Can in situ formaldehyde and organic aerosol observations constrain a space-based proxy for organic aerosol abundance?

Organic aerosols are an increasingly important component of submicron aerosols as global sulfate emissions decrease. The ability to quantify global organic aerosol distributions using satellite observations would be a powerful tool for efforts to understand the links between natural and anthropogenic emissions, air quality, and climate. Both organic aerosols and formaldehyde are produced in the oxidation of biogenic and anthropogenic volatile organic compounds (VOCs). Formaldehyde, furthermore, is one of the few VOCs that can be observed globally from the space. Using in situ observations from a breadth of field campaigns (SEAC4RS, SENEX, Winter, and CalNex), we investigate the factors driving formaldehyde - organic aerosols relationships. In situ formaldehyde concentrations are found to generally correlate with organic aerosol loadings, though the relationship depends on the parameters such as the VOC sources (biogenic vs. anthropogenic), aging of air masses, and NOx levels. These results and satellite HCHO data will be used to estimate global organic aerosol loadings. The contribution of organic aerosol to total satellite aerosol optical depth may also be investigated.