Using Theia layers

Theia's Monthly Mosaic of France from Sentinel2

Theia produces atmospheric-corrected surface reflectance images over about 5 million km2 using the MAJA software.

These single-date products (level 2A) are then processed monthly with the WASP software to produce 45-day cloud-free (so-called level 3A) syntheses.

These two products 2A (single date) and 3A (monthly) are available in our download catalog and retain the basic characteristics of Sentinel-2 images, i.e. a geographical coverage of 100x100km and the 13 spectral bands.

On the contrary, the map layers diffused here are the result of an assembly of the 100x100kms products to make a continuous product (called mosaic), diffused in WM(T)S layers and limited to 3 bands for on-screen display.

Three by-products are thus diffused:

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About Land Use Land Cover Layer

The availability Sentinel-2 imagery with its unique characteristics (290 km swath, 10 to 60 m spatial resolution, 5-day revisit cycle with 2 satellites, 13 spectral bands) enables the implementation of land cover map production systems for the delivery of accurate information with the appropriate frequency.

The French Theia Land Data Centre has set up a Land Cover Scientific Expertise Centre in order to implement an fully operational automatic land cover map production system (iota2) using mostly Sentinel-2 image time series. The LULC product is updated once a year and contains ~17 thematic classes mapped at 10 m resolution.

Glacier elevation change rate between 2000 and 2019

Surface elevation change rates of all glaciers and their vicinity (10 km buffer) between 2000 and 2019, from the study of [Hugonnet et al. (2021)](DOI soon) which is the reference to cite when using or plotting these data.

The products can be downloaded by tiles of 1° x1° and by period by accessing the links displayed when passing the cursor on a given tile. Bulk downloading is available at the links at the bottom of this page.

Elevation changes are distributed at a horizontal resolution of 100 m x 100 m and for the 5-year periods of 2000–2004, 2005–2009, 2010–2014 and 2015–2019, the 10-year periods of 2000–2009 and 2010–2019 and the full 20-year period of 2000–2019.
Periods refer to inclusive calendar years of 1st January to 1st of January (e.g., 2000–2004 is January 1, 2000 to January 1, 2005).

Elevation changes are provided as annual rates (in meters per year), allowing comparison of changes between different subperiods. The following colormap is used in all instances :

The glaciers mapped are based on the Randolph Glacier Inventory 6.0.

The surface elevation change estimation derives from fitting Gaussian Process regression to time series of elevation observations from multiple Digital Elevation Models (DEMs).
DEMs are primarily generated and corrected from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) stereo imagery [ASTL1A].

DEMs from the archives of ArcticDEM and of the Reference Elevation Model of Antarctica, derived from WorldView and GeoEye imagery, are also used in the polar regions.

More scientific information is available in [the article](DOI soon).

Bulk downloading of all data products is available as a dataset of Observatoire Midi-Pyrénées’s Sedoo.

Code and guides to manipulate the dataset at different scales are available on a dedicated GitHub repository.

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Theia cartographic layers

This application has been put in place internally (CNES/CESBIO/IRD/INRAE) :