Whole air samples were collected on board the NASA DC-8 aircraft during the NASA 2016 Student Airborne Research Program (SARP) campaign and were analyzed for a series of trace gas species using gas chromatography. Vertical profiles of each gas were examined with several gases exhibiting a great deal of spatial variability indicative of input from multiple sources at varying altitudes over the TCCON (Total Carbon Column Observing Network) site. An air mass located at 6 – 7.5 kilometers showed enhancements of marine tracers (methyl nitrate at 8.7 ± 0.44 pptv and bromoform at 0.87 ± 0.09 pptv), while the air mass above 9 kilometers had an urban source signature (i/n pentane ratio of 0.55 ± 0.02 indicative of biomass burning). Enhancements of 1,2-Dichloroethene and chloroform, 19 ± 0.95 pptv and 12 ± 0.6 pptv respectively, at 5.5 kilometers are a clear indicator of an Asian source signature. HYSPLIT back trajectories at each altitude were used to verify the origin of these enhancements. By examining marine, urban, and natural gas/oil tracers, it was determined where these air masses were prior to the TCCON site. Ethyne and carbon monoxide (CO) are both emitted from vehicle exhaust with differing atmospheric lifetimes of 2-4 weeks and two months, respectively, and can therefore be used to estimate relative air mass age. Examining each level above the boundary layer, ethyne to CO ratios were found to be less than 1, which means that every air mass is aged. Because we have an aged air mass and HYSPLIT shows sources are coming from great distances, with chemical tracers exhibiting the correct source signature, it was determined that the use of the HYSPLIT model is accurate at high altitudes.

Presentation Slides: Validating-meteorological-models-using-chemical-tracers-in-the-TCCON-spiral