近地面层高浓度的O3会对农作物、自然生态系统造成严重的危害,采用O3通量指标能更好地评估O3对生态系统的影响.本研究采用了涡度相关法,在南京信息工程大学永丰气象站水稻生育期内进行观测,旨在研究该下垫面O3干沉降及其变化特征,以期为今后估算O3的气孔吸收和更加准确评估O3对农作物的影响提供基础.本文主要分析了O3体积分数(φ)、沉降通量(F)、沉降速率(Vd)的日变化规律并分析其与环境因子的关系,结果表明:(1)观测期间(2016年8月17日—10月10日),φ、F、Vd白天(06:30—18:30)和夜间(18:30—06:00)的均值分别为46.4 nL·L-1和25.5 nL·L-1、-369.8 ng·m-2·s-1和-131.3 ng·m-2·s-1以及0.48 cm·s-1和0.29 cm·s-1,且三者之间的变化并不同步;(2)观测点O3主要源于光化学反应,且与相对湿度(RH)、空气温度(T)、太阳辐射(SR)、摩擦风速(u*)均达到极显著相关,但φ变化相比于SR和T的变化存在一定的滞后性;(3)F日变化规律明显,曲线呈先增大后减小的单谷型;较低的RH以及较高的SR、T、u*有利于O3的沉降;一天中部分时间段内,φ对F的影响高于大气湍流交换;气孔吸收在O3沉降中起重要作用;(4)Vd的日变化分为3个阶段,呈明显的单峰变化趋势;10:30—15:30大气湍流较强(u*较大),但此时Vd却在减小,与u*的变化并不一致,说明较高的湍流强度并不总能导致较高的Vd,还要考虑其他环境条件.%The high concentration of ground-level ozone causes a serious threat to crops growth and terrestrial ecosystems, and it is better to understand ozone risk assessment based on ozone-flux index. To investigate the variational characteristics of ozone dry deposition over a rice field, the eddy-covariance method was used in Yongfeng meteorological station of Nanjing University of Information Science and Technology. This may provide a basis for estimating O3 stomatal uptake and more accurately assessing of the impact of O3 on crops. We analyzed the diurnal variations of ozone dry deposition data (including ozone concentration (φ), total deposition flux (F), and deposition rate (Vd)) and the relationships between them and main environmental factors. The results showed that: (1) During the experimental period (from August 17th to October 10th, 2016), the mean daytime (06: 30-18: 30) and nighttime values ofφ,FandVd were 46.4 nL·L-1, -369.8 ng·m-2·s-1, 0.48 cm·s-1and 25.5 nL·L-1, -131.3 ng·m-2·s-1, 0.29 cm·s-1 respectively, which was found to not mismatched between them; (2)φat the experimental site generatedmainly due to photochemical reaction. It was a significant correlation betweenφand main meteorological factors (eg. relative humidity (RH), air temperature (T), solar radiation (SR) and friction velocity (u*)) and its variation had a hysteresis compared with SR and T. (3) The daily variation ofFwas obvious and it showed a single-valley-type curve which increased first and then decreased. The lower RH and higher SR, T andu* were beneficial to ozone drydeposition. For a part of the day, the influence ofφon deposition flux was higher than atmospheric turbulence. In addition, stomatal uptake played an important role in O3dry deposition. (4) The daily variation ofVd was divided into three stages and characterized by a single-peak. During 10:30 to15:30,Vd continued to decrease when atmospheric turbulence was strong (large u*), which was not consistent with the variation ofu*. It showed that strong turbulence was not always associated with high deposition velocity, and it thus was necessary to consider other environmental factors.
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