{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/140839"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/140839","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"From Hyperspectral Indices to Global Fluorescence: PACE Vegetation Indices as Predictors of Terrestrial Photosynthesis","abstract":"Solar-induced chlorophyll fluorescence (SIF) serves as a direct remotely sensed indicator of photosynthetic activity, making it a valuable tool for assessing terrestrial productivity. However, the practical application of satellite-derived SIF is hindered by spatial resolution limitations and data gaps. The NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission presents an opportunity to overcome these challenges through its hyperspectral Ocean Color Instrument and globally distributed Land Vegetation Index (LANDVI) product suite. This study's primary contribution lies in demonstrating that PACE vegetation indices alone can reliably predict SIF from global retrievals obtained using data from the Copernicus Sentinel-5P Tropospheric Monitoring Instrument (TROPOMI), even in the absence of PACE BRDF and albedo products (and their associated corrections). Using 8-day global composites from 2024, we establish a temporal and spatial correlation between PACE indices and TROPOMI SIF (TROPOSIF) across fifteen biome-stratified study regions, including forests, grasslands, agricultural systems, and xeric landscapes. Simple univariate linear models reveal that the Enhanced Vegetation Index (EVI) and the Chlorophyll Index Red Edge (CIRE) are the most reliable global predictors of SIF, accounting for 80% and 77% of the variance, respectively. Notably, the stability of the EVI-SIF and CIRE-SIF relationships across seasons further emphasizes the significant role of canopy structure and chlorophyll information captured by these two indices in explaining global SIF variability. Seasonal analyses indicate that while EVI and CIRE are most effective in most forests and agricultural systems, moisture-sensitive indices and pigment indices perform better during dry seasons and transitional periods in water-limited ecosystems. Spatial residual analyses suggest minimal global bias but systematic underestimation in boreal forests and selected tropical regions, which aligns with established effects of canopy architecture and fluorescence escape probability. Considering that EVI, in particular, is available even from moderate-resolution Earth resource satellite missions such as Sentinel-2 and Landsat, there is substantial potential for SIF downscaling to management and policy-relevant scales.","abstract_html":"Solar-induced chlorophyll fluorescence (SIF) serves as a direct remotely sensed indicator of photosynthetic activity, making it a valuable tool for assessing terrestrial productivity. However, the practical application of satellite-derived SIF is hindered by spatial resolution limitations and data gaps. The NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission presents an opportunity to overcome these challenges through its hyperspectral Ocean Color Instrument and globally distributed Land Vegetation Index (LANDVI) product suite. This study's primary contribution lies in demonstrating that PACE vegetation indices alone can reliably predict SIF from global retrievals obtained using data from the Copernicus Sentinel-5P Tropospheric Monitoring Instrument (TROPOMI), even in the absence of PACE BRDF and albedo products (and their associated corrections). Using 8-day global composites from 2024, we establish a temporal and spatial correlation between PACE indices and TROPOMI SIF (TROPOSIF) across fifteen biome-stratified study regions, including forests, grasslands, agricultural systems, and xeric landscapes. Simple univariate linear models reveal that the Enhanced Vegetation Index (EVI) and the Chlorophyll Index Red Edge (CIRE) are the most reliable global predictors of SIF, accounting for 80% and 77% of the variance, respectively. Notably, the stability of the EVI-SIF and CIRE-SIF relationships across seasons further emphasizes the significant role of canopy structure and chlorophyll information captured by these two indices in explaining global SIF variability. Seasonal analyses indicate that while EVI and CIRE are most effective in most forests and agricultural systems, moisture-sensitive indices and pigment indices perform better during dry seasons and transitional periods in water-limited ecosystems. Spatial residual analyses suggest minimal global bias but systematic underestimation in boreal forests and selected tropical regions, which aligns with established effects of canopy architecture and fluorescence escape probability. Considering that EVI, in particular, is available even from moderate-resolution Earth resource satellite missions such as Sentinel-2 and Landsat, there is substantial potential