The role of HONO in O3 formation and insight into its formation mechanism during the KORUS-AQ Campaign

Nitrous acid (HONO) is an important precursor of OH radicals, which is closely related to the oxidation capability of the regional atmosphere, and thus promote a lot of atmospherically chemical process, such as secondary particle formation.In the manuscript, the authors performed a field-measured HONO in Korea, and proposed that the coupling of HONO with HOx -VOCs-O3 cycle in Seoul Metropolitan Areas (SMA), and suggested that NOx, surface area, and RH were the main factors affecting ambient HONO concentrations during field-observation in this region.The topic focused by this paper is very important in the field of atmosphere chemistry.However, the measurement period is so short, and it is difficult that the present data support the conclusion.The manuscript also suffered from a couple of big flaws.