Use of NDVI and Land Surface Temperature for Drought Assessment: Merits and Limitations
Use of NDVI and Land Surface Temperature for Drought Assessment: Merits and Limitations
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DOI：
10.1175/2009jcli2900.1
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发表时间：
2010-02-01
影响因子：
4.9
通讯作者：
Goldberg, Alexander
中科院分区：
文献类型：
--
作者：
Karnieli, Arnon;Agam, Nurit;Goldberg, Alexander
许多与水和气候有关的应用，如干旱监测，都是基于从空间数据中得出的地表温度与归一化植被指数之间的关系。这些应用中的大多数依赖于两个变量之间存在的负斜率，如在特定地点和特定时间的研究中所确定的。目前的文件调查的LST-NDVI关系的一般性，在北美大陆（高达60度N）在夏季生长季节（4月至9月）遇到的广泛的水分和气候/辐射制度。关于LST和NDVI的信息是从高级甚高分辨率辐射计（AVHRR）获取的长期（21年）数据集获得的。结果发现，当水是植被生长的限制因子（典型的情况下，低纬度的研究区域和在旺季），LST的NDVI相关性是负的。然而，当能量是植被生长的限制因素时（在高纬度和高海拔地区，特别是在生长季节开始时），LST和NDVI之间存在正相关关系。多元回归分析表明，在生长季节的开始和结束，太阳辐射是主导因素驱动LST和NDVI之间的相关性，而其他生物物理变量发挥较小的作用。在盛夏，气温是主要因素。它的结论是，有必要谨慎使用经验LST-NDVI关系，并限制其应用于干旱监测的地区和时期，观察到负相关性，即条件时，水，而不是能源，是限制植被生长的主要因素。
A large number of water- and climate-related applications, such as drought monitoring, are based on spaceborne-derived relationships between land surface temperature (LST) and the normalized difference vegetation index (NDVI). The majority of these applications rely on the existence of a negative slope between the two variables, as identified in site- and time-specific studies. The current paper investigates the generality of the LST-NDVI relationship over a wide range of moisture and climatic/radiation regimes encountered over the North American continent (up to 60 degrees N) during the summer growing season (April-September). Information on LST and NDVI was obtained from long-term (21 years) datasets acquired with the Advanced Very High Resolution Radiometer (AVHRR). It was found that when water is the limiting factor for vegetation growth (the typical situation for low latitudes of the study area and during the midseason), the LST NDVI correlation is negative. However, when energy is the limiting factor for vegetation growth (in higher latitudes and elevations, especially at the beginning of the growing season), a positive correlation exists between LST and NDVI. Multiple regression analysis revealed that during the beginning and the end of the growing season, solar radiation is the predominant factor driving the correlation between LST and NDVI, whereas other biophysical variables play a lesser role. Air temperature is the primary factor in midsummer. It is concluded that there is a need to use empirical LST-NDVI relationships with caution and to restrict their application to drought monitoring to areas and periods where negative correlations are observed, namely, to conditions when water-not energy-is the primary factor limiting vegetation growth.