Adjoint Description

The nonlinear relationship between inorganic aerosol precursor emissions and aerosol concentrations makes designing optimal emissions controls far from straightforward. For helpful receptor-oriented sensitivity analysis, ANISORROPIA (the AdjoiNt of ISORROPIA, an aerosol thermodynamic model) has been developed.

Independently, ANISORROPIA determines the sensitivity of fine mode aerosol concentrations to inorganic aerosol precursor concentrations. In the adjoint of a chemical transport model, it can be used to assess the relative contributions of emissions from different sources at various times and places.

Implementation in the GEOS-Chem adjoint and the adjoint of CMAQ is ongoing. In these global and regional modeling frameworks, inverse modeling with large sets of observations from satellites and ground-based measurements promises to refine emissions estimates of inorganic aerosol precursors such as ammonia and nitrogen oxides.