Level-1C

Sentinel-2 MSI User Guide - Level-1C Product Type

The Level-1C product is composed of 110x110 km2 tiles (ortho-images in UTM/WGS84 projection). Earth is subdivided on a predefined set of tiles, defined in UTM/WGS84 projection and using a 100 km step. However, each tile has a surface of 110x110 kmĀ² in order to provide large overlap with the neighbouring. The Level-1C product results from using a Digital Elevation Model (DEM) to project the image in cartographic geometry. Per-pixel radiometric measurements are provided in Top Of Atmosphere (TOA) reflectances along with the parameters to transform them into radiances. The formula for the conversion of reflectance to radiance is:

radiance = reflectance * cos(radians(SunZenithAngle)) * solarIrradiance * U / pi

Understanding:

  1. The value of SunZenithAngle can be found in the tile metadata
  2. The value of U and SolarIrradiance for the considered band can be found in the End User  Product metadata

NOTE: In order  to undertake this conversion, the User will first need to convert the digital counts into reflectance.

Level-1C products are resampled with a constant Ground Sampling Distance (GSD) of 10, 20 and 60 m depending on the native resolution of the different spectral bands. In Level-1C products, pixel coordinates refer to the upper left corner of the pixel.

Please note that starting with 25 January 2022 (PB 04.00), to avoid truncation of negative values, the dynamic range of Level-1C products is shifted by a band-dependent constant radiometric offset called RADIO_ADD_OFFSET. The value of this offset is available in the product metadata.

Moreover, independent validation analysis highlighted that SENTINEL-2A shows brighter TOA-reflectance than SENTINEL-2B, with an average bias of 1.1% over the VNIR bands. As the SENTINEL-2A reflectance is known to be close to those of other sensors such as OLI/LANDSAT-8, MERIS, SPOT-5, a re-adjusting of the native reflectance of SENTINEL-2B by a factor 1.011 for all the VNIR bands was implemented within the PB 04.00.

Level-1C products dditionally include quality information like Cloud Masks, and auxiliary data like ECMWF data (total column of ozone, total column of water vapour and mean sea level pressure) and CAMS (Copernicus Atmosphere Monitoring Service) aerosols content information.

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Key Resources

Sentinel-2 MSI User Guide Key Resources