Abstract: An eddy-covariance system combined with rapid and slow ozone concentration analyzer was used to measure ozone (O₃) dry deposition continuously in a winter wheat field in Zhengzhou. The aim of this study was to reveal the characteristics of O₃ dry deposition in winter wheat field, and to examine the influence of rainfall. The results showed that the daily average value of O₃ concentration was 42.7 nL·L^-1 during the observation period. O₃ concentration was mainly affected by solar radiation and humidity, with obvious daily and diurnal variations. The diurnal variation of O₃ flux was singlevalley type, with daily mean value of -0.0073 μmol·m^-2·s^-1 (minus sign refers the direction towards the ground), which was greatly affected by the O₃ concentration. The O₃ deposition velocity was affected by atmospheric turbulence, vegetation growth characteristics, and meteorological conditions, with daily mean value of 0.38 cm·s^-1. The diurnal variation was obvious single-peak type. The deposition velocity was mainly controlled by atmospheric dynamic process. The canopy resistance reached the daily minimum value at 9:30 a.m., which was the main factor leading to the maximum daily O₃ deposition velocity in the morning. Rainfall affected the O₃ deposition velocity of winter wheat field by increasing non-stomatal deposition and reducing atmospheric turbulence exchange. Therefore, the effects of rainfall on O₃ dry deposition were dependent on background conditions.

Key words: snowmelt water, infiltration, water balance, cylinder method.