Processing Levels

Level-1C

Level-1C product provides orthorectified Top-Of-Atmosphere (TOA) reflectance, with sub-pixel multispectral registration. Cloud and land/water masks are included in the product.

Level-2A

Level-2A product provides orthorectified Bottom-Of-Atmosphere (BOA) reflectance, with sub-pixel multispectral registration. A Scene Classification map (cloud, cloud shadows, vegetation, soils/deserts, water, snow, etc.) is included in the product.

The Level-2A operational processor (Sen2Cor) generates Level-2A (BOA reflectance) products from Level-1C products. This processing is split into two parts:

  • Scene Classification (SC) algorithm aims at providing a pixel classification map

  • Atmospheric Correction (S2AC) aims at transforming TOA reflectance into BOA reflectance.

From the mid-March 2018, the Level-2A became an operational product, beginning with coverage of the Euro-Mediterranean region. Global coverage started in December 2018.

S2 levels

Sentinel-2 processing levels. Only Level-1C and Level-2A products (in green) are made available to users

Level-1C and Level-2A are projected onto a UTM/WGS84 grid and made available publicly on 100x100 km tiles. Each tile has a unique ID. Take a look on the Sentinel-2 UTM tiling grid by clicking here !

S2 tiles

Sentinel-2 tiles in Belgium. Three tiles cover the majority of the Belgian territory: 31UES, 31UFS and 31UFR

Spectral bands & spatial resolution

The spatial resolution of Sentinel-2 is dependent on the particular spectral band.

10m spatial resolution

20m spatial resolution

60m spatial resolution

B2 (490 nm)

B5 (705 nm)

B1 (443 nm)

B3 (560 nm)

B6 (740 nm)

B9 (940 nm)

B4 (665 nm)

B7 (783 nm)

B10 (1375 nm)

B8 (842 nm)

B8a (865 nm)

B11 (1610 nm)

B12 (2190 nm)

S2 bands

Data Formats

Sentinel-2 products are made available to users in SENTINEL-SAFE format, including image data in JPEG2000 format, quality indicators (e.g. defective pixels mask), auxiliary data and metadata.

The SAFE format has been designed to act as a common format for archiving and conveying data within ESA Earth Observation archiving facilities. The SAFE format wraps a folder containing image data in a binary data format and product metadata in XML. This flexibility allows the format to be scalable enough to represent all levels of SENTINEL products.

A Sentinel-2 product refers to a directory folder that contains a collection of information. It includes:

  • a manifest.safe file which holds the general product information in XML

  • a preview image in JPEG2000 format

  • subfolders for measurement datasets including image data (granules/tiles) in GML-JPEG2000 format

  • subfolders for datastrip level information

  • a subfolder with auxiliary data (e.g. International Earth Rotation & Reference Systems (IERS) bulletin)

  • HTML previews

The Level-2A prototype product is an orthorectified product providing Bottom-Of-Atmosphere (BOA) reflectances, and basic pixel classification (including classes for different types of cloud).

The Level-2A image data product uses the same tiling, encoding and filing structure as Level-1C.

The Level-2 product is also in SAFE format, which groups together several types of file:

  • metadata file (XML file)

  • preview image (JPEG2000 with GML geo-location)

  • tiles files with BOA reflectances image data file (GML / JPEG2000) for each tile

  • datastrip files

  • auxiliary data

  • ancillary data (Ground Image Processing Parameters (GIPPs))

SAFE folder

Note

Before starting this notebook, you should download Sentinel-2 Level-2A products. The L2A products are downloadable by tiles which are 100x100 km ortho-images in UTM/WGS84 projection.