The hydroxyl radical (OH) is a highly reactive specie and plays a key role in the oxidative capacity of the atmosphere. The total OH reactivity, corresponding to the inverse of OH lifetime, may have a significant fraction non-attributable to commonly measured compounds. The turbulence-driven segregation of OH and its reactants can cause substantial modification of averaged reaction rates, and thus of the total OH reactivity, when compared to a perfectly mixed assumption. We study the impact of turbulent mixing on the OH reactivity with Large-Eddy Simulations from the Meso-NH model coupled on-line with a detailed chemistry mechanism in two contrasted regimes. Our findings show that the non-mixing of isoprene (resp. aldehydes) and OH leads to 30 % decrease (resp. 16 % increase) of the mean reaction rate at the top of the boundary layer and consequently to 9 % decrease (resp. 5 % increase) of the OH total reactivity in a biogenic (resp. anthropogenic) environment. Moreover, the total OH reactivity is highest inside thermals in both cases.
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