Multiple time scale evaluation of the energy balance during the maize growing season, and a new reason for energy imbalance
Multiple time scale evaluation of the energy balance during the maize growing season, and a new reason for energy imbalance
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DOI：
10.1007/s11430-009-0002-6
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发表时间：
2009-01
期刊：
影响因子：
--
通讯作者：
Jianxia Guo;L. Bian;Yongjiu Dai
中科院分区：
文献类型：
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作者：
Jianxia Guo;L. Bian;Yongjiu Dai
能量不平衡是与使用涡流协方差法测量表面能相关的常见问题。在能量平衡评价中，人们通常更关注有效能量（显热与潜热之和）系统性低于可用能量（净辐射与地热通量之差）的统计结果。然而，当有效能量大于可用能量或它们对整体能量闭合率的贡献时，是否存在相反的情况却很少受到关注。本文通过对玉米生长季多个时间尺度的能量平衡分析，得出能量成分的不同步是逆转情况存在的主要原因。通过将有效能量分量的相位提前半小时，可以提高所有时间尺度上的能量闭合率，并在能量比超过 1 或低于 0.5 时显着减少半小时样本的数量。根据能量在多个时间尺度上的分配和转换的特点，潜热始终是能量成本的主要类型，并且能量平衡的剩余量随着玉米植株生长70天超过显热而增加。表明储热能和光合能在玉米生育期的能量平衡中发挥着重要作用。
Energy imbalance is a common problem associated with the measurement of surface energy using the eddy covariance method. In the evaluation of the energy balance, people usually pay more attention to the statistical result that the effective energy (the sum of sensible and latent heat) is systematically lower than the available energy (the difference of net radiation and ground heat flux). However, little attention has been paid to the existence of the reversed situation when the effective energy is larger than the available energy or their contribution to the overall energy closure rate. In this paper, based on the analysis of the energy balance on multiple time scales across the maize growth season, we conclude that the non-synchronization of energy components is the main reason for the existence of the reversed case. By shifting the phase of the effective energy components half an hour ahead, the rates of energy closure over all time scales are improved and dramatically reduce the number of the half-hourly samples when the energy ratio exceeds 1 or is below 0.5. According to the characteristics of the energy distribution and transformation over multiple time scales, latent heat is always the main type of energy cost, and the residual of the energy balance increases with the growth of the maize plant surpassing the sensible heat for seventy days. It is suggested that the heat storage and photosynthetic energy play an important role in the energy balance during the growing period of maize.