Abstract
Cross-sensor compatibility of spectral vegetation indices (VIs) between Suomi National Polar-orbiting Partnership Visible Infrared Imaging Radiometer Suite (VIIRS) and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) was investigated using their near-coincident observation pairs obtained along overlapped orbital tracks across the globe for the year 2015. The “top-of-atmosphere (TOA)” and “top-of-canopy (TOC)” normalized difference vegetation indices (NDVIs), TOC-enhanced vegetation index (EVI), and TOC two-band EVI (EVI2) were investigated. For all four VIs, VIIRS and MODIS VIs were subject to systematic differences in which VIIRS VIs were higher than their MODIS counterparts. The overall systematic differences and uncertainties (measured as mean differences and root mean square differences, respectively) were small (0.010 to 0.020 VI units and 0.015 to 0.022 VI units, respectively). TOA NDVI cross-sensor differences were neither seasonally nor view zenith angle dependent, whereas TOC NDVI cross-sensor differences slightly varied seasonally, but were not view zenith angle dependent. TOC EVI and TOC EVI2 cross-sensor differences were view zenith angle dependent, where systematic differences increased with increasing view zenith angle and, for large view zenith angles, they were higher during the summer seasons. These results support the normalization of view zenith angles as a required step to extend the MODIS VI record with VIIRS data.
Highlights
We extend the approach of Vargas et al.[15] and cross-compare Suomi National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices (VIs) using their near-coincident observation pairs collected for a wide range of view zenith angles across the globe for the year 2015
We investigated cross-sensor compatibilities of the four VIs between VIIRS and MODIS, namely TOA normalized difference vegetation indices (NDVIs), TOC NDVI, TOC enhanced vegetation index (EVI), and TOC EVI2, and the input reflectances using their near-coincident observation pairs obtained across the globe for the year 2015
All the four VIs from VIIRS and MODIS were subject to systematic differences
Summary
Spectral vegetation indices (VIs) have been used in a broad range of studies that involve an analysis of vegetation dynamics in regional-to-global scales, including climate–vegetation interactions, drought impact assessment, and land surface phenology.[1,2,3] VIs have been used successfully to estimate biophysical parameters, such as the fraction of photosynthetically active radiation, green vegetation fraction, leaf area index (LAI), and gross primary productivity (GPP).[4,5,6] The most widely used index is the normalized difference vegetation index (NDVI):[7,8]NDVI 1⁄4 ðρNIR − ρred Þ∕ðρNIR þ ρred Þ; EQ-TARGET;temp:intralink-;e001;116;179 (1)where ρNIR and ρred are the near-infrared (NIR) and red reflectances, respectively. Spectral vegetation indices (VIs) have been used in a broad range of studies that involve an analysis of vegetation dynamics in regional-to-global scales, including climate–vegetation interactions, drought impact assessment, and land surface phenology.[1,2,3] VIs have been used successfully to estimate biophysical parameters, such as the fraction of photosynthetically active radiation, green vegetation fraction, leaf area index (LAI), and gross primary productivity (GPP).[4,5,6] The most widely used index is the normalized difference vegetation index (NDVI):[7,8]. Long-term time-series data of the NDVI derived from the National Oceanic and Atmospheric. Administration (NOAA) Advanced Very High-Resolution Radiometer (AVHRR) sensor series (e.g., Ref. 9) have been used extensively to improve our understanding of climate–vegetation interactions in regional-to-global scales.[1,10].
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.