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首页> 外文会议>Conference on ecosystems' dynamics, agricultural remote sensing and modeling, and site-specific agriculture >Concurrent measurements of directional reflectance and temperature of a wintertime coniferous forest from space
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Concurrent measurements of directional reflectance and temperature of a wintertime coniferous forest from space

机译：从空间的冬季针叶林的定向反射率和温度的同时测量

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We measure directional reflectance and daytime temperature of a wintertime coniferous forest from space using data acquired by the Department of Energy's Multispectral Thermal Imager (MTI). The study site is the Howland experimental forest in central Maine. The data include measurements from all seasons over a one-year period from 2001-2002 but with a concentration in late winter and early spring. The results show variation in both reflectance and temperature with direction and season. The reflectance results compare favorably with previous bidirectional measurements performed at the Howland site. Near-nadir reflectance in the visible bands varies periodically over the year with a high in summer and a low in winter. Near-infrared (NIR) reflectance shows dual variation. The canopy reflectance varies as a function of solar and satellite zenith angle, presumably due to a changing proportion of shadows. Furthermore, a NIR pseudo-BRDF (bidirectional reflectance distribution function) shows that the canopy brightens in the NIR during fall and winter. Retrieved canopy temperatures are consistently warmer in the off-nadir view by about 2°C, with a small seasonal variation. The seasonal canopy temperature trend is well exhibited, and days with snow on the ground are easily distinguished from days with no snow on the ground. The results also show that the retrieved temperatures are consistently warmer than above-canopy air temperature by about 4°C. This difference is greater for off-nadir views and also appears to be larger in the spring and summer than in the fall and winter.
机译：我们使用能量多光谱热成像仪（MTI）所获取的数据来测量冬季针叶林的定向反射率和日间温度。研究网站是缅因州中部的霍兰·实验森林。这些数据包括从2001 - 2002年的一年时间内的所有季节的测量，但在冬季和早春的浓度下。结果表明，方向和季节的反射率和温度的变化。反射率结果有利地比较了在榴域网站上进行的先前双向测量。可见乐队中的近Nadir反射率在今年中周期性周期性，夏季高，冬季较低。近红外（NIR）反射率显示双变量。顶篷反射率随太阳能和卫星天顶角的函数而变化，可能是由于阴影比例变化。此外，NIR伪BRDF（双向反射率分布函数）表明秋季和冬季的冠层在尼尔中发亮。检索到的冠层温度在偏离Nadir视图中持续加热约2°C，季节性变化小。季节性冠层温度趋势良好呈现很好，地面上有雪的日子很容易区别于地面上没有雪的日子。结果还表明，检出的温度始终比高于篷布空气温度持续约4℃。对于非Nadir观点来说，这种差异更大，并且在春季和夏天也比秋季和冬天更大。

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