Extended Tropospheric Chemistry (ExtTC)


Extended Tropospheric Chemistry - ExtTC

Monthly mean isoprene emissions (mg/m2/day) for July summed over all PFTs
Monthly mean SOA surface concentration (μg/m3) for July summed over all production channels.

85 species, 63 advected tracers, 243 reactions

UKCA-ExtTC is an extension to the standard chemistry increasing the number of tracers to 63 and the total number of species to 85 (37 additional tracers and 7 additional non-advected short-lived species). Emissions are taken into account for 17 of the tracers, and emissions of the four most important BVOCs (isoprene, terpenes, methanol, acetone) are now computed interactively. This process-based model can easily be extended to other species. The scheme comprises 198 reactions with 45 photolysis reactions. It includes a simple SOA sub-model consisting of 21 individual chemical and pseudo-chemical processes (e.g., gas-to-solid phase transition coefficient). The list of additional species includes isoprene, terpenes (lumped), aromatics (lumped), C4+-alkanes (lumped), ethene, propene, MEK, MVK, low-reactivity organic nitrate compounds (similar to CH3ONO2, lumped), organic acids (formic, acetic), and semi-volatile SOA precursors. This scheme is currently implemented as an extension to HadGEM2-ES.