Readily available, no-charge data gathered by Landsat 7's Enhanced Thematic Mapper Plus (ETM+) sensor can also be used to generate NDVI image products (see Table 1). With a resolution of 30 m, ETM+ data can be transformed into NDVI images that have greater spatial detail than those derived from AVHRR, but which cover a smaller area. Furthermore, Landsat's orbit repeats every 16 days, compared to AVHRR's daily coverage. This makes creating cloud-free NDVI products from ETM+ data more challenging.
Another modern, well-calibrated, daily, moderate-resolution satellite sensor with the proper instrumentation for studying vegetation greenness is the Moderate Resolution Imaging Spectroradiometer (MODIS) carried aboard National Aeronautics and Space Administration (NASA) Terra and Aqua satellites. Global MODIS data are also readily available for no charge, and are high-quality input for vegetation time-series analysis. MODIS data are routinely transformed into vegetation index, NDVI, and enhanced vegetation index (EVI) image products with 250-m, 500-m, and 1-km spatial resolution.
Below are other science projects associated with this project.
NDVI from AVHRR
NDVI, the Foundation for Remote Sensing Phenology
- Overview
Readily available, no-charge data gathered by Landsat 7's Enhanced Thematic Mapper Plus (ETM+) sensor can also be used to generate NDVI image products (see Table 1). With a resolution of 30 m, ETM+ data can be transformed into NDVI images that have greater spatial detail than those derived from AVHRR, but which cover a smaller area. Furthermore, Landsat's orbit repeats every 16 days, compared to AVHRR's daily coverage. This makes creating cloud-free NDVI products from ETM+ data more challenging.
Sources/Usage: Public Domain.Fall foliage colors are visible in this 9 October 2001 MODIS image of New England. Photo courtesy of NASA's Earth Observatory. Another modern, well-calibrated, daily, moderate-resolution satellite sensor with the proper instrumentation for studying vegetation greenness is the Moderate Resolution Imaging Spectroradiometer (MODIS) carried aboard National Aeronautics and Space Administration (NASA) Terra and Aqua satellites. Global MODIS data are also readily available for no charge, and are high-quality input for vegetation time-series analysis. MODIS data are routinely transformed into vegetation index, NDVI, and enhanced vegetation index (EVI) image products with 250-m, 500-m, and 1-km spatial resolution.
- Science
Below are other science projects associated with this project.
NDVI from AVHRR
The sensor responsible for the longest running series of NDVI products used for large-area phenology studies is carried aboard National Oceanic and Atmospheric Administration (NOAA) polar-orbiting weather satellites (see Table 1). This sensor, known as the Advanced Very High Resolution Radiometer (AVHRR), has a daily repeat cycle and, despite its name, a 1-km resolution (an AVHRR image pixel...NDVI, the Foundation for Remote Sensing Phenology
Remote sensing phenology studies use data gathered by satellite sensors that measure wavelengths of light absorbed and reflected by green plants. Certain pigments in plant leaves strongly absorb wavelengths of visible (red) light. The leaves themselves strongly reflect wavelengths of near-infrared light, which is invisible to human eyes. As a plant canopy changes from early spring growth to late...