EOF Analysis of Tropical Tropospheric Ozone in a Chemical Reanalysis

EOF analysis is a mathematical technique that may be used to identify dominant modes of variability in atmospheric data. These modes of variability are considered to be real if the spatial and time patterns identified can be linked to known atmospheric processes. Tropospheric ozone concentrations are known to vary as a result of both dynamical and chemical processes. ENSO-induced variability in tropical tropospheric ozone has been found in both satellite observations and model simulations, with those using EOF analysis reporting the first EOF and principal component time series to be highly correlated with ENSO. Another source of variability in tropospheric ozone concentration is biomass burning. In this study, EOF analysis is applied to monthly mean tropospheric ozone columns calculated from the Real-time Air Quality Modeling System (RAQMS) Aura chemical re-analysis. Investigation is made into the physical processes leading to the first three leading modes of variability identified by the EOF analysis.