Attributing differences in the fate of lateral boundary ozone in aqmeii3 models to physical process representations

Abstract

Increasing emphasis has been placed on characterizing the contributions and the uncertainties of ozone imported from outside the US. In chemical transport models (CTMs), the ozone transported through lateral boundaries (referred to as LB ozone hereafter) undergoes a series of physical and chemical processes in CTMs, which are important sources of the uncertainty in estimating the impact of LB ozone on ozone levels at the surface. By implementing inert tracers for LB ozone, the study seeks to better understand how differing representations of physical processes in regional CTMs may lead to differences in the simulated LB ozone that eventually reaches the surface across the US. For all the simulations in this study (including classCombining double low line"inline-formula"WRFĝ•CMAQ, classCombining double low line"inline-formula"WRFĝ•CAMx, classCombining double low line"inline-formula"COSMO-CLMĝ•CMAQ, and classCombining double low line"inline-formula"WRFĝ•DEHM), three chemically inert tracers that generally represent the altitude ranges of the planetary boundary layer (BC1), free troposphere (BC2), and upper troposphere-lower stratosphere (BC3) are tracked to assess the simulated impact of LB specification.