L1C & L2A

L1C Product

Sentinel-2 Level-1C product is composed of 110x110 km2 tiles (ortho-images in UTM/WGS84 projection) where per-pixel radiometric measurements are provided in Top Of Atmosphere (TOA) reflectances along with the parameters to transform them into radiances.

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.

Level-1C products additionally 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.

Sen2Chain processes are all applied on the Tile object, from downloading a L1C Product to computing radiometric indices.

To download a L1C Product on a given Tile, use Sen2Chain’s Tile.get_l1c() method :

from sen2chain import Tile
Tile('40KCB').get_l1c(provider="cop_dataspace", start="2023-01-01",end="2023-01-05")

L2A Product

Sen2chain allows you to choose between two methods to obtain L2A ; you can compute them from L1C images using Sen2cor according to your preference settings, or download the L2A produced by Copernicus directly.

Sen2Chain uses ESA’s Sen2cor processing chain to process Top-Of-Atmosphere Level 1C input data into L2A Surface Reflectance products.

Sen2Cor creates Bottom-Of-Atmosphere, optionally terrain- and cirrus corrected reflectance images; and additionally, Aerosol Optical Thickness-, Water Vapor-, Scene Classification Map and Quality Indicators for cloud and snow probabilities.

Its output product format is equivalent to the Level 1C User Product: JPEG 2000 images, with three different resolutions, 60, 20 and 10 m.

To process L1C products into L2A, call for compute_l2a() Tile’s method.

Tile('40KCB').compute_l2a(...)

To download L2A products directly, call for get_l2a() Tile’s method.

Tile('40KCB').get_l2a(...)