The Atmospherically Relevant Chemistry and Aerosol Box Model (ARCA) is used for simulating atmospheric chemistry and the time evolution of aerosol particles and the formation of stable molecular clusters. The model can be used for example in solving of the concentrations of atmo- spheric trace gases formed from some predefined precursors, simulation and design of smog chamber exper- iments or indoor air quality estimation. The backbone of ARCAs chemical library comes from Master Chemical Mechanism (MCM), extended with Peroxy Radical Autoxidation Mechanism (PRAM), and is further extendable with any new reactions. Molecular clustering is simulated with the Atmospheric Cluster Dynamics Code (ACDC). The particle size distribution is represented with two alternative methods whose size and grid density are fully configurable. The evolution of the particle size distribution due to the con- densation of low volatile organic vapours and the Brownian coagulation is simulated using established kin- etic and thermodynamic theories.
The user interface of ARCA differs considerably from the previous comparable models. The model has a graphical user interface which improves its usability and repeatability of the simulations. The user inter- face increases the potential of ARCA being used also outside the modelling community, for example in the experimental atmospheric sciences or by authorities.
ARCA is a free available computational code which can be downloaded after registration. If you are intereted in applying the model please watch the short "ARCA introduction" video next. In case you have any question concerning the model you can always conduct us under ARCA@helsinki.fi.