Data access

spot-take5.org

Présentation

At the end of life of each satellite, CNES issues a call for ideas for short-term experiments taking place before de-orbiting the satellite. CESBIO took the opportunity to set up the Take 5 experiment at the end of SPOT4′ life : this experiment uses SPOT4 as a simulator to give us a hint of the time series that ESA’s Sentinel-2 mission will provide. 

On January 29 2013, the orbit has been lowered from SPOT4’s orbit by 3 kilometers to put it on a 5 day repeat cycle orbit, which means that the satellite has flied the same places on earth every 5 days. Spot4 has followed this orbit until the end of June 2013. During this period, 42 sites have been observed every 5 days, as in the case of Sentinel-2. The data are processed and distributed by Theia  and distributed to users by the end of June 2013.

Contact

theia-land@cnes.fr

Satellite

Name : Spot 4

Imaging mode : optical

Spectral bands : 

  • Green
  • Red
  • Near infrared
  • Moyen infrared

Resolutions : 20 m

Observation capability : 

  • Swath : 60 km
  • Revisit : 5 days

Coverage : 

  • Area : 45 sites in the world
  • Period : February to June 2013

For more information see spot.cnes.fr.

Level

Level 1C : data orthorectified reflectance at the top of the atmosphere

Level 2A : data ortho-rectified surface reflectance after atmospheric correction, along with a mask of clouds and their shadows, as well as a mask of water and snow

Format

Level 1C : Top of Atmosphere reflectance ortho-rectified product (updated for V2.0)

The  TAR file distributed by THEIA Land Data Center contains 2 files and a MASK directory.

The 2 files provide the following information :

  • the xml file provides the image metadata
  • a TIF file

The mask directory provides :

  • a saturated pixel mask _SAT.TIF, wIth an 8 bit information 

Level 2A : Surface reflectances and cloud mask

The  TAR file distributed by Theia contains 4 files and MASK directory :

 The 4 files provide the following information :

  •  An XML file (as in Level 1C)
  • Two .TIF files in GeoTiff format that provide surface reflectances, corrected from atmospheric effects, including adjacency effects (ORTHO_SURF_CORR_ENV, not provided for LANDSAT) and even terrain effects (ORTHO_SURF_CORR_PENTE)
  • the AOT TIF file provides the estimates of Aerosol Optical Thicknesses (AOT)

The mask directory provides :

  • A saturated pixels mask _SAT.TIF (as in Level 1C)
  • A mask of clouds and cloud shadows _NUA.TIF
  • Diverse binary masks : water, snow and no_data mask, plus (V2.0) pixels lying in terrain shadows _DIV.TIF

For more information, see Take5 Product Format

License

Licence Spot 4 (take5)