Regime‐Dependence of Nocturnal Nitrate Formation via N2O5 Hydrolysis and Its Implication for Mitigating Nitrate Pollution Geophysical Research Letters

The heterogeneous hydrolysis of dinitrogen pentoxide (N2O5) is an important pathway in nitrate formation; however, its formation rate and relative contribution to total particulate nitrate () are highly variable. Here we report that nocturnal formation via N2O5 hydrolysis is dependent on the regime defined by the ratio of NO2 to O3. Nocturnal formation via N2O5 hydrolysis is suppressed in an O3‐limited regime but enhanced in a NO2‐limited regime. The results have crucial implications for effective control of nitrate pollution in the future. An exclusive decrease in NO2 will decrease nocturnal formation in a NO2‐limited regime but may be less effective or even increase nocturnal formation in an O3‐limited regime.