<p>Emissions from natural sources are driven by various external stimuli such as sunlight, temperature, and soil moisture. Once biogenic volatile organic compounds (BVOCs) are emitted into the atmosphere, they rapidly react with atmospheric oxidants, which has significant impacts on ozone and aerosol budgets. However, diurnal, seasonal, and interannual variability of these species are poorly captured in emissions models due to a lack of long-term, chemically speciated measurements. Therefore, increasing the monitoring of these emissions will improve the modeling of ozone and secondary organic aerosol concentrations. Using two years of speciated hourly BVOC data collected at the Virginia Forest Lab (VFL), in Fluvanna County, Virginia, we examine how minor changes in the composition of monoterpenes between seasons are found to have profound impacts on ozone and OH reactivity. The concentration of a range of BVOCs in the summer were found to have two different diurnal profiles, which we demonstrate appear to be driven by light-dependent versus -independent emissions. Factor analysis was used to separate the two observed diurnal profiles and determine the contribution from each driver. Highly reactive BVOCs were found to have a large influence on atmospheric reactivity in the summer, particularly during the daytime. These findings reveal a need to monitor species with high atmospheric reactivity but have low concentrations and to more accurately capture their emission trends in models.</p>