基于微气象学方法的麦田CO2和O3通量的观测与模拟

利用涡度相关技术对长江三角洲地区冬小麦麦田白天时段CO₂和O₃通量进行连续观测，分析其变化特征.引入并参数化Jarvis乘法模型，预测冬小麦冠层尺度CO₂和O₃通量.结果表明：整个观测期间，麦田CO₂浓度和通量的范围分别为372.3~487.1μL/L和-0.4~-40.3μmol/（m²·s），均值分别为402.6μL/L和-13.4μmol/（m²·s）.O₃浓度和通量的范围分别为4.6~116.6nL/L和-0.2~-20.7nmol/（m²·s），均值分别为50.9nL/L和-6.8nmol/（m²·s）.CO₂和O₃通量最高值出现在冬小麦的孕穗期和开花期，该时期冬小麦光合能力最强，对CO₂与O₃的吸收最大.冬小麦CO₂和O₃通量总体上呈相似的日变化模式，上午CO₂通量明显高于下午，上午O₃通量却低于下午.温度、水汽压差、光合有效辐射、物候期等环境因子驱动下的冬小麦冠层通量与叶片气孔导度具有相似的限制机制，利用修订后的Jarvis乘法模型模拟了CO₂和O₃通量，并与实测值进行对比验证，表明修订后的模型分别解释了CO₂和O₃通量62%和60%的变异性，适用于本地冬小麦CO₂和O₃通量的模拟.

Observation and simulation of CO2 and O3 fluxes in the winter wheat fieldbased on micrometeorological method

Contionous observations of CO₂ and O₃ fluxes in the winter wheat field in the Yangtze River Delta during the daytime were carried out usingthe eddy covariance technique. We analyzed the variation characteristics of CO₂ and O₃ concentrations, and fluxes during the growing season of winter wheat. Flux models for CO₂ and O₃ were employed and parameterizedto predict CO₂ and O₃ fluxes of winter wheat canopy. Canopy CO₂ concentrations and fluxesduring the whole observation period were 372.3~487.1μL/Land -0.4~-40.3μmol/(m²·s)with mean values of 402.6μL/Land -13.4μmol/(m²·s), respectively. Canopy O₃ concentrations and fluxes were 4.6~116.6nL/Land -0.2~-20.7nmol/(m²·s)with mean values of 50.9nL/Land -6.8nmol/(m²·s), respectively. The highest CO₂ and O₃ fluxes were observed in the booting stage and the flowering stage of winter wheat. The photosynthetic capacity of winter wheat was the strongest in these two stages. Therefore, the CO₂ and O₃ were most absorbed by winter wheat.As a whole the CO₂ and O₃ fluxes of winter wheat showed similar daily variation patterns. TheCO₂ flux was significantly higher in the morning than in the afternoon, while the O₃ flux was significantly lower in the morning than in the afternoon. The canopy fluxes andleaf stomatal conductance of winter wheat driven by environmental factors such as temperature, vapor pressure deficit, light intensity, and phonological period showed similar limiting mechanisms. The modified Jarvis multiplication model was used to simulate the CO₂ and O₃ fluxes, which were compared with the measured CO₂ and O₃ fluxes. It showed that approximately 62% and 60% variations of CO₂ and O₃ fluxes, respectively, could be explained bythe modified flux models, whichapplied to the simulation of CO₂ and O₃ fluxes of winter wheat.