Reanalysis of global terrestrial vegetation trends from MODIS products: Browning or greening?
Reanalysis of global terrestrial vegetation trends from MODIS products: Browning or greening?
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DOI：
10.1016/j.rse.2016.12.018
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发表时间：
2017-03
影响因子：
13.5
通讯作者：
Yulong Zhang;C. Song;L. Band;G. Sun;Junxiang Li
中科院分区：
文献类型：
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作者：
Yulong Zhang;C. Song;L. Band;G. Sun;Junxiang Li
利用现代遥感技术准确监测全球植被动态对于了解生物圈的功能和过程及其与行星气候的相互作用至关重要。中分辨率成像分光辐射计的植被指数产品是这方面的主要数据来源。到目前为止，中分辨率成像分光仪小组已经发布了几个版本的可视信息产品，这些产品已广泛用于全球变化研究和实际应用。在这项研究中，我们重新研究了全球植被活动，通过比较最近的MODIS Collection 6（C6）维斯与Collection 5（C5）维斯，包括归一化差异植被指数（NDVI）和增强植被指数（EVI）从Terra（2001-2015）和Aqua Saintland（2003-2015）。我们发现，在全球植被的趋势terra-C5和-C6维斯，特别是EVI之间的重大差异。从2001年到2015年，全球植被在Terra-C6的年度EVI中显示出显着的绿化趋势（0.28%年-1; P < 0.001），与Terra-C5的EVI下降趋势（-0.14%年-1，P < 0.01）形成对比。在空间上，由Terra-C5维斯识别的热带地区的大部分布朗宁区域在Terra-C6维斯中不明显。相比之下，Terra-C6维斯中广泛的绿化面积与Aqua-C6维斯和GIMMS 3g NDVI一致。我们发现的绿化地球支持最近的研究表明，加强土地碳汇。我们的研究表明，大多数的植被布朗宁的趋势检测中分辨率成像光谱仪Terra-C5维斯可能是由传感器退化，特别是在2007年后的一段时间。因此，可能需要重新评估以前仅基于Terra-C5维斯的时间植被趋势研究。我们的新分析提供了对过去15年全球植被动态的最新了解，有助于准确理解植被在地球地球化学和气候系统中的作用。
Accurately monitoring global vegetation dynamics with modern remote sensing is critical for understanding the functions and processes of the biosphere and its interactions with the planetary climate. The MODerate resolution Imaging Spectroradiometer (MODIS) vegetation index (VI) product has been a primary data source for this purpose. To date, the MODIS team had released several versions of VI products that have widely used in global change studies and practical applications. In this study, we re-examined the global vegetation activity by comparing the recent MODIS Collection 6 (C6) VIs with Collection 5 (C5) VIs including Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) from Terra (2001–2015) and Aqua Satellites (2003–2015). We found substantial differences in global vegetation trends betweenTerra-C5 and -C6 VIs, especially EVI. From 2001 to 2015, global vegetation showed a remarkable greening trend in annual EVI from the Terra-C6 (0.28% year− 1; P < 0.001), in contrast to the decreasing EVI trend from the Terra-C5 (− 0.14% year− 1, P < 0.01). Spatially, large portions of the browning areas in tropical regions identified by Terra-C5 VIs were not evident in Terra-C6 VIs. In contrast, the widespread greening areas in Terra-C6 VIs were consistent with Aqua-C6 VIs and GIMMS3g NDVI. Our finding of a greening Earth supports the recent studies suggesting an enhanced land carbon sink. Our study suggests that most of the vegetation browning trends detected by MODIS Terra-C5 VIs were likely caused by sensor degradation, particularly for the period after 2007. Therefore, previous studies of temporal vegetation trends based solely on Terra-C5 VIs may need to be reevaluated. Our new analysis offers the most updated understanding of the global vegetation dynamics during the past 15 years and contributes to accurately understanding the role of vegetation played in the Earth's biogeochemical and climatic systems.