Concentrations of Glyoxal and Formaldehyde During CALNEX 2010

Atmospheric oxidation of volatile organic compounds (VOCs) via the HOx-NOx cycle can lead to elevated concentrations of tropospheric ozone and secondary organic aerosol (SOA), both of which have been shown to be detrimental to human health. A detailed and mechanistic understanding of the VOC-HOx-NOx cycle is vital for improving the predictive capabilities of models for ozone and SOA. Accurate projection of oxidized VOCs is an important aspect of validating the photochemical mechanisms in models, which can then be used to evaluate regulation strategies. Glyoxal and formaldehyde are produced though oxidation of many important VOCs, and thus are powerful tracers of photooxidation via the HOx-NOx cycle. We report measurements of glyoxal and formaldehyde in Bakersfield, California located in the San Joaquin Valley during the CALNEX 2010 campaign (May 15th through June 30th). These measurements, with relevant trends and correlations, will be presented. Glyoxal:formaldehyde ratios will also be examined during this period. This ratio has been related to the source of VOCs dominating an air mass (i.e. anthropogenic versus biogenic). Both compounds were measured in situ with both high sensitivity and high temporal resolution (30 second) via laser induced emission techniques. Glyoxal was quantified by phosphorescence (MAD-LIP instrument) and formaldehyde by fluorescence (FILIF instrument). The measurements presented herein are useful for comparisons with current atmospheric models in order to evaluate the representation of photochemical oxidation in models. Furthermore, these data are also valuable points of comparison for satellite column retrieval data.