SOSAA (Model to Simulate the Concentration of Organic Vapours, Sulphuric Acid and Aerosol Particles) is a one-dimension chemical-transport model constructed to study emissions, transport, chemistry and aerosols in the planetary boundary layer in and above a forest canopy (Figure 1, from Mogensen et al.

2015). The boundary layer meteorology module is based on a one-dimensional version of SCADIS (Scalar Distribution, Sogachev et al. 2002) and the emission module is based on MEGAN (Model of Emissions of Gases and Aerosols from Nature, Guenther et al. 2006). The chemical mechanistic scheme information is mainly taken from the Master Chemical Mechanism via website: The chemical scheme accommodates great flexibility with respect to the freedom of selecting desired reactions. The aerosol module in SOSAA is based on the aerosol dynamics model UHMA, which is a sectional box model developed for studies of tropospheric new particle formation and growth in clear sky conditions (Korhonen et al. 2004). It has all basic aerosol processes, including nucleation, condensation, coagulation and deposition. The gas dry deposition model has been implemented into SOSAA to investigate the influence of the dry deposition processes on the atmosphere–biosphere gas exchange and in-canopy gas concentrations (Zhou et al., 2017a and b). For a detailed model description, please see Boy et al. (2011), Zhou et al. (2014) and Chen et al., 2021).

SOSAA is written in Fortran90 with the MPI parallel libraries. Chemistry and aerosol dynamics in each layer of the atmosphere can be calculated in parallel making it possible to increase the length of simulations and include more chemical reactions. Simulating one month with approximately 8000 chemical reactions and aerosol dynamics takes about 5 hours runtime, using 32 processor cores on a cluster computer. The performance of SOSAA has been tested against field measurements from Hyytiälä, Finland. The model has also been applied in several studies of atmospheric chemistry (Kurtén et al. 2011, Mogensen et al. 2011, Boy et al. 2013 and Smolander et al. 2014, Mogensen et al. 2015, Mogensen and Boy, 2015).

References (Publications with SOSAA simulations are highlighted with bold)

Chen, D., Xavier, C., Clusius, P., Nieminen, T., Roldin, P., Qi, X., Pichelstorfer, L., Kulmala, M., Rantala, P., Aalto, J., Sarnela, N., Kolari, P., Keronen, P., Rissanen, M.P., Taipale, D., Foreback, B., Baykara, M., Zhou, P., and Boy, M.: Modelling study of OH, NO3 and H2SO4 in 2007 - 2018 at SMEAR II, Finland: analysis of long-term trends, Environ.. Sci.: Atm., 1, 449-472, 2021,

Kalliokoski, T., Bäck, J., Boy, M., Kulmala, M., Kuusinen, N., Mäkelä, A., Minkkinen, K., Minunno. F., Paasonen, P., Peltoniemi, M., Taipale, D., Valsta, L., Vanhatalo, A., Zhou, L., Zhou, P. and Berninger, F.: Mitigation Impact of Different Harvest Scenarios of Finnish Forests That Account for Albedo, Aerosols, and Trade-Offs of Carbon Sequestration and Avoided Emissions, Frontiers in Forests and Global Change, 3, 562044, 2020,

Praplan, A. P., Tykkä, T., Chen, D., Boy, M., Taipale, D., Vakkari, V., Zhou, P., Petäjä, T., and Hellén, H.: Long-term total OH reactivity measurements in a boreal forest, Atmos. Chem. Phys., 19, 14431-14453, 2019

Zhou, P., Ganzeveld, L., Taipale, D., Rannik, Ü., Rantala, P., Rissanen, M.P., Chen, D. and Boy, M.:Boreal forest BVOC exchange: emissions versus in-canopy sinks, Atmos. Chem. Phys., 17, 14309-14332,, 2017b.

Zhou, P., Ganzeveld, L., Rannik, Ü., Zhou, L., Gierens, R., Taipale, D., Mammarella, I., and Boy, M.: Simulating ozone dry deposition at a boreal forest with a multi-layer canopy deposition model, Atmos. Chem. Phys., 17, 1361-1379,, 2017a.

Schobesberger, S., Lopez-Hilfiker, F. D., Taipale, D., Millet, D. B., D'Ambro, E. L., Rantala, P., Mammarella, I., Zhou, P., Wolfe, G. M., Lee, B. H., Boy, M. and Thornton, J. A.: High upward fluxes of formic acid from a boreal forest canopy, Geophys. Res. Lett., 43, 9342–9351, 2016.

