The flux data of winter wheat farmland ecosystem observed by eddy covariance system in the North China Plain from 2013 to 2014 were used to combine with the footprint model FSAM. The temporal and spatial distributions of footprint of winter wheat farmland ecosystem in the North China Plain were analyzed. The differences of footprint distribution in different atmospheric stratification and growing seasons were contrastively studied. The results indicated that in the predominant wind direction, the source areas of stable atmospheric stratification were larger than unstable atmospheric stratification during the growing season of winter wheat. When the wind direction was between 0°-90°, the source area of stable atmospheric stratification was about 17.8 m longer than unstable atmospheric stratification in initial growing season. The source area of stable atmospheric stratification was about 11 m longer than unstable atmospheric stratification in late growing season. The location of the maximum flux footprint in initial growing season was 15 m (stable atmospheric stratification) and 12.4 m (unstable atmospheric stratification) further away from the observing tower than late growing season, respectively. Meanwhile, the location of the maximum flux footprint in stable atmospheric stratification was 5 m (initial growing season) and 2.4 m (late growing season) further away from the observing tower than unstable atmospheric stratification, respectively. When the wind direction was non-dominant between 90°-180°, the location of the maximum flux footprint in diffe-rent growing seasons and atmospheric stratification were 67.8 and 53.4, 47.0 and 30.8 m away from the observing tower, respectively. When the wind direction was between 270°-360°, the location of the maximum flux footprint in different growing seasons and atmospheric stratification were 58.8 and 42.0, 41.1 and 33.1 m away from the observing tower, respectively. The flux information was mainly from the northeast, southwest and southeast, which accounted for 35.4%, 32.5% and 19.4% of the whole gro-wing season scale, respectively. The major changes of flux footprint in the whole gro-wing season of winter wheat were observed from 16.0 to 173.8 m in the northeast and from 14.7 to 209 m in the southwest. The flux information was all from the farmland ecosystem. The characteristics of diurnal variations of flux footprint in two typical dates were obvious. The source area changed with atmospheric stratification and wind direction. The flux information was all from farmland ecosystem at night, while little flux information was from residential area and orchard at daytime. The quantitative results of this study could provide basis for the research of flux footprint in farmland ecosystem. 利用2013—2014年涡度相关系统观测的华北平原冬小麦农田生态系统通量数据,结合通量贡献区模型FSAM,分析华北平原冬小麦农田生态系统通量贡献区的时空分布特点,对比研究不同大气稳定层结条件和生长期内通量贡献区的分布差异.结果表明: 在主风风向上,冬小麦整个生育期内大气稳定条件下的通量贡献区范围大于不稳定条件下的贡献区范围.在0°～90°主风风向上,生长初期稳定条件下通量贡献区范围比不稳定条件下大17.8 m左右,生长末期稳定条件下的通量贡献区范围比不稳定条件下大11 m左右.生长初期的通量贡献最大值点位置比生长末期距观测点位置远15 m(大气稳定条件)和12.4 m(大气不稳定条件);通量贡献最大值点在稳定条件下比不稳定条件下距观测点位置远5 m(生长初期)和2.4 m(生长末期).在非主风风向上,当风向为90°～180°时,生长初期和生长末期不同大气条件下的最大通量值分别位于距观测点的67.8、53.4和47.0、30.8 m.当风向为270°～360°时,生长初期和生长末期不同大气条件下的最大通量值位于距观测点的58.8、42和41.1、33.1 m.在整个生育期尺度上,观测塔的通量信息主要来自东北、西南和东南方向,其所占比例分别为35.4%、32.5%和19.4%.冬小麦整个生育期内通量贡献区的主要变化发生在观测点东北方向16.0～173.8 m和西南方向14.7～209 m,通量信息全部来源于农田生态系统.两个典型日期的通量贡献区日变化特征明显,通量贡献区范围随大气稳定条件和风向改变而发生变化.夜晚通量信息全部来源于农田生态系统,白天少部分通量信息来源于居民区和果园.本文的定量化结果可为农田生态系统通量贡献区的研究提供依据.

中文翻译：

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华北平原冬小麦农田生态系统通量足迹

利用涡度协方差系统观测的华北平原2013-2014年冬小麦农田生态系统通量数据，与FSAM足迹模型相结合。分析了华北平原冬小麦农田生态系统足迹的时空分布。对比研究了不同大气分层和生长季节的足迹分布差异。结果表明，在冬小麦生长季中，在主导风向上，稳定的大气分层源区大于不稳定的大气分层源区。当风向在0°-90°之间时，稳定的大气分层源区比初始生长季节的不稳定的大气分层长约17.8m。稳定的大气分层的源区比生长后期的不稳定的大气分层长约11 m。初始生长季节最大通量足迹的位置分别是距生长塔较晚生长季节更远离观测塔的15 m（稳定的大气分层）和12.4 m（不稳定的大气分层）。同时，稳定大气分层中最大通量足迹的位置分别比不稳定大气分层离观测塔更远，分别为5 m（初始生长季节）和2.4 m（晚期生长季节）。当风向在90°-180°之间不占主导地位时，不同生长期和大气分层中最大通量足迹的位置分别为67.8和53.4、47.0和30。分别距观测塔8 m。当风向在270°-360°之间时，不同生长季节和大气分层中最大通量足迹的位置分别距观测塔58.8和42.0、41.1和33.1 m。通量信息主要来自东北，西南和东南，分别占整个生长季季节规模的35.4％，32.5％和19.4％。在东北，从冬小麦的整个生长季，通量足迹的主要变化是从16.0到173.8 m，西南从14.7到209 m。通量信息全部来自农田生态系统。两个典型日期通量足迹的日变化特征是明显的。源区域随大气分层和风向而变化。晚上的通量信息全部来自农田生态系统，而白天的通量信息很少来自居民区和果园。定量研究结果可为农田生态系统通量足迹的研究提供依据。利用2013年至2014年涡度相关系统观测的华北平原冬小麦作物生态系统通量数据，结合通量贡献区模型FSAM，分析华北平原冬小麦作物生态系统通量贡献区的时空分布特点，对比研究不同大气稳定层结条件和生长态通量贡献区的分布差异。结果表明：在主风风向上，冬小麦整个生长大气稳定条件下的通量贡献区范围大于可变条件下的贡献区范围。在0°〜90°主风风向上，生长初期稳定条件下通量贡献区范围比可变条件下大17.8 m左右，生长末期稳定条件下的通量贡献区范围比可变条件下大11m左右。生长初期的通量贡献的观测点位置比生长末期距观测点位置远15 m（大气稳定条件）和12.4 m（大气不稳定条件）;通量贡献的观测点在稳定条件下比尺度条件下距观测点位置远5 m（生长初期）和2.4 m（生长末期）。在非主风风向上，当风向为90°〜180°时，生长初期和生长末期不同大气条件下的最大通量值分别位于距观测点的67.8、53.4和47.0、30.8 m。当风向为270°〜360°时，生长初期和生长末期不同大气条件下的最大通量值位于距观测点的58.8、42和41.1 ，33.1 m。在整个小麦生育期内尺度上，观测塔的通量信息主要来自东北，西南和东南方向，其所占比例分别为35.4％，32.5％和19.4％。的主要变化发生在观察点东北方向16.0〜173.8 m和西南方向14。