Meteorological influence on the seasonal and diurnal variability of the dispersion of volcanic emissions in Nicaragua: a numerical model.

Langmann, Baerbel, Hort, Matthias and Hansteen, Thor (2009) Meteorological influence on the seasonal and diurnal variability of the dispersion of volcanic emissions in Nicaragua: a numerical model. Journal of Volcanology and Geothermal Research, 182 (1/2). pp. 34-44. DOI 10.1016/j.jvolgeores.2009.01.031.

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Abstract

Nicaragua comprises seven historically active volcanoes (Cosigüina, San Cristobal, Telica, Cerro Negro, Momotombo, Masaya, and Concepcion), five of which are in a state of continuous degassing. Published measurements of the atmospheric dispersion of continuous emissions from Nicaraguan volcanoes, the chemical and aerosol microphysical modifications of the released gases and aerosols, and related acid deposition and impacts on the environment cover only short periods of time. We applied a three-dimensional atmosphere-chemistry/aerosol numerical model over Central America focussing on Nicaraguan volcanic emissions for month long simulation periods during the dry and wet seasons of 2003. The model is able to reproduce observed monthly precipitation and wind speed throughout the year 2003. Model results for near surface SO2 concentrations and SO2 dry deposition fluxes around Masaya volcano are in very good agreement with field measurements. During the dry season, oxidation of SO2 to sulphate plays only a minor role downwind of the Nicaraguan volcanoes and over the Pacific Ocean, whereas SO2 released from Arenal and Poas in Costa Rica is oxidised to sulphate much faster and closer to the volcanoes due to higher humidity and cloud water availability. During the wet season, more variable wind conditions lead to reduced dispersion of SO2 over the Pacific Ocean and increased dispersion inland. The availability of liquid water in the atmosphere favours sulphate formation close to the Nicaraguan volcanoes via aqueous phase oxidation and represents another limitation for the dispersion of SO2. Strong precipitation removes sulphate quickly from the atmosphere by wet deposition. Atmospheric SO2 concentrations and in particular dry deposition close to the volcanoes show a pronounced diurnal cycle.

Document Type: Article
Keywords: Nicaragua, continuous volcanic degassing, atmosphere-chemistry numerical modelling
Research affiliation: OceanRep > SFB 574 > C4
OceanRep > SFB 574
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.jvolgeores.2009.01.031
ISSN: 0377-0273
Projects: SFB574
Contribution Number:
ProjectNumber
SFB 574163
Expeditions/Models/Experiments:
Date Deposited: 16 Dec 2009 15:28
Last Modified: 08 Aug 2017 11:50
URI: http://oceanrep.geomar.de/id/eprint/3246

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