| This study is motivated by the discrepancies found between observational data, collected in the marine boundary layer (MBL) during several large scale field campaigns, and photochemical model simulations appropriate to these campaigns. In particular, for the principal chemical species (H2O 2, CH3OOH, and HCHO) theory and measurement remain unresolved. The temporal and spatial distribution and behavior of these key species indicates they are subject to chemical and physical processes such as gas-phase chemistry, scavenging by seasalt particles, seasalt aerosol chemistry involving halogen species, air-sea gas exchange, and FT-MBL exchange. We hypothesize that the incorporation of these processes into a single model will resolve the discrepancies. A one-dimensional photochemical model is developed which contains all processes to test this concept.; A series of model simulations were conducted with varied model chemistry and material boundary flux conditions. The observational data (collected in the equatorial MBL during the PEM-Tropics (B) field program) were compared with the model results. The results indicate that two processes; (1) the FT-to-MBL O3 transport and (2) dry deposition critically influence the abundance of the key species. The results show that gas-phase chemistry alone with rationalized flux conditions is capable of capturing the behavior of CH300H and HCHO and other processes (scavenging by seasalt particles and seasalt aerosol chemistry involving halogen species) are found to be negligible under PEM-Tropics (B) conditions.; The comparisons show general agreement between the observations and theory for O3, OH, CH3OOH, HCHO, NOx, and SO2. There remain gaps in our understanding of other species such as H2O2, CH3OH, DMS, and total nitrate (HNO3 + NO3−). |
