淮河流域旱涝易发区农田的陆气相互作用——CO_2通量、能量交换和水汽输送的季节变化特征

利用淮河流域旱涝易发区的安徽省寿县农田下垫面陆气相互作用观测试验资料,重点分析观测期内CO2通量、能量交换和水汽输送的季节变化,并讨论了与此有关的辐射分量通量、下垫面反射率、波恩比、能量闭合守恒、土壤温度和土壤湿度的季节变化。结果表明:CO2通量、能量分配受地表农作物长势影响明显,其中,水稻灌浆、成熟期,被稻田吸收的CO2通量最大可超过2 mg.m-2.s-1,潜热通量达到正的极大值。稻田光合作用最旺盛时期吸收的CO2通量和释放的潜热通量均大于小麦田光合作用最旺盛时期的对应量。较大土壤热通量对应于较低的土壤水含量。试验观测期的下垫面平均反射率为0.14。作物生长期,稻田表面潜热是下垫面吸收能量的主要消费者,小麦田表面潜热和感热相当。能量闭合率ε的变化范围为0.4~1。

Seasonal variations of CO_2 flux,energy exchange and water vapor transfer over a cropland in Huaihe River Basin,China

The data get from the Sino-Japanese co-operational experiment on interaction processes between atmosphere-land surface at Shouxian in the Huaihe River Basin in China are used to analysis seasonal variations of energy,water vapor and CO_2 fluxes over a cropland.The seasonal variations of radiation components,sufrace albedo,Bowen ratio,energy balance closure,soil temperature,and soil wetness are also examined.Results show that CO_2 flux and energy partitioning are influenced by crop growth,both of rice paddy and wheat field are the sink of CO_2,and the maximum CO_2 flux absorbed by rice paddy exceeded 2 mg m~(-2)s~(-1).The energy absorbed by rice paddy mainly consumed through latent heat release.Comparison of rice growth period and wheat growth shows that rice paddy absorbed more CO_2 and released more latent heat fluxes than wheat field when photosynthesis was significant.Higher soil heat flux correspond to lower soil water content.The mean albedo was 0.14 during our experimental period.The energy budget closure systematically was less than 1,ranging from 0.4 to 1.