【摘 要】
：
Rice-wheat(R-W)rotation systems are ubiquitous in South and East Asia,which play an important role in modulating weather and climate.Long-term,continuous fluxmeasurements help better understand the se
【机 构】
：
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry,Institute of At
【出 处】
：
第21届中国大气环境科学与技术大会暨中国环境科学学会大气环境分会2015年学术年会
论文部分内容阅读
Rice-wheat(R-W)rotation systems are ubiquitous in South and East Asia,which play an important role in modulating weather and climate.Long-term,continuous fluxmeasurements help better understand the seasonal and inter-annual variations of the surfaceenergy and water budget over R-W rotation systems.In this study,we analyzed energypartitioning using eddy-covariance systems,net radiometers and soil heat flux plates as well asmeteorological variables over a R-W rotation system in North China Plain from 2007 to 2010.Results show that the latent heat flux(LE)consists of 77%and 89%of the surface availableenergy in the winter wheat growing season and in the rice growing season,respectively.Ascanopies developed,a gradual shift in turbulent fluxes occurred with decreasing sensible heat flux(H)and increasing LE,especially in summer rice.In conversely,during both of the maturingstages and intercropping stages,H gradually increased with LE decreasing.The opposite seasonalpatterns of the LE and H fraction resulted in significant seasonal changes in Bowen ratio(β).β insummer rice paddy(0.13-0.16)was lower than in winter wheat field(0.27-0.36).Interannualvariation of β was controlled by precipitation.These variations in magnitude and partitioning ofturbulence fluxes and available energy translated into a pronounced energy imbalance for winterwheat and summer rice,the imbalance closure ratio increased as the crop developed may due todifferences in characteristic of turbulent fluxes,such as friction velocities(u*)of mean 0.169 and0.115 m s-1 for winter wheat and summer rice.The lower energy balance closure at the early stagesof flooded rice paddy is due to the percentage of residual energy is associated with the highermount of soil water content,indicating that the mount of remained energy was stored in the waterlayer.
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