Snow physics as relevant to snow photochemistry

[摘要] Snow on the ground is a complex multiphase photochemical reactor thatdramatically modifies the chemical composition of the overlying atmosphere.A quantitative description of the emissions of reactive gases by snowrequires knowledge of snow physical properties. This overview details ourcurrent understanding of how those physical properties relevant to snowphotochemistry vary during snow metamorphism. Properties discussed aredensity, specific surface area, thermal conductivity, permeability, gasdiffusivity and optical properties. Inasmuch as possible, equations toparameterize these properties as functions of climatic variables areproposed, based on field measurements, laboratory experiments and theory.The potential of remote sensing methods to obtain information on some snowphysical variables such as grain size, liquid water content and snow depthare discussed. The possibilities for and difficulties of building a snowphotochemistry model by adapting current snow physics models are explored.Elaborate snow physics models already exist, and including variables ofparticular interest to snow photochemistry such as light fluxes and specificsurface area appears possible. On the other hand, understanding the natureand location of reactive molecules in snow seems to be the greatestdifficulty modelers will have to face for lack of experimental data, andprogress on this aspect will require the detailed study of natural snowsamples.

[学科分类] 大气科学