3 ) is one of the most abundant anions on Earth and is found in snowpack due to continental, tropospheric, and stratospheric sources. The photolysis of nitrate releases nitrogen oxides and nitrous acid into the atmospheric boundary layer, which can alter the lifetimes of gas-phase pollutants. Additionally, the photolysis of nitrate in polar regions acts as a source of near-surface ozone and hydroxyl radicals into the atmospheric boundary layer, which then affects oxidative capacity. For these reasons, understanding nitrate reactivity is essential for advancing snow and atmospheric chemistry.