(95%

)

Em

issi

ons

(5%

)

Dry

dep

ositi

on

Dry

an

wet

dep

osit i

on

OH

SQcct

c

)'vc'.(-v..v

+IC; +BC

For the subplinian eruption of April 19-20 1993, the overall pattern of SOx 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 SOx 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 H2SO4

AcknowledgementsAcknowledgements: 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

MODELTOTAL DEPOSITION SOx MIXING RATIOApr 25

May 05

May 10

NEW PARTICLE FORMATION:Preliminary results from an Aerosol

Box Model (Amigo et al, 2004)

RELATIVE CONTRIBUTION:Fumarolic emissions v/sAnthropogenic emissions, represented byChuquicamata copper smelter.

Andres et al. (1991) reported SO2 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 SOx plume and the average relative contribution of both sources:

OBSERVATIONS TOMS:SO2

http://toms.umbc.edu

NOAA-11: Ash dispertion

http://www.volcano.si.edu

% p

uls

e co

ntr

ibu

tio

n

Apr 19

Apr 20

ReferencesReferences•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 SO2 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):

Svolc

Svolc+Sant

HE

IGH

T [

Km

]

SOx MIXING RATIOS

Ice coresDe Angelis et al, 2003; Ginot

et al, 2002

Illimani Tapado

6.5 km

6.0 km

5.5 km

5.0 km