[O3 dry deposition flux observation and soil resistance modeling over a bare soil in Nanjing area in autumn].

In this study, the concentration of O3 and its deposition flux over a bare soil in Nanjing in autumn were observed by using an eddy covariance system with rapid ozone analyzer. We analyzed the correlation of ozone concentration, deposition flux, and meteorological conditions in order to explore the characteristics of the variations in ozone deposition flux and deposition velocity. We also compared flux and velocity by using modeled soil resistance with observations. The results showed that the diurnal variation of ozone concentration exhibited a single peak distribution, and it increased due to radiation enhancement from September 25th to October 28th, 2015. Ozone deposition flux over a bare soil in autumn was mainly affected by its concentration, with diurnal average values varying from -31.4 to -156.8 ng·s-1·m-2(the negative sign indicated that the deposition direction was toward the ground). As a result of non-vegetation over a bare soil, the ozone deposition flux was significantly influenced by environmental factors. Diurnal average of deposition velocities varied in the range of 0.09-0.30 cm·s-1. The turbulence exchange played a major role in the atmosphere transportation of ozone, and underlying surface condition was particularly important to O3 dry deposition over the bare soil. Soil resistance (Rs) increased exponentially with air relative humidity (RH), and the equation was Rs=89.981e0.0246RH. The parameterized ozone deposition velocities and fluxes were in good agreement with the measured values.