密西西比地区农田下垫面能量平衡特征研究.docVIP

密西西比地区农田下垫面能量平衡特征研究 　　摘要 近些年来涡旋相关技术被广泛地应用在大陆生态平衡系统和天空大气之间二氧化碳和水汽等大气物质传动与输送和能量平衡交换的研究中。通过分析密西西比2006年6―9月的通量观测资料，分析了农田下垫面上能量收支的特征及变化规律，并运用OLS（Ordinary Least Squares）和EBR（Energy Balance Ratio）方法对湍流通量（感热与潜热通量之和）与有效能量（净辐射与土壤热通量之差）之间的关系进行了研究。结果表明：在不同天气条件下辐射平衡和能量平衡特征有很大变化。大气有效能量和湍流通量之间有很好的相关关系，但是地面湍流通量系统性低于有效能量，存在能量不闭合现象，不闭合率约为24%。在早间和午后这段时间EBR值变化最为强烈，中午前后明显大于早晚，地面能量闭合度在白天的要低于晚上。 　　关键词 农田下垫面；涡旋；能量闭合度；能量平衡；密西西比地区 　　中图分类号 P467 文献标识码 A 文章编号 1007-5739（2016）17-0163-02 　　Abstract The eddy correlation technique has been widely applied in research on transmission and exchange of energy between terrestrial ecosystems and the atmosphere and the substance. In this paper，through the analysis of flux observation data during June to September，the characteristics and changes of farmland surface energy budget components were studied，and the relationship between turbulent flux（sum of sensible and latent heat fluxes） and the effective energy（net radiation and soil heat flux difference） was studied by using OLS（Ordinary Least Squares） and EBR（Energy Balance Ratio） methods. The results showed that radiation balance and energy balance are greatly changed under different weather conditions. There is a good correlation between the effective energy and turbulent flux，but the system is less effective than the effective energy，there is no energy closure phenomenon，no-closing rate is about 24%. In the morning and evening，the EBR value is the most intense during the period of sunrise and sunset，and the characteristic of diurnal variation is obvious. Energy close degree is lower during daytime than that at night. 　　Key words farmland underlying surface；eddy；energy closure；energy balance；Mississippi region 　　大气净辐射能在内部的分配比例及规律一直是现代化农田生态学、农业气象学和水文学等学科研究的热点[1]。大气圈运动的总热能与动量平衡，主要受地面摩擦和山脉作用而发生变化。因摩擦力的方向和风向相反，在东风带里，地面摩擦力给大气一个自西向东的力矩，使地球持续地给予大气正的总热能与动量，因此近地面层的东风逐渐减弱；在西风带里，地面摩擦力给大气一个自东向西的力矩，地球持续地从大气获取正的总热能与动量。 　　经过几十年的发展，动量涡度相关法仍是当前地气交换研究中最先进和首选的地气热能与动量平衡通量观测方法，全球各地对各类生态系统大气微观元素通量进行长期观测的涡度相关通量测定站点超过5