We evaluate the instantaneous ozone chemical production rates, NOx loss rates and ozone production efficiency within ozone plumes sampled on the west side of Houston,Texas, with an emphasis on days during which rapid increases (> 20 ppb/15 minutes) associated with plume passage were observed in the 15-minute average ozone mixing ratio. The production rates and efficiencies are Lagrangian chemical quantities in that they refer to chemical processes within a single parcel of air. As a result, they cannot be directly evaluated from measurements made at a fixed point that reflect the total change associated with many air parcels, each having undergone a unique history that includes many non-chemical processes (e.g., deposition, the addition of fresh emissions, etc.).

The basis for this work will be observations of key nitrogen species and VOCs measured from the top of a sky scraper in western Houston, used within a 0-dimensional model to quantify the kinetics within the sampled parcels of air. We identify the key VOCs affecting ozone production at this site, and evaluate the relative role of anthropogenic vs. biogenic VOCs. We also examine how the daily variations in ozone production and ozone production efficiencies are related to differences in VOC/NOx ratios.