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Articles 1 - 8 of 8
Full-Text Articles in Physical and Environmental Geography
Responses Of Land Surface Phenology To Wildfire Disturbances In The Western United States Forests, Jianmin Wang
Responses Of Land Surface Phenology To Wildfire Disturbances In The Western United States Forests, Jianmin Wang
Electronic Theses and Dissertations
Land surface phenology (LSP) characterizes the seasonal dynamics in the vegetation communities observed for a satellite pixel and it has been widely associated with global climate change. However, LSP and its long-term trend can be influenced by land disturbance events, which could greatly interrupt the LSP responses to climate change. Wildfire is one of the main disturbance agents in the western United States (US) forests, but its impacts on LSP have not been investigated yet. To gain a comprehensive understanding of the LSP responses to wildfires in the western US forests, this dissertation focused on three research objectives: (1) to …
How Are Interannual Variations Of Land Surface Phenology In The Highland Pastures Of Kyrgyzstan Modulated By Terrain, Snow Cover Seasonality, And Climate Oscillations? An Investigation Using Multi-Source Remote Sensing Data, Monika Anna Tomaszewska
How Are Interannual Variations Of Land Surface Phenology In The Highland Pastures Of Kyrgyzstan Modulated By Terrain, Snow Cover Seasonality, And Climate Oscillations? An Investigation Using Multi-Source Remote Sensing Data, Monika Anna Tomaszewska
Electronic Theses and Dissertations
In the semiarid, continental climates of montane Central Asia, with its constant moisture deficit and low relative humidity, agropastoralism constitutes the foundation of the rural economy. In Kyrgyzstan, an impoverished, landlocked republic in Central Asia, herders of the highlands practice vertical transhumance—the annual movement of livestock to higher elevation pastures to take advantage of seasonally available forage resources. Dependency on pasture resource availability during the short mountain growing season makes herds and herders susceptible to changing weather and climate patterns. This dissertation focuses on using remote sensing observations over the highland pastures in Kyrgyzstan to address five interrelated topics: (i) …
Satellite Remote Sensing Of Woody And Herbaceous Leaf Area For Improved Understanding Of Forage Resources And Fire In Africa, Milkah Njoki Kahiu
Satellite Remote Sensing Of Woody And Herbaceous Leaf Area For Improved Understanding Of Forage Resources And Fire In Africa, Milkah Njoki Kahiu
Electronic Theses and Dissertations
In sub-Saharan Africa (SSA) tree-grass systems commonly referred to as savannas dominating drylands, play a critical role in social, cultural, economic and environmental systems. These coupled natural-human systems support millions of people through pastoralism, are important global biodiversity hotspots and play a critical role in global biogeochemical cycles. Despite the importance of SSA savannas, they have been marginalized for years as most governments neglect dryland resources in favor of agricultural research and development assistance. Hence, lack of spatially and temporally accurate information on the status and trends in savanna resources has led to poor planning and management. This scenario calls …
Examination Of Sentinel-2a Multi-Spectral Instrument (Msi) Reflectance Anisotropy And The Suitability Of A General Method To Normalize Msi Reflectance To Nadir Brdf Adjusted Reflectance, David P. Roy, Jian Li, Hankui Zhang, Lin Yan Dr., Haiyan Huang, Zhongbin Li
Examination Of Sentinel-2a Multi-Spectral Instrument (Msi) Reflectance Anisotropy And The Suitability Of A General Method To Normalize Msi Reflectance To Nadir Brdf Adjusted Reflectance, David P. Roy, Jian Li, Hankui Zhang, Lin Yan Dr., Haiyan Huang, Zhongbin Li
GSCE Faculty Publications
The Sentinel-2A multi-spectral instrument (MSI) acquires multi-spectral reflective wavelength observations with directional effects due to surface reflectance anisotropy and changes in the solar and viewing geometry. Directional effects were examined by considering two ten day periods of Sentinel-2A data acquired close to the solar principal and orthogonal planes over approximately 20° × 10° of southern Africa. More than 6.6 million (January 2016) and 10.6 million (April 2016) pairs of reflectance observations sensed 3 or 7 days apart in the forward and backscatter directions in overlapping Sentinel-2A orbit swaths were considered. The Sentinel-2A data were projected into the MODIS sinusoidal projection …
