The Evapotranspiration and Energy Budget of an Achnatherum splendens Grassland in the Oasis-desert Ecotone in Xinjiang, China,during Summer and Autumn
The Evapotranspiration and Energy Budget of an Achnatherum splendens Grassland in the Oasis-desert Ecotone in Xinjiang, China,during Summer and Autumn
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2013
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通讯作者：
Z. Fang
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作者：
Z. Fang
利用野外气象观测资料，采用波文比法计算了新疆绿洲-荒漠交错带一个典型的芨芨草草地2010年夏秋季的蒸散量和能量平衡。（1）不同气象条件下蒸散日变化显著，晴天由于辐射强，蒸散曲线呈“高耸”型，阴天时，该线与云量和降水量的关系呈“平坦”型，雨天时，该线与云量和降水量的关系呈“偏斜”型。(2)d-1，日蒸散量峰值以0.0036 min. d-1的速度下降。与某些宽叶植物生境相比，一串蒿草地蒸散量的日波动较小。(3)净辐射（Rn）、潜热通量（LE）、感热通量（H）和土壤热通量（G）的日变化趋势基本一致，G/Rn、H/Rn和LE/Rn的日变化曲线在白天较为平缓，而在夜间则持续波动，且波动最剧烈的时刻出现在日出和日落时刻，潜热通量占净辐射的52.7%，远大于沙漠和戈壁。但比绿洲小。(4)波文比（β）的日内变化曲线呈下降趋势，下降幅度约为-2%;日变化曲线呈上升趋势，上升幅度约为4.8。下降趋势表明，在晴天，潜热活动随时间的推移而增强;上升趋势表明，感热活动随时间的推移而增强。
With the field observed meteorological data and the Bowen-ratio method,the evapotranspiration and energy balance in an Achnatherum splendens grassland in the oasis-desert ecotone in Xinjiang,China,were calculated during the summer and autumn of 2010.The results indicated that:(1) The diurnal evapotranspiration under different weather conditions varied significantly.Due to the strong radiation,the evapotranspirtion curve on the sunny days appeared as "towering" type,while the line in cloudy days manifested as "flatting" type in relation to the cloudiness and precipitation,and that in rainy days appeared as" skewing" type.(2) As the climate changes from summer to autumn,the occurring and ending time of the evapotranspiration within a day had some 1.73 min·d-1 lagging and 2.02 min·d-1 advancing,respectively,the evapotranspiration peak declined at a speed of 0.0036 min·d-1.Compared with the habitats of some plants with relatively wide leaf,the A.splendens grassland showed a smaller diurnal fluctuation of evapotranspiration.(3) The net radiation(Rn),latent heat flux(LE),sensible heat flux(H) and soil heat flux(G) had a similar diurnal changing trend.The curve of G/Rn,H/Rn and LE/Rn in daytime was smooth,however,it fluctuated continually at night,and the most violent fluctuation appeared at the time of sunrise and sunset.Latent heat accounted for 52.7% in net radiatio,which was much larger than that in desert and gobi,but smaller than that in oasis.(4) The intraday curve of β(Bowen ratio) demonstrated a downtrend by about-2%.But its daily variation curve represented slightly an upward trend by about 4.8.The downtrend indicated that the variation of latent heat activity would become stronger with time passing in the sunny days,while the upward trend showed that the intensity of the sensible heat activity would increases gradually with the date advancing from summer to autumn.