Application of a cloud model in simulation of atmospheric sulfate transport and redistribution Part I. Model description

IDŐJÁRÁS

Quarterly Journal of the Hungarian Meteorological Service

Vol. 107, No. 2, April–June 2003, pp. 85–114

Application of a cloud model in simulation

of atmospheric sulfate transport and redistribution

Part I. Model description

Vlado Spiridonov¹ and Mladjen Ćurić²

¹Institute of Physics, Faculty of Natural Sciences and Mathematics,

St. Cyril and Methodius University,

Branislav Nusic 11-1/17, 1000 Skopje, Macedonia

E-mail: [e-mail]
²Department of Meteorology, Faculty of Physics, University of Belgrade,

11000 Belgrade, P.O. Box 550, Yugoslavia

E-mail: [e-mail]
(Manuscript received December 7, 2001; in final form September 25, 2002)

Abstract–The authors have incorporated the sulfur chemistry in a rather sophisticated three-dimensional compressible meso-scale cloud model with a standard bulk parameterization of microphysics. The governing equations of the model include momentum conservation equations, thermodynamic and pressure equations, four continuity equations for the various water substances, and the subgrid scale (SGS) turbulent kinetic energy equation (TKE). The chemical part is formulated in terms of the continuity equations in the gaseous, aqueous, and ice phases within the cloud. The absorption of a gas phase chemical species in the cloud water and rainwater is determined either by the equilibrium according to Henry’s law or by mass transfer limitation calculations in order to include the possible non-equilibrium states. After dissolution into cloud water and rain, follows the transfer of a soluble compound through the microphysical processes that affect the parent hydrometeor. All dissolved compounds are retained during the conversion of liquid drops to frozen hydrometeors. Melting of ice, snow, or hail again totally transfers the dissolved matter to cloud water and rain. During sublimation of hail and snow, dissolved scalar is retained in the hail or snow, unless all hydrometeor mass is converted to gas phase. The calculation of the cloud water pH and rainwater pH is based on the equilibrium hydrogen ion concentration for [H⁺], which is given by the simple charge balance equation.

Part I of the paper gives the detailed description of the model including the chemistry. Results of case studies with the model are described in Part II of the present article, which will be published in a later issue of this journal.

Key-words: scavenging, oxidation, sulfate transport, redistribution, wet deposition.