Modeled nocturnal isoprene were overestimated/underestimated before/after midnight.
The overestimation was ascribed to the underestimation of wind speed.
The underestimation was mainly due to the uncertainties of NEI, 2011.
Sensitivity simulation slightly improved nocturnal isoprene predictions.
More in-situ data are required to constrain anthropogenic isoprene emissions.