Which Sentinel-1 band should I use?

Modified on Wed, 19 Jul 2023 at 03:52 PM

TABLE OF CONTENTS



What is Sentinel-1?

  • Sentinel 1 is a C-band radar imaging system, operated by the European Space Agency
  • It provides global data every 12 days.
  • The first Sentinel 1 data is from 17th October 2014 until the present day.
  • All the S1 data in Earth Blox are derived from Interferometric Wide Swath mode. This means the spatial resolution is 20x20m.  (Note: the grid spacing of the pixels is 10x10m, but the resolution is still 20x20m.)



So which bands should I use?


There are two factors that you want to consider when deciding - Polarisation and Units.


Polarisation

  • Polarisation is the choice between HH, HV, VV, and VH.
    • Radar signals can be transmitted or received as either horizontal (H) or vertical (V) waves. For instance, the HH channel is both transmitting and receiving in H, whereas the HV channel is transmitting H and receiving in V. (the "cross-polarisation").
  • Sentinel 1 is a little more complicated.
  • In the Polar regions, the satellite collects HH and HV. This is because HH gives better contrast between sea ice and open water.
  • Everywhere else it collects VV and VH.  
  • See the map below for more information on the specific coverage of each polarisation.
  • When using Sentinel 1, for most uses either VV or VH will be the best option to select.


Units

  • The units option allows you to choose between dB and DN, which refer to the way the image is scaled.
  • DN=digital number, which is the linear scaling of the radar data. 
  • dB=deciBels, which is a logarithmic scaling of the data and often makes it easier to see the features in the image.


Sentinel-1 Coverage Map


The map below shows the coverage of the different polarisations of Sentinel-1, from August 2022 onwards. To see more information about the coverage, including historical coverage, you can find more information on the European Space Agency website.


Source: European Space Agency 



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