Analysis of the Summer 2004 ozone budget over the United States using Intercontinental Transport Experiment Ozonesonde Network Study (IONS) observations and Model of Ozone and Related Tracers (MOZART-4) simulations

We estimate the budget using the global chemistry transport Model of Ozone and Related Tracers version 4 (MOZART-4) with synthetic tracers that keep track of the ozone produced from selected NOx sources (stratosphere, lightning, anthropogenic, and biomass burning sources in Eurasia and the contiguous United States, and North American boreal fires).

This "model budget" is analyzed in conjunction with results from a "laminar identification method" (LID), a more empirical approach to extracting information about contributions from ozone transported down from the stratosphere, advection, and convection. Both methods give comparable results for the contribution from stratospheric ozone, an average over all sites of 20 ± 7% for the LID budget and of 26 ± 6% for the model budget (the standard deviation gives the variability over the IONS sites).