Sentinel-1

ESA active radar satellites

All Sentinels

• Download data at: Copernicus Open Access Hub (Directions)
• use SNAP
  • https://senbox.atlassian.net/wiki/spaces/SNAP/pages/1898053693/SNAP+FAQs
  • Download at: https://step.esa.int/main/
  • Insure that you start the installer as administrator (right click, open as administrator)
  •  Sentinel-1, SAR
    • Open manifest.safe
    • Display of bands is initially very slow (they are huge)
  •  Sentinel-2, MSI
    • Open MTD_MSIL1C.xml
  • Sentinel-3

Sentinel-1:

• User Guide:  https://sentinels.copernicus.eu/web/sentinel/user-guides/sentinel-1-sar/overview
• Technical Guide: https://sentinels.copernicus.eu/web/sentinel/technical-guides/sentinel-1-sar
• Sentinel Hub is good starting place to explore imagery
• https://asf.alaska.edu/how-to/data-recipes/geocode-sentinel-1-with-gdal/

https://www.l3harrisgeospatial.com/docs/sentinel1intensityanalysistutorial.html

• https://asf.alaska.edu/how-to/data-recipes/create-an-interferogram-using-esas-sentinel-1-toolbox/
  • Need to get sub_swath SLC burst mode, IW (each scene about 4 GB download, and 8 GB uncompressed)
  • May need to go to apply orbit file, and tell the program not to fail
• https://asf.alaska.edu/how-to/data-recipes/create-an-rgb-composite-from-multi-temporal-sentinel-1-data/

• GRD is not projected, because it is in ground range geometry (the .tiff in the SAFE set is not a GeoTIFF). You need to first apply terrain correction to project and create a GeoTIFF, which will then have the geometry information embedded in the relevant TIFF tags (which gdal.open() recognises).
  • GRD are about 0.75 GB compressed, and about 1.5 GB uncompressed
• Geocoding and terrain correction are different
• Multi-coherence product for volcanic eruptions
• StaMPS was developed by Hooper et al. (2004) to calculate PS-InSAR time series. Hooper, A., Zebker, H., Segall, P., & Kampes, B. (2004). A new method for measuring deformation on volcanoes and other natural terrains using InSAR persistent scatterers. Geophysical Research Letters, 31(23). https://doi.org/10.1029/2004gl021737
• Modes
  • Stripmap (SM) 80 km swath, slightly better than 5x5 m spatial resolution.  Image small islands and in exceptional cases emergency operations
  • Interferometric Wide (IW) swath mode is the main acquisition mode over land and satisfies the majority of service requirements. 250 km swath at 5 m by 20 m spatial resolution
  • Extra Wide (EW) swath mode  acquires data over a 400 km swath at 20 m by 40 m spatial resolution.
  • Wave mode acquires data in 20 km by 20 km vignettes, at 5 m by 5 m spatial resolution, every 100 km along the orbit, acquired alternately on two different incidence angles.   Wave mode at VV polarisation is the default mode for acquiring data over open ocean.

Radar principles

• Rough surface reflects more back to the sensor
• Dielectric constant
  • Most materials 3-8
  • Water approximately 80, so moisture greatly increases reflectivity

Color scaling

https://gis.stackexchange.com/questions/400726/creating-composite-rgb-images-from-sentinel-1-channels

• composite RGB (colour) image created using the VV channel for red, VH channel for green and the ratio |VV| / |VH| for blue.

• First of all, the RGB combination to achieve something similar to the map you showed is:

  • red=VV
  • green=VH
  • blue=VV/VH

  if you work with linear data.

  If you work with log-scaled data (in dB) it is slightly different because the laws of logarithms which turn ratios into subtraction:

  • red=VV
  • green=VH
  • blue=VV - VH

Last revision 6/25/2022