Sensitivity to grid resolution in the ability of a chemical transport model to simulate observed oxidant chemistry under high-isoprene conditions

摘要: Abstract. Formation of ozone and organic aerosol in continental atmospheres depends on whether isoprene emitted by vegetation is oxidized the high-NOx pathway (where peroxy radicals react with NO) or low-NOx pathways alternate channels, mostly HO2). We used mixed layer observations from SEAC4RS aircraft campaign over Southeast US to test ability GEOS-Chem chemical transport model at different grid resolutions (0.25°  ×  0.3125°, 2°  ×  2.5°, 4°  ×  5°) simulate this chemistry under high-isoprene, variable-NOx conditions. Observations NOx show a negative correlation, reflecting spatial segregation emissions; correlation captured 0.25°  ×  0.3125° resolution but not coarser resolutions. As result, less oxidation takes place (54 %) than (59 %). The cumulative probability distribution functions (CDFs) NOx, isoprene, concentrations little difference across good agreement observations, while formaldehyde overestimated coarse because excessive high yield. simulated observed concentration variances implies that smaller-scale non-linearities (urban power plant plumes) are important regional scale. Correlations vs. do improve finer modes variability intrinsically more difficult capture. Higher leads decreased conversion nitrates increased nitric acid, total reactive nitrogen oxides (NOy) changing Model lower free troposphere also insensitive resolution. overall low sensitivity modeled adequate when modeling boundary for global applications.