for SIF downscaling to management and policy-relevant scales.","abstract_has_math":false,"creators":["Harmon, Caleb Sloan"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Forestry","degree_department":"Forest Resources and Environmental Conservation","school":null,"contributors":[],"advisors":[],"committee_chairs":["Wynne, Randolph H.","Thomas, Valerie Anne"],"committee_members":["Huemmrich, Karl Fred"],"year":2026,"date_issued":"2026-01-15","date_published":"2026-01-15","updated_at":"2026-07-22T22:19:16Z","subjects":["Solar-induced chlorophyll fluorescence","PACE mission","Ocean Color Instrument","Hyperspectral vegetation indices","Enhanced Vegetation Index","Chlorophyll Index Red Edge","Gross Primary Productivity","Global terrestrial ecosystems","Carbon cycle monitoring"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:45384"],"render_values":[{"text":"vt_gsexam:45384","href":null,"code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/10919/140839","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Wynne, Randolph H.","Thomas, Valerie Anne"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Huemmrich, Karl Fred"]},{"key":"dc:contributor.department","label":"Department","values":["Forest Resources and Environmental Conservation"]},{"key":"dc:creator","label":"Author","values":["Harmon, Caleb Sloan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-01-16T09:00:32Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-01-16T09:00:32Z"]},{"key":"dc:date.issued","label":"Date","values":["2026-01-15"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Forestry"]},{"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":["Solar-induced chlorophyll fluorescence","PACE mission","Ocean Color Instrument","Hyperspectral vegetation indices","Enhanced Vegetation Index","Chlorophyll Index Red Edge","Gross Primary Productivity","Global terrestrial ecosystems","Carbon cycle monitoring"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"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":["vt_gsexam:45384"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/10919/140839"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Solar-induced chlorophyll fluorescence (SIF) serves as a direct remotely sensed indicator of photosynthetic activity, making it a valuable tool for assessing terrestrial productivity. However, the practical application of satellite-derived SIF is hindered by spatial resolution limitations and data gaps. The NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission presents an opportunity to overcome these challenges through its hyperspectral Ocean Color Instrument and globally distributed Land Vegetation Index (LANDVI) product suite. This study's primary contribution lies in demonstrating that PACE vegetation indices alone can reliably predict SIF from global retrievals obtained using data from the Copernicus Sentinel-5P Tropospheric Monitoring Instrument (TROPOMI), even in the absence of PACE BRDF and albedo products (and their associated corrections). Using 8-day global composites from 2024, we establish a temporal and spatial correlation between PACE indices and TROPOMI SIF (TROPOSIF) across fifteen biome-stratified study regions, including forests, grasslands, agricultural systems, and xeric landscapes. Simple univariate linear models reveal that the Enhanced Vegetation Index (EVI) and the Chlorophyll Index Red Edge (CIRE) are the most reliable global predictors of SIF, accounting for 80% and 77% of the variance, respectively. Notably, the stability of the EVI-SIF and CIRE-SIF relationships across seasons further emphasizes the significant role of canopy structure and chlorophyll information captured by these two indices in explaining global SIF variability. Seasonal analyses indicate that while EVI and CIRE are most effective in most forests and agricultural systems, moisture-sensitive indices and pigment indices perform better during dry seasons and transitional periods in water-limited ecosystems. Spatial residual analyses suggest minimal global bias but systematic underestimation in boreal forests and selected tropical regions, which aligns with established effects of canopy architecture and fluorescence escape probability. Considering that EVI, in particular, is available even from moderate-resolution Earth resource satellite missions such as Sentinel-2 and Landsat, there is substantial potential for SIF downscaling to management and policy-relevant scales."