Using The 500 M Modis Land Cover Product To Derive A Consistent Continental Scale 30 M Landsat Land Cover Classification, Hankui Zhang, David P. Roy
Using The 500 M Modis Land Cover Product To Derive A Consistent Continental Scale 30 M Landsat Land Cover Classification, Hankui Zhang, David P. Roy
GSCE Faculty Publications
Classification is a fundamental process in remote sensing used to relate pixel values to land cover classes present on the surface. Over large areas land cover classification is challenging particularly due to the cost and difficulty of collecting representative training data that enable classifiers to be consistent and locally reliable. A novel methodology to classify large volume Landsat data using high quality training data derived from the 500 m MODIS land cover product is demonstrated and used to generate a 30 m land cover classification for all of North America between 20°N and 50°N. Publically available 30 m global monthly …
A General Method To Normalize Landsat Reflectance Data To Nadir Brdf Adjusted Reflectance, David P. Roy, Hankui Zhang, Junchang Ju, Jose Luis Gomez-Dans, Philip E. Lewis, Crystal Barker B. Schaaf, Qingsong Sun, Jian Li, Haiyan Huang, V. Kovalskyy
A General Method To Normalize Landsat Reflectance Data To Nadir Brdf Adjusted Reflectance, David P. Roy, Hankui Zhang, Junchang Ju, Jose Luis Gomez-Dans, Philip E. Lewis, Crystal Barker B. Schaaf, Qingsong Sun, Jian Li, Haiyan Huang, V. Kovalskyy
GSCE Faculty Publications
The Landsat satellites have been providing spectacular imagery of the Earth's surface for over 40 years. However, they acquire images at view angles ±7.5° from nadir that cause small directional effects in the surface reflectance. There are also variations with solar zenith angle over the year that can cause apparent change in reflectance even if the surface properties remain constant. When Landsat data from adjoining paths, or from long time series are used, a model of the surface anisotropy is required to adjust all Landsat observations to a uniform nadir view (primarily for visual consistency, vegetation monitoring, or detection of …
Change And Persistence In Land Surface Phenologies Of The Don And Dnieper River Basins, V. Kovalskyy, G. M. Henebry
Change And Persistence In Land Surface Phenologies Of The Don And Dnieper River Basins, V. Kovalskyy, G. M. Henebry
Natural Resource Management Faculty Publications
The formal collapse of the Soviet Union at the end of 1991 produced major socio-economic and institutional dislocations across the agricultural sector. The picture of broad scale patterns produced by these transformations continues to be discovered. We examine here the patterns of land surface phenology (LSP) within two key river basins—Don and Dnieper—using AVHRR (Advanced Very High Resolution Radiometer) data from 1982 to 2000 and MODIS (Moderate Resolution Imaging Spectroradiometer) data from 2001 to 2007. We report on the temporal persistence and change of LSPs as summarized by seasonal integration of NDVI (normalized difference vegetation index) time series using accumulated …
Dual Scale Trend Analysis Distinguishes Climatic From Anthropogenic Effects On The Vegetated Land Surface, K. M. De Beurs, C. K. Wright, G. M. Henebry
Dual Scale Trend Analysis Distinguishes Climatic From Anthropogenic Effects On The Vegetated Land Surface, K. M. De Beurs, C. K. Wright, G. M. Henebry
Natural Resource Management Faculty Publications
We present a dual scale trend analysis for characterizing and comparing two contrasting areas of change in Russia and Kazakhstan that lie less than 800 km apart. We selected a global NASA MODIS (moderate resolution imaging spectroradiometer) product (MCD43C4 and MCD43A4) at a 0.05◦ (∼5.6 km) and 500 m spatial resolution and a 16-day temporal resolution from 2000 to 2008. We applied a refinement of the seasonal Kendall trend method to the normalized difference vegetation index (NDVI) image series at both scales. We only incorporated composites during the vegetative growing season which was delineated by start of season and end …