A library of results from the GECKO-A explicit model for multiple hydrocarbons over a range of atmospheric conditions.

GECKO-A is an automated mechanism-generating system for modeling in a hyper-explicit manner the atmospheric transformations of hydrocarbons. The GECKO-A system uses mechanistic and kinetic data from laboratory measurements where available, and applies various Structure-Activity Relations (SARs) when laboratory data are not available, to estimate rate coefficients and branching ratios for thermal and photolytic chemical reactions, as well as to estimate molecular properties (e.g., saturation vapor pressure and solubility) that control partitioning of chemical species between phases. 

ACOM has recently created the GECKO-A Output Library, a resource that provides to the community GECKO-A output detailing the main gas and particle phase products generated from individual hydrocarbon precursors under relevant atmospheric conditions. Data are provided for more than 50 hydrocarbons, including alkanes, alkenes, aromatics, and biogenics, under conditions ranging from pristine remote to polluted urban. Downloadable results include yields of secondary organic aerosols (SOA), major gas- and aerosol-phase species, distributions of functional groups and product molecular masses, vapor pressures, and solubility coefficients, and van Krevelen diagrams for the oxidation pathways.  The figure below highlights output for tetradecane (a long chain hydrocarbon, C₁₄H₃₀) under an urban (high NO_x) scenario.

Figure 1. Example plots from the GECKO-A Output Library.