Abstract Title: Observational constraints on water vapor sensitivity of glyoxal to formaldehyde ratio (RGF)

Abstract Submitted to: ATMOSPHERIC SCIENCES

Abstract Text:

Glyoxal (CHOCHO) to formaldehyde (HCHO) ratio (RGF = [CHOCHO]/[HCHO])) has been suggested as a useful tool to diagnose the origin of air mases, due to their different dependence on precursor volatile organic compounds (VOCs) and NOx (NOx = NO + NO2) abundance, in their oxidational production processes. Considering the possibility of measurements from satellite for both species, this indicator likely has a significance on a regional and global scale understanding of atmospheric chemical processes, once we have enough of knowledge on the main driver in RGF factor.

However, the discrepancies on the tendency and absolute magnitude of RGF among satellite-base and ground/aircraft-based observations limit the uses of this ratio. Extensive efforts have been taken to add more constraints to reconcile these differences, in recent, mainly focused on deepening the knowledge on production of CHOCHO and HCHO aspects.

In this study, we focused on understanding the RGF from the loss mechanisms by testing the water vapor sensitivity primarily based on the KORUS-AQ 2016 (KORea and U.S.- Air Quality study, 2016) aircraft observations. Spatiotemporal distribution analysis in conjunction with 0-D box modeling work to capture the emission and meteorological impact on RGF was conducted. As a result, the aromatic VOCs (e.g., toluene, benzene, etc.) are dominating sources of CHOCHO, and the RGF ranges from 0.02 to 0.09 over Korea. We also found significant decrease in RGF at higher water vapor mixing ratio (H2O > 8000 ppmv), and these results are compared with those of other missions in the U.S. (e.g. CalNEX, SENEX, etc.). Our work highlights the implication of water mediated RGF which may alter the original signature of precursor characteristics.