Seasonal variation of energy partitioning in irrigated lands
Seasonal variation of energy partitioning in irrigated lands
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DOI：
10.1002/hyp.5535
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发表时间：
2004-08
影响因子：
3.2
通讯作者：
Yanjun Shen;Yongqiang Zhang;A. Kondoh;C. Tang;Jianyao Chen;J. Xiao;Y. Sakura;Changming Liu;
中科院分区：
文献类型：
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作者：
Yanjun Shen;Yongqiang Zhang;A. Kondoh;C. Tang;Jianyao Chen;J. Xiao;Y. Sakura;Changming Liu;
利用波文比技术，连续三年测定了灌溉小麦和玉米田地表以上的能量平衡分量。试验于1999年12月至2001年9月在河北省栾城农业生态系统试验站（LESA）进行。本文讨论了灌溉农田能量平衡的季节过程、不同季节的Bowen比日变化规律以及叶面积指数（LAI）和土壤水分对能量平衡的影响。在3年间，净辐射Rn的变化范围为31.6 ~ 668.1 W m−2，土壤热通量G的变化范围为-12.7 ~170.9 W m−2。潜热通量LE与物候的发展也有明显的对应关系，如LAI。波文比的日变化在不同季节可分为三种典型的类型：（1）小麦型，其特征是早晨峰值较陡，然后下降，白天平均值在0.30左右，（2）玉米型，其特征是相对平缓，白天平均值β在0.20 ~ 0.25左右;（3）“冬季型”，中午附近出现高峰，白天平均β值是小麦或玉米的10倍以上。小麦和玉米在衰老季节前的叶面积指数与蒸发分数（EF）呈线性相关。与小麦相比，玉米的EF对LAI的依赖性更大。土壤水分状况对小麦的EF值无明显影响，而土壤有效水含量对小麦的Bowen值有一定的影响。版权所有© 2004 John Wiley & Sons，Ltd.
The energy balance components were measured above the surface of an irrigated wheat and maize field over three successive years using the Bowen ratio technique. The experiments were carried out at Luancheng Experimental Station of Agro‐ecosystem (LESA), Heibei, China, from December 1999 through to September 2001. The seasonal course of energy balance over an irrigated field, the diurnal Bowen ratio patterns in different seasons, and the effect of leaf‐area index (LAI) and soil moisture on the energy balance are discussed. Over 3 years, the net radiation Rn varied from 31·6 to 668 · 1 W m−2, and the soil heat flux G varied from −12 · 7 to 170 · 9 W m−2. The latent heat flux LE also shows apparent correspondence with the development of phenology, e.g. LAI. The diurnal course of the Bowen ratio in different seasons can be categorized into three typical patterns: (1) a ‘wheat pattern’, characterized by a steep morning peak followed by a decrease with the daytime mean value of around 0·30; (2) a ‘maize pattern’, which is a relatively flat course with a daytime mean β of around 0·20–0·25; and (3) a ‘winter pattern’, with a near‐noon high peak with a daytime mean β of more than 10 times that those for wheat or maize. There are linear correlations between evaporative fraction (EF) and LAI for both wheat and maize before senescence seasons. The correspondence of EF appears more dependent on LAI for maize than for wheat. The EF does not appear correlated to soil water status, whereas the Bowen ratio is affected by extractable soil water content for wheat to some extent. No correlation for maize is found. Copyright © 2004 John Wiley & Sons, Ltd.