The Use of Ambient Measurements To Identify which Precursor Species Limit Aerosol Nitrate Formation.

A thermodynamic equilibrium model was used to investigate the response of aerosol NO to changes in concentrations of HNO, NH, and HSO. Over a range of temperatures and relative humidities (RHs), two parameters provided sufficient information for indicating the qualitative response of aerosol NO. The first was the excess of aerosol NH plus gas-phase NH over the sum of HNO, particulate NO, and particulate SO concentrations.