麦田O3干沉降过程及不同沉降通道分配的模拟

Simulating and partitioning ozone flux in winter wheat field: the Surfatm-O_3 model

利用涡度相关系统对南京地区冬小麦田和裸土期O_3干沉降过程进行观测的基础上,引入Surfatm-O_3干沉降模型,对其叶片气孔阻力(R_s^(leaf))、土壤阻力(R_(soil))和表面阻力(R_(cut))的公式进行参数化修订和验证,开展了冬小麦主要生育期的总O_3通量(F_(O3))、干沉降速率(V_d)及其不同沉降通道分配的模拟,并间接分析了土壤排放的NO与O_3的化学反应对O_3干沉降过程的影响.结果表明:冬小麦田FO_3和V_d的实测值与模拟值趋势相似,平均实测和模拟V_d值分别为0.39和0.37cm/s,模拟值比实测值低估5.3%,其中每一个独立阻力公式的模拟效果均较好.平均非气孔沉降(表面沉降和土壤沉降)是O_3干沉降主要的沉降通道,占总O_3通量的68.8%,表面沉降占非气孔沉降的46.7%;平均绿叶和黄叶气孔沉降分别占总O_3通量的28.6%和2.6%.白天非气孔沉降比例减小至占总O_3通量的58.8%,绿叶和黄叶的气孔沉降比例比值增大,分别占总O_3通量的37.7%和3.5%.夜晚表面沉降和土壤沉降分别占总O_3通量的64.3%和35.7%.土壤排放的NO会与O_3产生化学反应,对O_3干沉降过程产生影响,需要在今后的O_3干沉降模型中考虑.

Terrestrial ecosystems are not only the major sink for ozone,but also a critical control of surface-level ozone budget.However,due to its deleterious effects,plant functioning is affected by the ozone absorbed.It is thus very necessary to predict total ozone deposition to ecosystems and partition the different deposition pathways(stomatal pathway and non-stomatal pathway).Based on observations of the ozone dry deposition of winter wheat and bare-soil field in Nanjing by the eddy-correlation system,the Surfatm-O3 dry deposition model were added in order to modify and validate parameters of the leaf stomatal resistance(Rs leaf),soil resistance(Rsoil)and cuticular resistance(Rcut).Then the simulations of the total ozone flux(FO3)of main growth stages in Winter Wheat,dry deposition velocity(Vd)and their distributions of different deposition pathways were carried out,and the impacts of chemical reactions between NO from the soil and ozone on the ozone dry deposition process were also analyzed indirectly.The results showed the simulations and measurements of FO3 and Vd had the similar trend,and the average values of measured Vd and modelled Vd were 0.39 and 0.37cm/s,respectively.Compared with measurements,the simulations underestimated by 5.3%.The average non-stomatal deposition pathway(cuticular deposition and soil deposition)is the main pathway of ozone dry deposition,accounting for 68.8%of the total ozone flux,in which cuticular deposition was accounted for 46.7%of non-stomatal deposition.The average green and yellow leaf stomatal deposition accounted for 28.6%and 2.6%of the total ozone flux respectively.During the daytime,the proportion of non-stomatal deposition decreased to 58.8%,and the ratios of green and yellow leaf stomatal deposition increased,accounting for 37.7%and 3.5%of the total ozone flux,respectively.During the nighttime,cuticular deposition and soil deposition accounted for 64.3%and 35.7%of total ozone flux,respectively.The soil NO emission affected the dry ozone deposition process by ozone chemical reaction,which should be considered in the future ozone dry deposition model.