{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/33203"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/33203","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"A Phenological Comparison of NDVI Products within Contiguous United States","abstract":"This study computed the Normalized Difference Vegetation Index (NDVI) products derived from NOAA AVHRR, MODIS, and SPOT VGT sensors. NDVI products from different instruments vary in spatial resolution, temporal coverage and spectral range. As a result, multi-sensor NDVI products are rarely used in a single phenological study. In order to evaluate the difference and similarity of NDVI records from the three sensors, I used EPA Eco-region frameworks to determine the average annual Start of Season (SOS) and End of Season (EOS) of Contiguous United States, and analyzed dates among datasets. In addition, I created 1127 sample points within the study area, and compared relationship between SOS/EOS based on land cover. The objectives of this thesis are to: 1) compare multi-sensor NDVI data using phenological models, 2) define a strategy to merge multi-sensor NDVI products to a single phenological product without direct NDVI conversion. The spatial and statistical analysis revealed that the Land Surface Phenology (LSP) measurements retrieved from NDVI time series from different sensors follow linear and positive relationships where compared by either eco-region or sample point. The historical record of AVHRR combined with the modern MODIS and SPOT data provides a critical and reliable perspective on phenological patterns in Contiguous United States area. The success of this study will help LSP by providing understanding of how different instruments can be combined to generate multi-sensor NDVI data for phenology.","abstract_html":"This study computed the Normalized Difference Vegetation Index (NDVI) products derived from NOAA AVHRR, MODIS, and SPOT VGT sensors. NDVI products from different instruments vary in spatial resolution, temporal coverage and spectral range. As a result, multi-sensor NDVI products are rarely used in a single phenological study. In order to evaluate the difference and similarity of NDVI records from the three sensors, I used EPA Eco-region frameworks to determine the average annual Start of Season (SOS) and End of Season (EOS) of Contiguous United States, and analyzed dates among datasets. In addition, I created 1127 sample points within the study area, and compared relationship between SOS/EOS based on land cover. The objectives of this thesis are to: 1) compare multi-sensor NDVI data using phenological models, 2) define a strategy to merge multi-sensor NDVI products to a single phenological product without direct NDVI conversion. The spatial and statistical analysis revealed that the Land Surface Phenology (LSP) measurements retrieved from NDVI time series from different sensors follow linear and positive relationships where compared by either eco-region or sample point. The historical record of AVHRR combined with the modern MODIS and SPOT data provides a critical and reliable perspective on phenological patterns in Contiguous United States area. The success of this study will help LSP by providing understanding of how different instruments can be combined to generate multi-sensor NDVI data for phenology.","abstract_has_math":false,"creators":["Chai, Jiaxun"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Geography","degree_department":"Geography","school":null,"contributors":[],"advisors":[],"committee_chairs":["de Beurs, Kirsten M."],"committee_members":["Carstensen, Laurence W.","Campbell, James B. Jr."],"year":2011,"date_issued":"2011-05-16","date_published":"2011-05-16","updated_at":"2026-07-22T22:18:55Z","subjects":["SPOT","MODIS","AVHRR","Eco-region","NDVI","Phenology"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-05242011-114850"],"render_values":[{"text":"etd-05242011-114850","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/33203","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["de Beurs, Kirsten M."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Carstensen, Laurence W.","Campbell, James B. Jr."]},{"key":"dc:contributor.department","label":"Department","values":["Geography"]},{"key":"dc:creator","label":"Author","values":["Chai, Jiaxun"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T20:38:30Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T20:38:30Z","2011-07-14"]},{"key":"dc:date.issued","label":"Date","values":["2011-05-16"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Geography"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["SPOT","MODIS","AVHRR","Eco-region","NDVI","Phenology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-05242011-114850"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/33203"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This study computed the Normalized Difference Vegetation Index (NDVI) products derived from NOAA AVHRR, MODIS, and SPOT VGT sensors. NDVI products from different instruments vary in spatial resolution, temporal coverage and spectral range. As a result, multi-sensor NDVI products are rarely used in a single phenological study. In order to evaluate the difference and similarity of NDVI records from the three sensors, I used EPA Eco-region frameworks to determine the average annual Start of Season (SOS) and End of Season (EOS) of Contiguous United States, and analyzed dates among datasets. In addition, I created 1127 sample points within the study area, and compared relationship between SOS/EOS based on land cover. The objectives of this thesis are to: 1) compare multi-sensor NDVI data using phenological models, 2) define a strategy to merge multi-sensor NDVI products to a single phenological product without direct NDVI conversion. The spatial and statistical analysis revealed that the Land Surface Phenology (LSP) measurements retrieved from NDVI time series from different sensors follow linear and positive relationships where compared by either eco-region or sample point. The historical record of AVHRR combined with the modern MODIS and SPOT data provides a critical and reliable perspective on phenological patterns in Contiguous United States area. The success of this study will help LSP by providing understanding of how different instruments can be combined to generate multi-sensor NDVI data for phenology."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:title","label":"Title","values":["A Phenological Comparison of NDVI Products within Contiguous United States"]}]}],"canonical_facts":{"dc:contributor.committeechair":["de Beurs, Kirsten M."],"dc:contributor.committeemember":["Carstensen, Laurence W.","Campbell, James B. Jr."],"dc:contributor.department":["Geography"],"dc:creator":["Chai, Jiaxun"],"dc:date.accessioned":["2014-03-14T20:38:30Z"],"dc:date.available":["2014-03-14T20:38:30Z","2011-07-14"],"dc:date.issued":["2011-05-16"],"dc:description.abstract":["This study computed the Normalized Difference Vegetation Index (NDVI) products derived from NOAA AVHRR, MODIS, and SPOT VGT sensors. NDVI products from different instruments vary in spatial resolution, temporal coverage and spectral range. As a result, multi-sensor NDVI products are rarely used in a single phenological study. In order to evaluate the difference and similarity of NDVI records from the three sensors, I used EPA Eco-region frameworks to determine the average annual Start of Season (SOS) and End of Season (EOS) of Contiguous United States, and analyzed dates among datasets. In addition, I created 1127 sample points within the study area, and compared relationship between SOS/EOS based on land cover. The objectives of this thesis are to: 1) compare multi-sensor NDVI data using phenological models, 2) define a strategy to merge multi-sensor NDVI products to a single phenological product without direct NDVI conversion. The spatial and statistical analysis revealed that the Land Surface Phenology (LSP) measurements retrieved from NDVI time series from different sensors follow linear and positive relationships where compared by either eco-region or sample point. The historical record of AVHRR combined with the modern MODIS and SPOT data provides a critical and reliable perspective on phenological patterns in Contiguous United States area. The success of this study will help LSP by providing understanding of how different instruments can be combined to generate multi-sensor NDVI data for phenology."],"dc:description.degree":["Master of Science"],"dc:identifier.other":["etd-05242011-114850"],"dc:identifier.uri":["http://hdl.handle.net/10919/33203"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["SPOT","MODIS","AVHRR","Eco-region","NDVI","Phenology"],"dc:title":["A Phenological Comparison of NDVI Products within Contiguous United States"],"dc:type":["Thesis"],"thesis:degree_discipline":["Geography"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:18:55Z"}