The Copernicus Sentinel-2 Collection-1 is presently being created over the Sentinel-2 historical archive to provide consistent Sentinel-2A and Sentinel-2B time series with a uniform processing baseline and optimised calibration, in particular improving, but not limited to, the products geometric performance. All historical data in the period spanning from the Sentinel-2A satellite launch back in 2015 until December 2021 are planned to be reprocessed.

The section “Collection-1 products features” below recalls the main anticipated features of Sentinel-2 Collection-1 products.

The related reprocessing activity, implemented by an industrial consortium ​  led by ACRI-ST, is planned to complete by Q4 2023.

This article aims at providing up-to-date progress information on the proceedings of the generation of Collection-1 and on the gradual availability of Collection-1 Level-1C and Level-2A products, under the form of a synthetic facts sheet as provided here below.

The Copernicus Data Space Ecosystem is the main distribution service for data from the Copernicus Sentinels missions. These data,including the Sentinel-2 Collection-1, are accessible via a series of APIs, as well as through a new, more intuitive browser interface, the Copernicus Browser.

​

Collection-1 data is distributed simultaneously though:

​	https://creodias.eu
​	https://www.onda-dias.eu
​	https://mundiwebservices.com

Last updated: 17/11/2023    

(*) The general availability figures reported refer to the readiness of the Collection-1 Level-1C and Level-2A products for downstream distribution at the DIAS(es). The actual products availability in the DIAS inventories may temporarily differ considering the time to ingest the products in the respective DIAS repositories.

Collection-1 Products Features

The Processing Baseline identifier 05.00  will tag every Sentinel-2 Collection-1 product issued from the reprocessing activity.

As part of the Sentinel-2 reprocessing campaign, the improvements introduced in recent processing baselines up to baseline 04 (in operations since 25 January 2022) will be generalised to the historical archive, namely:

• Geometric refining using the high-quality Copernicus Digital Elevation Model (introduced in Processing Baseline PB  03.00)
• Harmonized radiometry after alignment of S2B on S2A (introduced with PB 04.00)
• Most recent product format for L1C and L2A with radiometric offset, quality masks in raster format, L2A quality indicators, DOI (introduced in PB 04.00)
• Improved L2A processing algorithms for scene classification and surface reflectance (PB 04.00 feature)
• Compliance with the CEOS Analysis Ready Data for Land (CEOS ARD) standard of the Level-2A surface reflectance product (PB 04.00 feature).

Additional improvements are brought in Collection-1 products over the baseline 04:

• Corrected quality mask for radiometric saturation
• Identification of defective pixels from missing instrument source packets in the L2A Scene Classification layer

Finally, further enhancements are specifically applied in the frame of the reprocessing activity:

• Optimization of the applicability along-time of the successive radiometric and geometric calibrations 
• Use of the new 30 m Copernicus Digital Elevation Model (DEM), with corresponding improvement of the geolocation performance over mountainous areas in particular.  More details about the last DEM versions and how to access the data is available at https://spacedata.copernicus.eu/collections/copernicus-digital-elevation-model.

It is highlighted that the Level-1C and level-2A product format remains according to version 14.9 of the Product Specification Document (PSD v14.9).