Amazon forest spectral seasonality is consistent across sensor resolutions and driven by leaf demography
Amazon forest spectral seasonality is consistent across sensor resolutions and driven by leaf demography
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亚马逊森林光谱季节性在传感器分辨率上保持一致，并由树叶人口统计驱动
DOI：
10.1016/j.isprsjprs.2022.12.001
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发表时间：
2023
影响因子：
12.7
通讯作者：
Nelson, Bruce W.
中科院分区：
文献类型：
--
作者：
Gonçalves, Nathan B.;Dalagnol, Ricardo;Wu, Jin;Pontes-Lopes, Aline;Stark, Scott C.;Nelson, Bruce W.
围绕亚马逊中部森林旱季绿化的报道存在争议，该报告基于中分辨率成像光谱仪(MODIS)的增强植被指数(EVI)。在旱季，随着太阳天顶角的减小，它会影响亚像素的遮荫含量，并人为地增加近红外(NIR)反射率和EVI。MODIS的粗略分辨率也给云和地形过滤带来了挑战。为了减少这些伪影，然后验证MODIS季节性光谱模式，我们使用了16年来1公里分辨率的MODIS-MAIAC(大气校正的多角度实施)图像，校正到最低角和45°太阳天顶角，以及改进的云过滤器。然后，我们发现，30米长的陆地成像仪(OLI)在两个陆地卫星场景上的地表反射率提供了独立的证据，支持EVI、近红外和GCC(另一个重要的植被指数，绿色色度坐标)的MODIS-MAIAC季节性。我们在陆地卫星场景中控制太阳传感器几何效果的经验方法包括使用季节性不同的图像，这些图像具有相似的太阳天顶角和具有相同相位角的平坦高地上的无云像素。我们将这一验证扩展到包括∼546 Landsat-8图像的9个亚马逊子盆地。我们的研究表明，MODIS观测到的旱季绿光模式得到了Landsat-8的证实，并且与卫星数据的伪像无关。为了研究这些季节变化的驱动机制，我们进一步使用了亚马逊中部塔式RGB相机，该相机在亚马逊高塔(ATTO，2°8‘36“S，59°0’2”西经)创造了4年纪录，在马瑙斯k34塔楼(2°36‘33“S，60°12’33”西经)创造了7年纪录，以获得每月冠层上部绿叶覆盖率(叶面积指数-LAI的替代指标)和每月叶龄类丰度(基于树冠自叶冲后的年龄)。将这些数据与以每个塔为中心的MODIS-MAIAC小窗口中的GCC和EVI的季节模式进行了比较。MODIS-MAIAC GCC与新抽叶呈显著正相关(R2=0.76和0.44)。EVI与成熟叶丰度显著相关(R2=0.82和0.80)，与叶面积指数相关性较差(R2=0.20和0.41)。因此，亚马逊中部的季节光谱模式可能受叶龄变化的控制，而不是叶面积的数量。
Controversy surrounds the reported dry season greening of the Central Amazon forests based on the Enhanced Vegetation Index (EVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS). As the solar zenith angle decreases during the dry season, it affects the sub-pixel shade content and artificially increases Near-infrared (NIR) reflectance and EVI. MODIS' coarse resolution also creates a challenge for cloud and terrain filtering. To reduce these artifacts and then validate MODIS seasonal spectral patterns we use 16 years of 1 km resolution MODIS-MAIAC (Multi-Angle Implementation of Atmospheric Correction) images, corrected to a nadir view and 45° solar zenith angle, together with an improved cloud filter. Then we show that the 30 m Landsat-8 Operational Land Imager (OLI) surface reflectance over two Landsat scenes provides independent evidence supporting the MODIS-MAIAC seasonality for EVI, NIR, and GCC (an additional important vegetation index, green chromatic coordinate). Our empirical method for controlling for sun-sensor geometry effects in Landsat scenes encompasses the use of seasonally distinct images that have similar solar zenith angles and cloud-free pixels on flat uplands having the same phase angle. We extended this validation to nine Amazon sub-basins comprising ∼546 Landsat-8 images. Our study shows that the dry-season green-up pattern observed by MODIS is corroborated by Landsat-8, and is independent of satellite data artifacts. To investigate the mechanisms driving these seasonal changes we further used Central Amazon tower-mounted RGB cameras providing a 4-year record at the Amazon Tall Tower (ATTO, 2°8′36″S, 59°0′2″W) and a 7-year record at the Manaus k34 tower (2°36′33″ S, 60°12′33″W) to obtain monthly upper canopy green leaf cover (a proxy for Leaf Area Index - LAI) and monthly leaf age class abundances (based on the age since leaf flushing, by crown). These were compared to seasonal patterns of GCC and EVI in small MODIS-MAIAC windows centered on each tower. MODIS-MAIAC GCC was positively correlated with newly flushed leaves (R2= 0.76 and 0.44 at ATTO and k34, respectively). EVI correlated strongly with the abundance of mature leaves (R2= 0.82 and 0.80) but was poorly correlated with LAI (R2= 0.20 and 0.41, respectively). Therefore, seasonal spectral patterns in the Central Amazon are likely controlled by leaf age variation, not quantity of leaf area.
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DOI：
10.1016/j.isprsjprs.2021.10.023
发表时间：
2022-01
影响因子：
12.7
作者：
Guangqin Song;Shengbiao Wu;Calvin K. F. Lee;S. Serbin;B. Wolfe;Michael K. Ng;Kim S. Ely;Marc Bogonovich;Jing Wang;Ziyu Lin;S. Saleska;B. Nelson;A. Rogers;Jin Wu
通讯作者：
Guangqin Song;Shengbiao Wu;Calvin K. F. Lee;S. Serbin;B. Wolfe;Michael K. Ng;Kim S. Ely;Marc Bogonovich;Jing Wang;Ziyu Lin;S. Saleska;B. Nelson;A. Rogers;Jin Wu
DOI：
--
发表时间：
2016
期刊：
影响因子：
--
作者：
Lucas Kosvoski de Ourique;Rosiane de Oliveira Silva;Cacilda de Souza;Hideyuki Noguchi;Joaquim Rocha dos Santos;N. Higuchi
通讯作者：
N. Higuchi
太阳传感器几何形状对亚马逊雨林植被指数异常的影响
影响因子：
6.7
作者：
E. Maeda;L. Galvão
通讯作者：
L. Galvão
影响因子：
2
作者：
Hess, Laura L.;Melack, John M.;Novo, Evlyn M. L. M.
通讯作者：
Novo, Evlyn M. L. M.
亚马逊水生生态系统保护的基于 GIS 的明确流域框架
DOI：
--
发表时间：
2016
期刊：
影响因子：
--
作者：
E. Venticinque;B. Forsberg;R. Barthem;P. Petry;L. Hess;A. Mercado;C. Cañas;Mariana Montoya;C. Durigan;M. Goulding
通讯作者：
M. Goulding