Sentinel-2 snow products for all INARCH basins

Level 2B products (L2B)
Sentinel-2 level 2B snow products have a 5-day revisit and a spatial resolution of 20 m.

LIS_S2-SNOW-FSC*.tif provides the fractional snow cover:

0: No-snow
]0-100]: Snow cover fraction in percent
205: Cloud including cloud shadow
255: No data (permanent water bodies are classified as nodata)
LIS_S2-SNOW-FSC-QCFLAGS*.tif provides quality flags for more expert users:

bit 0: MAJA sun too low for an accurate slope correction
bit 1: MAJA sun tangent
bit 2: water mask
bit 3: tree cover density > 90%
bit 4: snow detected under thin clouds
bit 5: tree cover density undefined or unavailable
bit 6: FSC in shaded slope set to 100
The filename of the product indicates the acquisition time in UTC. For example LIS_S2-SNOW-FSC_T11UNT_20170704T185934_1-10_01.tif corresponds to 2017/07/04 18:59:34

LIS_S2-SNOW-FSC_*.xml provides various metadata.

Level 3B products (L3B)
Sentinel-2 level 2B snow products have a 1-year period and a spatial resolution of 20 m. Each level 3B products is an aggregation of level 2B products over a hydrological year. The default period is 01 Sep to 31 Aug for sites in in the northern hemisphere, 01 Mar to 28-29 Feb in the southern hemisphere.

*SCD*.tif: snow cover duration in number of days i.e. the total number of snow days over the period.
*SMOD*.tif: date of snow disappearance (Snow Melt-Out Date), defined as the last date of the longest snow period. The dates are given in number of days since the first date of the synthesis.
*SOD*.tif: date of snow appearance (Snow Onset Date), defined as the first date of the longest snow period. The dates are given in number of days since the first date of the synthesis.
*NSP*.tif: number of snow periods, a snow period being a continuous period of snow cover at the daily time step (experimental)
*NOBS*.tif: number of clear observations to compute the SCD, SMOD, SOD and NSP (can be used as a quality indicator)
The filename of the product also indicates the aggregation period

start_date-end_date (date in yyymmdd format)

Sentinel-2 is an Earth observation mission developed by the European Space Agency (ESA) as part of the European Union's Copernicus program. It is designed to acquire high-resolution optical imagery for land monitoring, environmental tracking, and emergency management.

Core Characteristics

Constellation Design: Consists of two twin satellites—Sentinel-2A and Sentinel-2B—flying in the same orbit phased at 180 degrees to optimize global coverage and revisit frequency.

Revisit Rate: Provides a high revisit frequency of 5 days at the equator under cloud-free conditions, and even more frequently at mid-latitudes.

Global Coverage: Covers all Earth's land surfaces, large islands, inland waters, and territorial waters from pole to pole.

Key Capabilities & Sensors

Multi-Spectral Instrument (MSI): Captures data across 13 spectral bands ranging from visible and near-infrared (NIR) to short-wave infrared (SWIR).

Spatial Resolution: Offers varying resolutions depending on the band, including 10 meters (for natural color and NIR), 20 meters (for vegetation red-edge and SWIR), and 60 meters (for atmospheric correction).

Primary Applications

Agriculture & Forestry: Monitoring crop health, estimating yields, tracking deforestation, and managing forest resources.

Land Cover Mapping: Detecting changes in land use, urban expansion, and habitat fragmentation.

Water Resource Management: Mapping inland water bodies, monitoring coastal waters, and tracking algal blooms.

Disaster Response: Assessing natural disasters such as floods, volcanic eruptions, landslides, and wildfires to support emergency relief efforts.

Gascoin, S. (2025): Sentinel-2 snow products, https://sgascoin.github.io/INARCH

https://sgascoin.github.io/INARCH/

The data by Sentinel-2 tile are available from different sources. European catchments are already covered by Copernicus Land and can be obtained from https://doi.org/10.2909/3e2b4b7b-a460-41dd-a373-962d032795f3 . INARCH catchments outside Europe were processed by CNES over the period 01 July 2017 to 31 Aug 2023 and are available from https://hydroweb.next.theia-land.fr/ . I cropped some of these INARCH products by region of interest to simplify the data download and use (contact me if you wish to modify the region). The cropped products are available here: https://mycore.core-cloud.net/index.php/s/fRpNM2dnrUbXYeO . In the future I may include more catchments, especially in Europe if that is useful. Below are the snow cover duration (SCD) from the level 3B products.