Detection of water stress in an olive orchard with thermal remote sensing imagery
Detection of water stress in an olive orchard with thermal remote sensing imagery
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DOI：
10.1016/j.agrformet.2006.01.008
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发表时间：
2006-01
影响因子：
6.2
通讯作者：
G. Sepulcre-Cantó;P. Zarco-Tejada;J. Jiménez-Muñoz;José A. Sobrino;E. Miguel;F. Villalobos;F. Villalo
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文献类型：
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作者：
G. Sepulcre-Cantó;P. Zarco-Tejada;J. Jiménez-Muñoz;José A. Sobrino;E. Miguel;F. Villalobos;F. Villalo
研究了利用高空间分辨率遥感热成像技术检测果园等非均匀作物冠层水分胁迫的方法。机载高光谱扫描仪（AHS）在0.43-12.5μm光谱范围内以2.5m空间分辨率获取38个光谱波段的图像，进行了空降作战。2004年7月25日，在格林尼治标准时间7:30、9:30和12:30对一个橄榄园进行了三种不同的缺水灌溉处理，研究了水分胁迫下温度的空间和日变化。利用裂窗算法对热红外区域内的10个AHS波段进行评估，利用反射波段将纯冠与阴影和阳光照射下的土壤像元分离开来，用于地表温度的反演。地面真实性验证是通过放置在树木顶部的红外热传感器进行的，以连续获取热数据。利用地面传感器和AHS影像以树冠空间分辨率计算树冠温度（Tc）、树冠减去空气温度（Tc−Ta）和与灌溉良好树木的相对温差（Tc−TR，其中TRis灌溉良好树木的平均温度）。地面IRT传感器与基于机载图像的AHS估计之间的Tc - trt相关系数分别为R2=0.50 （7:30GMT）、R2=0.45 （9:30GMT）和R2=0.57 （12:30GMT）。利用机载传感器测量叶片水势与树冠Tc - tama的关系，得到的决定系数分别为R2=0.62 （7:30GMT）、R2=0.35 （9:30GMT）和R2=0.25 （12:30GMT）。全天3次获得全田Tc - ta1和Tc - tr1图像，显示了水分亏缺灌溉方案下热变率的时空分布特征。
An investigation of the detection of water stress in non-homogeneous crop canopies such as orchards using high-spatial resolution remote sensing thermal imagery is presented. An airborne campaign was conducted with the Airborne Hyperspectral Scanner (AHS) acquiring imagery in 38 spectral bands in the 0.43–12.5μm spectral range at 2.5m spatial resolution. The AHS sensor was flown at 7:30, 9:30 and 12:30GMT in 25 July 2004 over an olive orchard with three different water-deficit irrigation treatments to study the spatial and diurnal variability of temperature as a function of water stress. A total of 10 AHS bands located within the thermal-infrared region were assessed for the retrieval of the land surface temperature using the split-window algorithm, separating pure crowns from shadows and sunlit soil pixels using the reflectance bands. Ground truth validation was conducted with infrared thermal sensors placed on top of the trees for continuous thermal data acquisition. Crown temperature (Tc), crown minus air temperature (Tc−Ta), and relative temperature difference to well-irrigated trees (Tc−TR, where TRis the mean temperature of the well-irrigated trees) were calculated from the ground sensors and from the AHS imagery at the crown spatial resolution. Correlation coefficients for Tc−TRbetween ground IRT sensors and airborne image-based AHS estimations were R2=0.50 (7:30GMT), R2=0.45 (9:30GMT) and R2=0.57 (12:30GMT). Relationships between leaf water potential and crown Tc−Tameasured with the airborne sensor obtained determination coefficients of R2=0.62 (7:30GMT), R2=0.35 (9:30GMT) and R2=0.25 (12:30GMT). Images of Tc−Taand Tc−TRfor the entire field were obtained at the three times during the day of the overflight, showing the spatial and temporal distribution of the thermal variability as a function of the water deficit irrigation schemes.