Application-Ready Expedited MODIS Data for Operational Land Surface Monitoring of Vegetation Condition

Abstract

Monitoring systems benefit from high temporal frequency image data collected from the Moderate Resolution Imaging Spectroradiometer (MODIS) system. Because of near-daily global coverage, MODIS data are beneficial to applications that require timely information about vegetation condition related to drought, flooding, or fire danger. Rapid satellite data streams in operational applications have clear benefits for monitoring vegetation, especially when information can be delivered as fast as changing surface conditions. An "expedited" processing system called "eMODIS" operated by the U.S. Geological Survey provides rapid MODIS surface reflectance data to operational applications in less than 24 h offering tailored, consistently-processed information products that complement standard MODIS products. We assessed eMODIS quality and consistency by comparing to standard MODIS data. Only land data with known high quality were analyzed in a central U.S. study area. When compared to standard MODIS (MOD/MYD09Q1), the eMODIS Normalized Difference Vegetation Index (NDVI) maintained a strong, significant relationship to standard MODIS NDVI, whether from morning (Terra) or afternoon (Aqua) orbits. The Aqua eMODIS data were more prone to noise than the Terra data, likely due to differences in the internal cloud mask used in MOD/MYD09Q1 or compositing rules. Post-processing temporal smoothing decreased noise in eMODIS data.

Dynamics of Fractional Vegetation Coverage and Its Relationship with Climate and Human Activities in Inner Mongolia, China

“…NDVI is the best indicator of vegetation growth and correlates well with vegetation coverage [23]. According to the pixel dimidiate model, the NDVI of one pixel can be represented as NDVI veg and NDVI soil .…”

Normalized Difference Vegetation Index as an Estimator for Abundance and Quality of Avian Herbivore Forage in Arctic Alaska

“…We calculated two separate NDVI values using reflectance readings from handheld spectrometers: one based on band definitions for the "expedited" Moderate Resolution Imaging Spectroradiometer (eMODIS) imagery from the Terra satellite [43], and the other based on band definitions for the WorldView-2 satellite imagery. The band definitions for eMODIS NDVI were red = 616-674 nm and near infrared (NIR) = 837-880 nm; for WorldView-2 NDVI, the definitions were red = 630-690 nm and NIR = 770-895 nm.…”

Grassland and Cropland Net Ecosystem Production of the U.S. Great Plains: Regression Tree Model Development and Comparative Analysis

“…Currently, available flux towers grossly under sample the Great Plains ecosystems in both time and space relative to the mapped population (area × years) of this study. The 76 site years of flux tower data used to develop the NEP mapping models represented only 0.00003% of the space for time population that was mapped (28,817,873 pixels at 250 m resolution × 9 years). Particularly, limited flux tower representation occurs in cropland areas in the extreme northern, southern, and western portions of the U.S. Great Plains (Figure 1), where high RMSE values were observed (Figure 8).…”

“…NDVI is derived from visible and near-infrared (NIR) light reflectance measurements (Equation (1)) and correlates with the photosynthetic potential of vegetation [27]. The eMODIS NDVI product [26] is processed using the same data source and atmospheric correction algorithms as the standard MODIS collection 5 data product [28]. However, the eMODIS process uses a compositing algorithm which is largely dependent on maximum value-NDVI compositing, scan angle, and data quality flags to filter through input reflectance with bad quality, negative values, clouds, snow cover, or low view angles.…”