Comment on acp-2021-532

Abstract

This is an interesting new contribution aiming at exploring the ocean-surface mediated conversion of NO2 to HONO in the coastal marine boundary layer at two contrasting coastal locations, namely at Cape Verde (Atlantic Ocean), representative of the clean remote tropical marine boundary layer, and Weybourne (United 20 Kingdom), representative of semi-polluted Northern European coastal waters. By monitoring, among others, NO2 and HONO, it is shown that the HONO production at these two sites differs significantly from previous reports (a factor of 5 lower). As stated by these authors, these results point to significant geographical variation in the predominant HONO formation mechanisms in marine environments and indicate that caution is required when extrapolating the importance of such mechanisms from individual study locations to assess regional and/or global impacts on oxidizing capacity.