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Full-Text Articles in Physical Sciences and Mathematics

Landsat 5 Thematic Mapper Reflectance And Ndvi 27-Year Time Series Inconsistencies Due To Satellite Orbit Change, Hankui Zhang, David P. Roy Dec 2016

Landsat 5 Thematic Mapper Reflectance And Ndvi 27-Year Time Series Inconsistencies Due To Satellite Orbit Change, Hankui Zhang, David P. Roy

GSCE Faculty Publications

The Landsat 5 Thematic Mapper (TM) sensor provided the longest single mission terrestrial remote sensing data record but temporally sparse station keeping maneuvers meant that the Landsat 5 orbit changed over the 27 year mission life. Long-term Landsat 5 TM reflectance inconsistencies may be introduced by orbit change induced solar zenith variations combined with surface reflectance anisotropy, commonly described by the Bi-directional Reflectance Distribution Function (BRDF). This study quantifies the local overpass time and observed solar zenith angle changes for all the Landsat 5 TM images available at two latitudinally separated locations along the same north-south Landsat path (27) in …


Separability Analysis Of Sentinel-2a Multi-Spectral Instrument (Msi) Data For Burned Area Discrimination, Haiyan Huang, David P. Roy, Luigi Boschetti, Hankui Zhang, Lin Yan Dr., Sanath Sathyachandran Kumar, Jose Gomez-Dans, Jian Li Oct 2016

Separability Analysis Of Sentinel-2a Multi-Spectral Instrument (Msi) Data For Burned Area Discrimination, Haiyan Huang, David P. Roy, Luigi Boschetti, Hankui Zhang, Lin Yan Dr., Sanath Sathyachandran Kumar, Jose Gomez-Dans, Jian Li

GSCE Faculty Publications

: Biomass burning is a global phenomenon and systematic burned area mapping is of increasing importance for science and applications. With high spatial resolution and novelty in band design, the recently launched Sentinel-2A satellite provides a new opportunity for moderate spatial resolution burned area mapping. This study examines the performance of the Sentinel-2A Multi Spectral Instrument (MSI) bands and derived spectral indices to differentiate between unburned and burned areas. For this purpose, five pairs of pre-fire and post-fire top of atmosphere (TOA reflectance) and atmospherically corrected (surface reflectance) images were studied. The pixel values of locations that were unburned in …


A Comparison Of Tropical Rainforest Phenology Retrieved From Geostationary (Seviri) And Polar-Orbiting (Modis) Sensors Across The Congo Basin, Dong Yan, Xiaoyang Zhang, Yunyue Yu, Wei Guo Aug 2016

A Comparison Of Tropical Rainforest Phenology Retrieved From Geostationary (Seviri) And Polar-Orbiting (Modis) Sensors Across The Congo Basin, Dong Yan, Xiaoyang Zhang, Yunyue Yu, Wei Guo

GSCE Faculty Publications

The seasonal and interannual dynamics of tropical rainforests play a critical role in the global carbon cycle and climate change. This paper retrieved and compared land surface phenology from observations acquired by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard geostationary satellites and the Moderate Resolution Imaging Spectroradiometer (MODIS) on polar-orbiting satellites over the Congo Basin. To achieve this,we first retrieved canopy greenness cycles (CGCs) and their transition timing from two-band enhanced vegetation index (EVI2) derived from SEVIRI and MODIS data between 2006 and 2013.We then assessed the influences of SEVIRI and MODIS data quality on the reconstruction of …


The Influences Of Drought And Land-Cover Conversion On Inter-Annual Variation Of Npp In The Three-North Shelterbelt Program Zone Of China Based On Modis Data, Dailiang Peng, Chaoyang Wu, Bing Zhang, Alfredo Huete, Xiaoyang Zhang, Rui Sun, Liping Lei, Wenjing Huang, Liangyun Liu, Xinjie Liu, Jun Li, Shezhou Luo, Bin Fang Jun 2016

The Influences Of Drought And Land-Cover Conversion On Inter-Annual Variation Of Npp In The Three-North Shelterbelt Program Zone Of China Based On Modis Data, Dailiang Peng, Chaoyang Wu, Bing Zhang, Alfredo Huete, Xiaoyang Zhang, Rui Sun, Liping Lei, Wenjing Huang, Liangyun Liu, Xinjie Liu, Jun Li, Shezhou Luo, Bin Fang

GSCE Faculty Publications

Terrestrial ecosystems greatly contribute to carbon (C) emission reduction targets through photosynthetic C uptake.Net primary production (NPP) represents the amount of atmospheric C fixed by plants and accumulated as biomass. The Three-North Shelterbelt Program (TNSP) zone accounts for more than 40% of China’s landmass. This zone has been the scene of several large-scale ecological restoration efforts since the late 1990s, and has witnessed significant changes in climate and human activities.Assessing the relative roles of different causal factors on NPP variability in TNSP zone is very important for establishing reasonable local policies to realize the emission reduction targets for central government. …


Mapping Temperate Vegetation Climate Adaptation Variability Using Normalized Land Surface Phenology, Liang Liang, Mark D. Schwartz, Xiaoyang Zhang Apr 2016

Mapping Temperate Vegetation Climate Adaptation Variability Using Normalized Land Surface Phenology, Liang Liang, Mark D. Schwartz, Xiaoyang Zhang

GSCE Faculty Publications

Climate influences geographic differences of vegetation phenology through both contemporary and historical variability. The latter effect is embodied in vegetation heterogeneity underlain by spatially varied genotype and species compositions tied to climatic adaptation. Such long-term climatic effects are difficult to map and therefore often neglected in evaluating spatially explicit phenological responses to climate change. In this study we demonstrate a way to indirectly infer the portion of land surface phenology variation that is potentially contributed by underlying genotypic differences across space. The method undertaken normalized remotely sensed vegetation start-of-season (or greenup onset) with a cloned plants-based phenological model. As the …