An investigation into the chemistry of HONO in the marine boundary layer at Tudor Hill Marine Atmospheric Observatory in Bermuda

Abstract. Here we present measurement results of temporal distributions nitrous acid (HONO) along with several chemical and meteorological parameters during the spring late summer 2019 at Tudor Hill Marine Atmospheric Observatory in Bermuda. Large variations HONO concentration were controlled by factors including local pollutant emissions, air mass interaction island, long-range atmospheric transport precursors. In polluted plumes emitted from traffic, power plant, cruise ship nitrogen oxides (NOx) existed substantial levels (up to 278 pptv 48 ppbv, respectively), NOx-related reactions played dominant roles daytime formation HONO. The lowest was observed marine air, median concentrations ∼ 3 around solar noon < 1 nighttime. Considerably higher day low-NOx island-influenced ([NO2] ppbv), a 17 pptv. mixing ratios exhibited distinct diurnal cycles that peaked before sunrise, indicating importance photochemical processes for formation. clean contribute 21 % source, photolysis particulate nitrate (pNO3) can account missing source assuming moderate enhancement factor 29 relative gaseous nitric photolysis. contribution both pNO3 accounts only production, on surfaces such as forest canopy, might significantly production. HONO, NOx, lower when site dominated aged North American spring, reflecting effects reactive chemistry background environments.