To study this problem, a full suite of chemical compounds must be measured (e.g NO, NO2, peroxides, formaldehyde, water vapor, ozone, CO, CH4, hydrocarbons including oxygenated species, PAN and PAN-like compounds, SO2, DMS?, halogen species?, etc), radical species (OH, HO2, RO2, halogen radicals?) characterization of the radiation field (actinic flux spectroradiometer, possibly other radiometers), aerosol size distribution and composition, and boundary layer (and perhaps stratospheric) tracers.
The flights would consist of profiles over continental and marine regions to examine the budget of HO2, OH and RO2 probably accomplished through stair-step patterns with legs long enough for accurate measurements by the slowest of the measurement techniques. We would want legs from near the surface to the aircraft ceiling, getting as close to the tropopause as possible. It would be desirable to pick a region not too impacted by recent emissions of NOx and sulfur so that interpretation would be potentially more straightforward. Modeling and ancillary measurements would be required to quantify the magnitude and frequency of convective transport of radical precursors (and the impact of cloud interactions on their abundance) to the study region. Additionally it would be interesting to examine this problem as functions of solar zenith angle, latitude and cloud cover fraction to see if the operative mechanisms change.