I am not sure to understand well  "air snow boundary layer", but within atmospheric conditions, aerosols and trace gases (those who are semivolatile) tend to reach a thermodynamic equilibrium.

Given the species you mention, I think one thermodynamic model might help you, like ISORROPIA. This is a box model which takes as inputs the gas+aerosols concentrations of inorganic species H2SO4, HNO3, HCl, Na, ... and computes the partition of each one in gas/particle phase, plus particle acidity and liquid water content.

It also takes into account air temperature and relative humidity.

Hopes this helps.

@Edouard

NH3 is the key gas in ISORROPIA: it governs the equilibria

Furthermore at snow temperatures the equilibrium is at the aerosol site; you can check this yourself with the on-line model

@ Roseline

For what region? what are the concentrations of the compounds or even relative concs: ratio of SO2 / sulphate, NO2/NO3 and where is the chloride coming from and what interconversions do you think of?

@Harry

Thanks for the suggestion regarding ISORROPIA..

My study region is Polar regions (Arctic and Antarctica) where the concentration ranges from 1- 100 ng/m3 and chloride mainly comes from the surrounding sea as sea spray... as the study area is relatively pristine, free from pollution sources...

can i have your email so that i can mail you the complete details of interconversion processes at the air - snow interface

Thanks 

Regards

Roseline

I think the sulphate in the arctic is anthropogenic as shown in work with sulphur isotopes by a.o. Len Barry. In accordance with calculations of long-range transport of sulphate. Also volcanic sulphur deposits in the arctic

You can mail me via ResearchGate when you go to my page then there is a green box at the upper right-hand side

@Harry..Thanks for your response. There are various inter-conversion processes taking place at the air-snow interface. For example if I take the example of nitrogen species. NO3 in aerosols could be dry deposited on the snow surface- this could be by this conversion NO2 being converted to NO3 after getting associated with surface snow or a direct particle deposition. Further NO3 deposited on surface snow could get reactivated through this reaction: NO2/HNO3 + sea salt= NOy..The interconversion of nitrate from aerosols particles to surface snow could be affected by the presence of ions like Ca2+, Mg2+ or may be SO42-. I would like to know is there any simple box model which can take into account these reaction mechanisms and simplify the understanding of the processes at the interface? 

Hello Rosaline, I have no experience what so ever on gases and atmospheric ionic species, still since you would like to study an interface starting from data on the reservoirs in one and the other side of it, my work on modelling elemental uptake by lichens may give you some ideas since it is basically a three boxes model. Have a look at  M.A.Reis et al. "Lichen Parmelia sulcata time response model to environmental elemental availability", The Science of Total Environment, 232 (1999) 105-115. If you find it useful you have more on it on M.A.Reis et al. "Calibration of Lichen Transplants considering Faint Memory Effects", Environmental Pollution, 120 (2002) 87-95 and in my thesis, M.A.Reis, "Biomonitoring and Assessment of Atmospheric Trace Elements in Portugal – Methods Response Modelling and Nuclear Analytical Techniques", Delft University of Technology PhD Thesis, Delft University Press, Delft, The Netherlands, 2001, ISBN: 90-407-2026-6.