Synthetic Aperture Radar: Ecosystems

Remote sensing observations have become an essential tool in observing the state and evolution of the earth’s ecosystems. They are a unique means within earth sciences to gain an immediate and regional- to continental-scale view of the earth environment, allowing for the monitoring and change detection of entire biomes over time.

This course will introduce you to Synthetic Aperture Radar (SAR), a remote sensing technology that can see the earth surface even during darkness and through rain, clouds, or smoke. As a participant in this course, you will learn how the weather-independence of SAR combined with its ability to penetrate into vegetation canopies make SAR an excellent information source to characterize vegetation structure, measure above-ground biomass, and analyze the change of vegetation long term and throughout the seasons. Each SAR ecosystem application will be illustrated with relevant data sets and hands-on exercises. Specific topics include:

• The concepts and principles of SAR and polarimetric SAR
• How to access and visualize SAR data and SAR imagery
• Interpretation of SAR images at different wavelengths and polarizations in the context of ecosystems monitoring
• The use of SAR techniques in monitoring forest degradation
• Techniques for estimating forest biomass through SAR earth observation
• The application of SAR to the monitoring of agriculture extent
• The learned concepts will be put into action in using SAR time series data sets from spaceborne SAR missions over agriculture sites and forested regions undergoing degradation. Learners registered for the verified track will additionally get the opportunity for hands-on lab exercises and tutorials using Jupyter Notebooks. The verified track will also include peer discussions and a verified certificate upon successful completion.

This course is produced by the Alaska Satellite Facility at the University of Alaska Fairbanks, which has been selected as the NASA data hub for the upcoming NISAR mission.

Week 1: Contribution of SAR to Monitoring forests

This first section will provide an overview of the capabilities of SAR. We will discuss how using the SAR backscatter power can create images of the surface at all weather conditions and during night and day. We will discuss how different SAR signals can penetrate through vegetation to reveal what's beneath.

We will also discuss how we can use the polarimetric capabilities of SAR to analyze vegetation covers, agriculture, and above-ground biomass.

• Introduce yourself and join the SAR course learning community
• Overview basic principles of imaging radar
• Look at polarimetric radar for ecosystem applications
• The contribution of SAR to forest monitoring

Week 2: SAR for Agriculture Monitoring

• Radar backscatter from crops
• SAR signatures of selected crops
• Picking the optimal sensor wavelength
• Mapping crop area extent using SAR

Week 3: Forest Degradation / Deforestation using SAR remote sensing

• Forest degradation and deforestation
• Forest change examples
• Introduction to Google Earth engine
• Lab: Mapping Deforestation (open to audit track)
• Lab: SAR Point Time Series Over Deforestation Sites (verified track only)

Week 4: Biomass estimation using SAR

• SAR-based biomass estimation
• SAR processing steps for biomass estimation
• SAR biomass estimation algorithms