Synthetic Aperture RADAR (SAR) Remote Sensing Basics and Applications

This post will provide an overview of the basics of Synthetic Aperture RADAR (SAR) and applications. The main topics discussed in the listed documents include: SAR basics, backscatter, geometry, interferometry, polarimetry, SAR data, data acquisition, available data sets/access to data, data analysis tools, future missions and SAR applications.

What is RADAR? – RAdio Detection And Ranging
What is SAR? – Synthetic Aperture Radar – Synthetic Aperture Radar (SAR) is an active remote sensing technology that uses microwave energy to illuminate the surface. The system records the elapsed time an d energy of the return pulse received by the antenna.


Synthetic Aperature Radar (SAR) Tutorials

  1. A Tutorial on Synthetic Aperture RADAR – ESA (PDF )  (PDF) (Radiometric Calibration of SAR Image)
  2. The Canada Centre for Mapping and Earth Observation (CCMEO) is considered an international leader in the development and use of synthetic aperture radar or SAR sensors.  From space, SAR can image the Earth’s surface through clouds and in total darkness.  This makes it a tremendously useful sensor for monitoring Canada’s changing landmass and coastal zones. CCMEO scientists have worked with the Canadian Space Agency in the development of both RADARSAT 1 and RADARSAT 2  satellite missions.  Their research has led to improved data quality through enhanced sensor design and post-launch calibration and validation activities.
  3. This training manual introduces and explains Interferometric Synthetic Aperture Radar (InSAR), including applications for data from the Envisat ASAR sensor and how to combine Envisat and ERS images to produce interferograms and differential interferograms.
  4. Synthetic Aperture RADARs Imaging Basics (PDF)
  5. NOAA SAR Manual (PDF)
  6. Synthetic-aperture imaging from high-Doppler-resolution measurements (PDF)
  7. A Mathematical Tutorial on Synthetic Aperture RADAR (PDF)
  8. Remote sensed ground control points with TerraSAR-X and TanDEM-X (PDF)

Synthetic Aperature Radar (SAR) Applications

  1. Infrastructure Monitoring with Spaceborne SAR Sensors (Link)
  2. Soil Moisture Measurements by SAR (PDF)
  3. Marine applications: Sea Ice (Link), Marine Winds (PDF), Oil Pollution (PDF)
  4. Land deformation (Link)
  5. Flood Mapping (PDF) (PDF)

Detecting rainfall from the bottom up: SM2RAIN

SM2RAIN is a simple algorithm for estimating rainfall from soil moisture data.

The SM2RAIN code and the soil moisture derived rainfall data sets are freely available and can be downloaded here. The description of SM2RAIN and of its performance can be found in Brocca et al. (2013) and Brocca et al., 2014. (also here at IRPI-CNR website)


Here you can find two recent TALKS (IPWG 2016SMAP 2016) showing the latest results with the applications of SM2RAIN to multiple satellite soil moisture products (ASCAT, QUIKSCAT, RAPIDSCAT, AMSR-E, AMSR2, SMOS, and SMAP). In the paper by Massari et al. (2014) it is shown that SM2RAIN-derived rainfall from in-situ soil moisture observations even improves flood modelling (see also here, Italian media). In this paper by Brocca et al. (2015) the application of SM2RAIN to synthetic and in situ observations at several sites in Europe further underlines the robustness of the method. In Ciabatta et al. (2015) the integration of SM2RAIN with state-of-the-art products has provided significant improvements for rainfall estimation over the whole Italian territory. The latest application of SM2RAIN is for irrigation assessment, see here the project and a first overview paper.
Other scientist are using SM2RAIN in Mexico, in the Tibet Pleateau, and on a global scale. Click on the image below for the current list (PDF) of SM2RAIN papers with link to full text.

ERS SAR data available via ESA On-The-Fly service – Content – Earth Online – ESA

ESA is pleased to announce that SAR data from the ERS-1 and the ERS-2 missions have been made available for direct download via the (A)SAR On-The-Fly (OTF) service.

With this release, users now have access to (A)SAR level 1 products from both ERS missions and from Envisat, covering Image Mode (IMS, IMP), Wide Swath (WSS) and Alternating Polarisation (APP, APS). All data are delivered as standard scenes in Envisat format.

Processing and download of the generated “standard scene” Level 1 products is performed directly through the EOLI-SA user interface. A user manual and FAQ page are available to get started.


Source: ERS SAR data available via ESA On-The-Fly service – Content – Earth Online – ESA

Satellite remote sensing data for hydrological analyses and water resources management

Satellite remote sensing data for hydrological analyses and water resources management are listed below:

  1. Groundwater Discharges: Researcher uses satellite data to analyze the groundwater discharges. Locating ground-water discharge areas
  2. Land Water Boundaries: Satellite data has been used to convert surface features into land cover maps including water body. Water body detection and delineation with Landsat TM data
  3. Management of Water: Satellite images has important use in water management. The USA government agencies are using satellite data for monitoring decreasing water resources, especially in western part of USA by estimating past and present water use and evapotranspiration (ET). The Landsat program and water resources information needs in the United States
  4. Monitoring Flooding: Satellite image are in use to map flood damage area. Case studies
  5. Monitoring Lakes: Satellite data helps to understand and monitor changes in lake water volume (snow melt) and quality (due to spring run-off). Monitoring lake inventories and health
  6. Watersheds Mapping: Satellite data are used to map the watersheds area. Determining land use change within the dog river watershed
  7. Wetlands: Landsat data can be downloaded of few decades back, so it can be used to track the number and area of the wetlands. Mapping wetlands and riparian areas