ISORROPIA-Lite: A Comprehensive Atmospheric Aerosol Thermodynamics Module for Earth System Models

Aerosol simulations especially for Earth System Models require a thermodynamics module with good compromise between rigor and computational efficiency. We present evaluate ISORROPIA-lite, an accelerated simplified version of the widely used ISORROPIA-II v.2.3 aerosol model, expanded to include effects water uptake from organics updated interface communicating simulation diagnostics information. ISORROPIA-lite assumes is in metastable equilibrium (i.e., salts do not precipitate supersaturated solutions) treats Na+–NH4+–SO42––NO3––Cl––Ca2+–K+–Mg2+–Organics–H2O using binary activity coefficients precalculated look-up tables. Off-line comparison (without organic effects) more than 330,000 atmospherically-relevant states demonstrated that i) provides virtually identical results mode ii) differences stable are less 25% concentrations various semivolatile components similar modes ISORROPIA-II. Using reduced cost by 35% compared online calculation coefficients. Application PMCAMx chemical transport model 3D about 10% changes major 10%. Simulations considering did slow down but increased inorganic at nighttime. Organic could highly contribute total PM1 mass increase fine nitrate ammonium as much 1 μg m–3 places where RH levels high.