Evaluation of Model Simulated Source Contributions to Tropospheric Ozone with Aircraft Observations on the Factor Projected Space

Trace gas measurements from TOPSE and TRACE-P experiments and the corresponding GEOS-CHEM simulations are analyzed to evaluate the simulated source contributions to tropospheric ozone. The positive matrix factorization (PMF) is applied to 7 chemicals (O3, NOy, PAN, CO, C3H8, CH3Cl, and 7Be) and one dynamic tracer (potential temperature). The evaluation has a bias towards high altitude of 5-8 km (~70 % of the data) for TOPSE and 7-12 km (40-50 % of the data) for TRACE-P due to the availability of 7Be measurements. We identify one stratospheric factor and three tropospheric factors including fossil fuel/industry, biomass burning, and meridional transport. Tagged O3 simulations are applied to quantitatively estimate the stratospheric influence of simulated O3. During TOPSE, the stratospheric factor contribution to O3 variability of 16 ppbv is much higher than the model (only 4 ppbv), indicating a large underestimation. In contrast, the stratospheric factor contribution for TRACE-P is comparable between measurements and model (8-17 ppbv and 12-14 ppbv, respectively) at mid latitudes. At low latitudes during TRACE-P (< 30°N) the model and observations are in good agreement. The stratospheric factor contribution of 8 ppbv is smaller than mid and high latitudes. The biomass burning factor contribution is more significant at 12 ppbv.