The free digital tool integrates Google Earth Engine with high-resolution imagery from the European Space Agency's Copernicus Sentinel-2 satellite mission, consisting of two identical satellites that share the same orbit. The Sentinel GreenReport Plus combines this satellite imagery with climate datasets from the PRISM group. As a public-service resource, the tool provides users with up-to-the-day insights into vegetation greenness, changes in land cover over time and climate abnormalities.
According to its KU creators, the Sentinel GreenReport Plus already has seen use in monitoring crops, assessing damage from drought, detecting changes in land use and tracking vegetation recovery following a disaster.
"Remote sensing and satellite imagery technology has been improving in terms of the spatial footprint that it can represent in a pixel," said Dana Peterson, director of KansasView and senior research associate with Kansas Applied Remote Sensing, a program of the Kansas Biological Survey and Center for Ecological Research at KU. "This allows us to do more detailed monitoring of vegetation condition - it could be vegetation in a forest community, a cropland community or on rangeland. We could create a tool that would allow access to these data easily and create an interface where people - whether educators, researchers, ranchers or cropland producers - could access the imagery easily and look at vegetation health."
The KU team said the public-facing digital tool could be used further to assess vegetation destruction from natural hazards or even more routine damage like hail.
"We've also looked at some of the burn events and wildfires," Peterson said. "You can look at how the vegetation has been damaged and to what extent and severity."
The Sentinel GreenReport Plus improves detail and insight over the classic GreenReport, introduced in 1996 with support from NASA by the Kansas Applied Remote Sensing Program. The new Sentinel GreenReport Plus is underpinned by Copernicus Sentinel-2 satellite data, a much finer 10-meter resolution than the classic version relying on 1,000-meter resolution MODIS imagery.
Abinash Silwal, KU graduate student and tech lead in the project, said any agricultural producer could use the tools to assess the success of different crops, monitor crop health or compare crop conditions over time, which may indicate yield performance. The tool integrates USDA NASS Cropland Data Layers, which allows crop-specific stress analysis.
"We can look at vegetation health at the crop-type level," Silwal said. "For example, if I want to monitor my field of corn, I can select 'corn' in the app and draw a rectangle or polygon around the area. The tool instantly displays multiple charts, including a time series and comparison charts showing current vegetation health relative to historical averages. This helps determine whether the crop's current condition falls within the normal range or is showing signs of stress."
The heart of the Sentinel Green Report PLUS is underpinned by the Normalized Difference Vegetation Index. The Sentinel GreenReport PLUS has several key features:
Greenness Map: Uses the NDVI as a proxy for photosynthetically active plant biomass over a selected composite period.
Difference Map 1: Compares NDVI to the previous composite period within the same year, illustrating recent vegetation changes.
Difference Map 2: Compares NDVI to the same period from the previous year, highlighting year-over-year vegetation changes.
Difference Map 3: Compares current NDVI to the average NDVI from previous years, showing changes relative to historical trends.
Aside from Peterson and Silwal, the team that produced the Sentinel GreenReport Plus is composed of Chen Liang, former doctoral student; Jude Kastens, research associate professor and director of KARS; and Xingong Li, professor of geography and atmospheric science.
The KU researchers know stakeholders have found many features to be valuable. For instance, Silwal said the ability to compare vegetation health with precipitation adds a powerful dimension to understanding vegetation stress.
"The addition of the precipitation curve is the coolest thing," he said. "If I see that vegetation health is below normal and the precipitation curve is flat or shows significantly lower rainfall compared to the 30-year historical statistics, we can infer that drought may be contributing to the stress. When the vegetation line is declining and the accumulated precipitation trend remains flat or below average, it points to possible drought conditions affecting crop health."
These breakthroughs should lead to better-informed agricultural producers, policymakers, insurers and research ecologists in Kansas and across the nation, Peterson said.
She added the Sentinel GreenReport Plus might represent "a better way to understand the interplay of climate and vegetation. Users can visualize trends, generate crop-specific charts and download outputs to support reports, presentations and further analysis."
Research Report:Sentinel GreenReport Plus
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