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Background

The Satellite Needs Working Group (SNWG)-2016 process supported the production of a global Harmonized Landsat and Sentinel-2 (HLS) surface reflectance product, reducing differences between each sensor and providing global observations on a common set of grids to expedite processing and analysis. Surface reflectance information is routinely used to assess vegetation type, long-term changes in land use, disasters, and season health as inferred through vegetation greenness. This information is obtained through "vegetation indices" that relate multiple HLS bands to specific parameters of interest as an instantaneous value, time series, or anomaly. The following indices are sought by the SNWG agencies: Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Soil-Adjusted Vegetation Index (SAVI), Modified Soil-Adjusted Vegetation Index (MSAVI), Normalized Difference Moisture Index (NDMI), Normalized Burn Ratio (NBR), Normalized Burn Ratio-2 (NBR2), and Triangular Vegetation Index (TVI). Indices will be generated for the HLS archive (December 2015 for Sentinel-2 and April 2013 for Landsat) and will continue forward with future HLS acquisitions as part of the HLS production system thereby increasing overall product efficiency while decreasing product latency and reducing duplicative processing efforts across the United States (U.S.) government.  

Status

This activity began implementation in fall 2023. Normalized Difference Water Index (NDWI) will be added to the vegetation indices suite at the request of SNWG agencies. Data from Sentinel-2C will be incorporated in 2024.

Solution Characteristics

PlatformsTemporal FrequencyHorizontal ResolutionGeographic DomainLatencySpectral BandThematic Areas
Landsat 8, Landsat 9, Sentinel-2 A, Sentinel-2 B, Sentinel-2 C2-3 days30 mGlobal2-3 daysVisible (VIS), Near Infrared (NIR), Short-wave Infrared (SWIR)Carbon Cycle and Ecosystems, Earth Surface and Interior, Land Cover and Land Use Change, Water and Energy Cycle

Societal Impact

The HLS-Vegetation Indices (VI) solution is a suite of 9 vegetation indices derived from HLS data products and is slated to be operational in fiscal year (FY) 2025. Similar to HLS data, the HLS-VI products benefit from 2-3 day latency and provide key data for global monitoring of vegetation health, soil properties, and water levels.

Solution Resources

Need help using solution? SNWG's Stakeholder Engagement Program (SEP) curates relevant training resources focused on how to access and use SNWG solutions. For each solution, resources are aggregated into the following categories: Fundamentals of Remote Sensing, Missions and Instruments, Data Products and Descriptions, Data Access and Code Examples, and Use Case and Application Examples. Information on workshops and open meetings are also included. The resources below are for the HLS-VI product. 

 

Training Resources

TopicResourceDescription
Fundamentals of Remote SensingWeb resource that provides information about phenology, both ground-based and via remote sensing
The Role of Remote Sensing in Vegetation StudiesAn overview of remote sensing and how it can be used for studying vegetation
HLS OverviewOverview of the Harmonized Landsat Sentinel-2 (HLS) Project
Harmonized Landsat Sentinel-2: A Harmonized Surface Reflectance ProductBackground on the HLS Processing Algorithms and Data Products
Understanding Phenology with Remote SensingTraining on the use of NASA remote sensing data for mapping vegetation health and seasonal patterns
TopicResourceDescription
Missions and InstrumentsLandsat ScienceOverview of the Landsat mission series that is used in the development of the Harmonized Landsat and Sentinel-2 (HLS) products
Sentinel-2 Mission GuideDetails of the Sentinel-2 mission
Landsat with Sentinel: Global CoverageVisualizations of the combined orbits of Landsat 8/9 and Sentinel-2
TopicResourceDescription
Data Products and DescriptionsHLSS30Data set landing page for the HLS Sentinel-2 Multi-spectral Instrument Surface Reflectance Daily Global 30m (HLSS30) product used in the production of HLS-VI
HLSL30Data set landing page for the HLS Operational Land Imager Surface Reflectance and TOA Brightness Daily Global 30m (HLSL30) product used in the production of HLS-VI
Landsat Surface Reflectance-derived Spectral IndicesInformation about Landsat-derived spectral indices
TopicResourceDescription
Data Access and Code ExamplesEarthdata Search HLS Data CollectionsList of HLS data collections from Earthdata Search
Data - Harmonized Landsat Sentinel 2Provides information on ways to access Harmonized Landsat and Sentinel-2 (HLS) data and includes information on the HLS Vegetation Index Suite
Data Prep ScriptsPython and/or R scripts available for downloading data and performing basic data processing functions
TopicResourceDescription
Use Case and Application ExamplesHarmonized Landsat 8 and Sentinel-2 Time Series Data to Detect Irrigated Areas: An Application in Southern ItalyUse of images from the HLS dataset to map the extent of irrigated areas in Southern Italy
Harmonized Landsat 8 and Sentinel-2 DataVisualizations of harmonized Landsat 8 and Sentinel-2 NDVI data
Weekly cloud free Harmonized Landsat Sentinel (HLS) Normalized Difference Vegetation Index (NDVI) estimates for western United States (2016-2019)Weekly cloud-free Harmonized Landsat and Sentinel-2 (HLS) Normalized Difference Vegetation Index (NDVI) estimates from 2016 to 2019 for mapping ecological conditions in the western United States
Exploring NASA's Harmonized Landsat and Sentinel-2 Dataset to Monitor Deforestation in the Amazon RainforestUse of HLS to monitor deforestation in the Amazon Rainforest using NDVI, EVI, Global Environmental Monitoring Index (GEMI), and SAVI vegetation indices
Spectral Indices for Land and Aquatic ApplicationsNASA Applied Remote Sensing Training Program (ARSET) tutorial for calculating spectral indices from Landsat 9 Operational Land Imager-2 (OLI-2), Sentinel-2 MultiSpectral Instrument (MSI), and Harmonized Landsat and Sentinel-2 (HLS) data

 

Workshops and Open Meetings

Title and Registration LinkDescriptionDate
ARSET - Spectral Indices for Land and Aquatic ApplicationsThis training will provide an overview of spectral indices for land and aquatic applications. Specifically, this training will begin with an introduction to the Normalized Difference Vegetation Index (NDVI), along with its calculation, uses, and prominence in Earth science. In session two, ARSET will expand to other spectral indices primarily used in aquatic ecosystems, such as the Normalized Difference Chlorophyll Index (NDCI), Normalized Difference Aquatic Vegetation Index (NDAVI), Floating Algal Index (FAI), and Normalized Difference Turbidity Index (NDTI) for aquatic applications. In the final session ARSET will review additional land-based indices such as the Enhanced Vegetation Index (EVI), Soil-Adjusted Vegetation Index (SAVI), and Normalized Burn Ratio (NBR). Not only will these sessions discuss the correct circumstances under which to use these indices, but participants will also take part in hands-on indices calculation over relevant study areas. Learners will work with data from Landsat 9 OLI-2, Sentinel-2 MSI and Harmonized Landsat Sentinel-2 (HLS) for indices calculation. The training will also discuss pre-calculated index products such as Terra Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices and HLS vegetation indices suite and upcoming data products available based on user feedback provided to the Satellite Needs Working Group. Use cases from recent Earth Action projects (such as NASA Digital Earth Virtual Environment and Learning Outreach Program (DEVELOP)) will further highlight how spectral indices can provide essential information about land and aquatic environments.October 26, 2023