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["New satellite technology from NASA's PACE mission helps us study Earth's plants from space. This project uses PACE data to measure how much plants glow faintly when they photosynthesize, a process called SIF, which shows how active and healthy plants are worldwide. By combining PACE data with information about different landscapes, like forests and grasslands, we created a way to predict this plant glow across the globe. Our findings show that certain measurements, like the greenness of plants, strongly match the glow, especially when looking at seasonal changes, plants behave differently in spring versus winter, for example. These results could help us monitor how plants respond to climate change, improve farming, and better understand how plants store carbon, which is vital for a healthy planet."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["From Hyperspectral Indices to Global Fluorescence: PACE Vegetation Indices as Predictors of Terrestrial Photosynthesis"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Wynne, Randolph H.","Thomas, Valerie Anne"],"dc:contributor.committeemember":["Huemmrich, Karl Fred"],"dc:contributor.department":["Forest Resources and Environmental Conservation"],"dc:creator":["Harmon, Caleb Sloan"],"dc:date.accessioned":["2026-01-16T09:00:32Z"],"dc:date.available":["2026-01-16T09:00:32Z"],"dc:date.issued":["2026-01-15"],"dc:description.abstract":["Solar-induced chlorophyll fluorescence (SIF) serves as a direct remotely sensed indicator of photosynthetic activity, making it a valuable tool for assessing terrestrial productivity. However, the practical application of satellite-derived SIF is hindered by spatial resolution limitations and data gaps. The NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission presents an opportunity to overcome these challenges through its hyperspectral Ocean Color Instrument and globally distributed Land Vegetation Index (LANDVI) product suite. This study's primary contribution lies in demonstrating that PACE vegetation indices alone can reliably predict SIF from global retrievals obtained using data from the Copernicus Sentinel-5P Tropospheric Monitoring Instrument (TROPOMI), even in the absence of PACE BRDF and albedo products (and their associated corrections). Using 8-day global composites from 2024, we establish a temporal and spatial correlation between PACE indices and TROPOMI SIF (TROPOSIF) across fifteen biome-stratified study regions, including forests, grasslands, agricultural systems, and xeric landscapes. Simple univariate linear models reveal that the Enhanced Vegetation Index (EVI) and the Chlorophyll Index Red Edge (CIRE) are the most reliable global predictors of SIF, accounting for 80% and 77% of the variance, respectively. Notably, the stability of the EVI-SIF and CIRE-SIF relationships across seasons further emphasizes the significant role of canopy structure and chlorophyll information captured by these two indices in explaining global SIF variability. Seasonal analyses indicate that while EVI and CIRE are most effective in most forests and agricultural systems, moisture-sensitive indices and pigment indices perform better during dry seasons and transitional periods in water-limited ecosystems. Spatial residual analyses suggest minimal global bias but systematic underestimation in boreal forests and selected tropical regions, which aligns with established effects of canopy architecture and fluorescence escape probability. Considering that EVI, in particular, is available even from moderate-resolution Earth resource satellite missions such as Sentinel-2 and Landsat, there is substantial potential for SIF downscaling to management and policy-relevant scales."],"dc:description.abstractgeneral":["New satellite technology from NASA's PACE mission helps us study Earth's plants from space. This project uses PACE data to measure how much plants glow faintly when they photosynthesize, a process called SIF, which shows how active and healthy plants are worldwide. By combining PACE data with information about different landscapes, like forests and grasslands, we created a way to predict this plant glow across the globe. Our findings show that certain measurements, like the greenness of plants, strongly match the glow, especially when looking at seasonal changes, plants behave differently in spring versus winter, for example. These results could help us monitor how plants respond to climate change, improve farming, and better understand how plants store carbon, which is vital for a healthy planet."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:45384"],"dc:identifier.uri":["https://hdl.handle.net/10919/140839"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Solar-induced chlorophyll fluorescence","PACE mission","Ocean Color Instrument","Hyperspectral vegetation indices","Enhanced Vegetation Index","Chlorophyll Index Red Edge","Gross Primary Productivity","Global terrestrial ecosystems","Carbon cycle monitoring"],"dc:title":["From Hyperspectral Indices to Global Fluorescence: PACE Vegetation Indices as Predictors of Terrestrial Photosynthesis"],"dc:type":["Thesis"],"thesis:degree_discipline":["Forestry"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:16Z"}