Rannik, Ü., Zhou, L., Zhou, P., Gierens, R., Mammarella, I., Sogachev, A. and Boy, M.: Aerosol dynamics within and above forest in relation to turbulent transport and dry deposition, Atm. Chem. Phys., 16, 3145-3160, 2016.

Mogensen, D., Gierens, R., Crowley, J. N., Keronen, P., Smolander, S., Sogachev, A., Nölscher, A. C., Zhou, L., Kulmala, M., Tang, M. J., Williams, J. & Boy, M.: Simulations of atmospheric OH, O3 and NO3 reactivities within and above the boreal forest, Atmos. Chem. Phys., 15:3909-3932, 2015.

Mogensen, D. & Boy M.: Comment on “Observation and modelling of HOx radicals in a boreal forest” by Hens et al. (2014). Atmos. Chem. Phys., 15: 3109-3110, 2015.

Gierens, R. T., Laakso, L., Mogensen, D., Vakkari, V., Beukes, P., van Zyl, P., Hakola, H., Guenther, A., Pienaar, K., Boy, M.: Modelling new particle formation events in the South African Savannah, South African Journal of Science, 110(5/6), Art. Nr2013-0108, 12 pages, 2014.

Zhou L., Nieminen T., Mogensen D., Smolander S., Rusanen A., Kulmala M. & Boy M.: SOSAA— a new model to simulate the concentrations of organic vapours, sulphuric acid and aerosols inside the ABL — Part 2: Aerosol dynamics and one case study at a boreal forest site. Boreal Env. Res. 19(suppl. B): 237–256, 2014.

Smolander S., He Q., Mogensen D., Zhou L., Bäck J., Ruuskanen T., Noe S., Guenther A., Aaltonen H. Kulmala M. and Boy M.: Comparing three vegetation monoterpene emission models to measured gas concentrations with a model of meteorology, air chemistry and chemical transport. Biogeosciences Discuss. 10: 18563–18611, 2013.

Boy M., Mogensen D., Smolander S., Zhou L., Nieminen T., Paasonen P., Plass-Dülmer C., Sipilä M., Petäjä T., Mauldin, III R. L., Berresheim H. & Kulmala M.: Oxidation of SO2 by stabilized Criegee intermediate (sCI) radicals as a crucial source for atmospheric sulfuric acid concentrations. Atmos. Chem. Phys. 13: 3865–3879, 2013

Bäck, J., Aalto, J., Henriksson, M., Hakola, H., He., Q. and Boy, M.: Chemodiversity in terpene emissions at a boreal Scots pine stand, Biogeosciences, 9, 689-702, 2012.

Mogensen D., Smolander S., Sogachev A., Zhou L., Sinha V., Guenther A., Williams J., Nieminen T., Kajos M.K., Rinne J., Kulmala M. & Boy M. 2011. Modelling atmospheric OH-reactivity in a boreal forest ecosystem. Atmos. Chem. Phys. 11: 9709–9719, 2011.

Kurtén T., Zhou L., Makkonen R., Merikanto J., Räisänen P., Boy M., Richards N., Rap A., Smolander S., Sogachev A., Guenther A., Mann G.W., Carslaw K. & Kulmala M.: Large methane releases lead to strong aerosol forcing and reduced cloudiness. Atmos. Chem. Phys. 11: 6961–6969, 2011.

Boy M., Sogachev A., Lauros J., Zhou L., Guenther A. & Smolander S.: SOSA – a new model to simulate the concentrations of organic vapours and sulphuric acid inside the ABL – Part 1: Model description and initial evaluation. Atmos. Chem. Phys. 11: 43–51, 2011.

Guenther A., Karl T., Harley P., Wiedinmyer C., Palmer P.I. & Geron C. 2006. Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature). Atmos. Chem. Phys. 6: 3181–3210.

Korhonen H., Lehtinen K.E.J. & Kulmala M.: Multicomponent aerosol dynamics model UHMA: model development and validation. Atmos. Chem. Phys. 4: 757–771, 2004.

Kuhn, U., Rottenberger S., Biesenthal T., Wolf A., Schebeske G., Ciccioli P., Brancaleoni E., Frattoni M., Tavares T. M., & Kesselmeier J.: Isoprene and monoterpene emissions of Amazonian tree species during the wet season: direct and indirect investigations on controlling environmental functions. J. Geophys. Res.. 107: 8071–8084, 2002.

Sogachev, A., Menzhulin G., Heimann M., and Lloyd J.: A simple three-dimensional canopy-planetary boundary layer simulation model for scalar concentrations and fluxes, Tellus, 54B: 784–819, 2002.