Seasonal estimation of evaporation and stomatal conductance over a soybean field using surface IR temperatures
Seasonal estimation of evaporation and stomatal conductance over a soybean field using surface IR temperatures
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DOI：
10.1016/0168-1923(94)05082-h
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发表时间：
1995-03
影响因子：
6.2
通讯作者：
O. Taconet;A. Olioso;M. B. Mehrez;N. Brisson
中科院分区：
文献类型：
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作者：
O. Taconet;A. Olioso;M. B. Mehrez;N. Brisson
在茂密的树冠上，红外遥感提供了有关树冠水分状况的信息。通过利用中午辐射温度对描述土壤、植被和大气之间传输的模型进行反演，可以推算出冠层蒸散量和冠层气孔导度。利用土壤水分测量的校准函数对土壤参数进行初始化。测量了植被密度和高度。有待确定的单一参数是冠层气孔导度。为了简化遥感反演，我们使用了一个简单的叶片电导参数。叶片电导只是入射太阳通量的函数，也是与中午叶片气孔导度有关的系数的函数。后一种系数是通过模型反演得到的。这种方法是利用1990年在阿维尼翁的INRA研究中心进行的大豆田间试验的数据进行评估的，该试验将亮温测量与整个作物周期中地表通量以及土壤和植被参数的测量联系起来。蒸散量和叶片气孔导度变化的评估是非常有前途的。它们与实验的季节演变有很好的相关性，只有轻微的低估(−0.5mmday−1和−0.002 m S−1)。推测的中午叶片气孔导度可能与控制气孔开度的环境因素的时间变化有关，如叶片水势和冠层内水汽压差。这是使用Olioso校准的电导的响应函数(Thèse de Doctorat，University de Montpellier，1992)完成的。它开启了将这种植物水分状况的遥感信息整合到作物生长模型中的可能性，特别是用于监测水分胁迫模块。
Over dense canopies, IR remote sensing provides information on the canopy water status. Both canopy evapotranspiration and canopy stomatal conductance can be inferred, through inversion of models describing the transfers between soil, vegetation and atmosphere using midday radiometric temperatures. Soil parameters are initialized using calibrated functions with soil moisture measurements. Vegetation density and height are measured. The single parameter which remains to be determined is the canopy stomatal conductance. To simplify the remote-sensed inversion, we use a simple parameterization of the leaf conductance. The leaf conductance is only a function of the incident solar flux and of a coefficient related to the level of midday leaf stomatal conductance. The latter coefficient is derived through model inversion. This method is evaluated using data from a field experiment over soybean, carried out in 1990 at the INRA Research Centre at Avignon, associating brightness temperature measurements with measurements of surface fluxes and soil and vegetation parameters throughout the crop cycle. The evaluation of evapotranspiration and leaf stomatal conductance changes is very promising. They show good correlations with experimental seasonal evolution and only slight underestimations (−0.5 mm day−1and −0.002 m s−1). The inferred midday leaf stomatal conductance can be related to the temporal variations of the environmental factors controlling the stomata aperture, as the leaf water potential and the in-canopy vapour pressure deficit. This is done using the response functions of conductance calibrated by Olioso (Thèse de Doctorat, Université de Montpellier, 1992). It opens the potentiality of incorporating this remote-sensed information of plant water status into crop growth modelling, particularly for monitoring the water stress module.