中文摘要：

利用北京密云站2007年1,4,8和10月辐射及湍流通量观测资料,分析了农林混合非均匀下垫面晴天、阴天条件下的辐射平衡、反照率及能量平衡特征。结果表明：（1）1,4,8和10月能量平衡闭合度（OLS方法）分别为82%,97%,72%和83%,总体闭合度为76%,数据质量较好;（2）晴天向上长波辐射1,4,8和10月平均值分别为279.6,381.5,430和358.7W.m-2;受农林混合下垫面变化的影响,响应短波辐射时间1月和8月分别为0.5h和1.5h,4月和10月介于两者之间;（3）随下垫面植被长势和土壤湿度的变化,反照率有明显改变,1,4,8和10月晴天平均值分别为0.183,0.143,0.133和0.139;由于非均匀下垫面通量贡献率随太阳辐射方向而变化,各月均存在日变化不对称现象。8月密云站的反照率（0.133）小于同期同纬度固城站的反照率（0.19）;（4）由于农林混合下垫面状态的变化,1,4和10月能量主要用于感热交换,8月主要用于潜热交换。阴天能量分配特征与晴天一致。

英文摘要：

Based on the radiation and fluxes data observed at Miyun station in Beijing in January,April,August,October 2007,the radiation balance,albedo and energy balance under different types of synoptic conditions including clear and cloudy days on heterogeneous underlying surface are analyzed.The results shows that：（1） The energy balanceclosure（OLS） was 82%,97%,72%and 83% in January,April,August and October,respectively.The total energy balanceclosure was 76%.These indicated that the quality were good;（2） As the changing of mixed crop-forest underlying surface,the averageof upwardlong-wave radiation were 279.6,381.5,430 and 358.7 W·m-2 on clear day,in January,April,August,October,respectively.Therespond time to short-wave radiation was 0.5 h and 1.5 h in January and August,respectively.（3） The behaviorof albedo is complex as it is predisposed by both surface moisture and vegetation condition.The monthly averaged value of albedo on clear day in January is 0.183, 0143 in April,0.133 in August,0.139 in October.The diurnal variation of albedo is asymmetrical.The albedo at Miyun station in August is lower than that at Gucheng station,which is 0.19. （4） On clear day,the components of energy balance showed standards daily cycle patterns.The primary distribution of energy is the sensible heat exchange in January,April and October,whilein August it is mainly used for latent heat exchange.Thecharacteristic of energy distribution on cloudy day is the same as that on clear day.