Understand the Data
Model overview
We currently produce two families of cloud-free Sentinel-2 images:
- Stratus: Our 10-band, harmonized, bottom-of-atmosphere (BOA) product (Sen2Cor-corrected L2A). This is our long-standing default.
- Nimbus: Our 100% Sentinel-2 compatible product. It includes the same 10 bands as Stratus and the remaining Sentinel-2 MSI bands:
- Nimbus (L2A/BOA): Full S2 band set except B10 (Cirrus), which is not present in L2A.
- Nimbus (L1C/TOA): Full S2 band set including B10 (Cirrus).
Tip: Regardless of the native Sentinel-2 resolution per band, ClearSKY composites are delivered at the output resolution you request in the Processing API (e.g., 10 m).
Band coverage by model
| Band ID | Common name | Stratus L2A | Nimbus L2A/BOA | Nimbus L1C/TOA |
|---|---|---|---|---|
| B1 | Coastal aerosol | ✗ | ✓ | ✓ |
| B2 | Blue | ✓ | ✓ | ✓ |
| B3 | Green | ✓ | ✓ | ✓ |
| B4 | Red | ✓ | ✓ | ✓ |
| B5 | Red-edge 1 | ✓ | ✓ | ✓ |
| B6 | Red-edge 2 | ✓ | ✓ | ✓ |
| B7 | Red-edge 3 | ✓ | ✓ | ✓ |
| B8 | Near infrared (NIR) | ✓ | ✓ | ✓ |
| B8A | Narrow NIR | ✓ | ✓ | ✓ |
| B9 | Water vapour | ✗ | ✓ | ✓ |
| B10 | Cirrus | ✗ | ✗ | ✓ |
| B11 | SWIR 1 | ✓ | ✓ | ✓ |
| B12 | SWIR 2 | ✓ | ✓ | ✓ |
Compatibility: Nimbus is the first ClearSKY model family that exposes the full Sentinel-2 band set, making it truly Sentinel-2 compatible. Use band IDs (e.g.,
B2,B8A) in yourbandnameswhen downloading.
Stratus
The imagery is available as multi-spectral GeoTIFFs with the following Stratus spectral bands (output resolution is what you request; table shows typical 10 m usage).
| Band Name | Band ID | Resolution (m) | Wavelength (nm) | Band Order |
|---|---|---|---|---|
| Blue | B2 | 10 | 492 ± 33 | 1 |
| Green | B3 | 10 | 559 ± 18 | 2 |
| Red | B4 | 10 | 664 ± 15 | 3 |
| Red-Edge 1 | B5 | 10 | 704 ± 8 | 4 |
| Red-Edge 2 | B6 | 10 | 740 ± 7 | 5 |
| Red-Edge 3 | B7 | 10 | 782 ± 10 | 6 |
| Near Infrared | B8 | 10 | 732 ± 53 | 7 |
| Narrow Near Infrared | B8A | 10 | 864 ± 11 | 8 |
| Shortwave Infrared 1 | B11 | 10 | 1613 ± 47 | 9 |
| Shortwave Infrared 2 | B12 | 10 | 2200 ± 92 | 10 |
Note on order: Rely on band IDs, not on column order. When calling the Processing API, pass
bandnamesexplicitly (e.g.,"rgb"or"B8,B4,B3").
Nimbus
Nimbus adds the remaining Sentinel-2 MSI bands. These bands are commonly native at 60 m in Sentinel-2, but your ClearSKY output will match the requested output resolution (e.g., 10 m) in the Processing API.
| Band Name | Band ID | Resolution (m) | Wavelength (nm) | Availability |
|---|---|---|---|---|
| Coastal aerosol | B1 | 10 | 443 ± 20 | Nimbus L2A & L1C |
| Water vapour | B9 | 10 | 945 ± 20 | Nimbus L2A & L1C |
| Cirrus | B10 | 10 | 1375 ± 15 | Nimbus L1C only |
Data types & scaling
- Data type:
uint8orint16 - NODATA:
-32768(forint16) - Reflectance scaling:
- Spectral bands ÷ 10000 to convert to reflectance.
- Indices ÷ 32767.
- Precomputed indices returned by the API are in [-1, 1]. For larger ranges, download bands and compute the index locally.
Metadata tags (GeoTIFF)
GeoTIFFs retrieved through the Processing API include these tags:
- IMAGE_DATE — date of the image, formatted as
yyyymmdd. - MODEL_VERSION — version of the model used for prediction.
- IMAGE_VERSION — increments when a tile is regenerated.
- CONSTELLATIONS — satellite constellations used (e.g.,
Sentinel1orSentinel1,Sentinel2,Landsat89).
When a request overlaps multiple tiles, IMAGE_VERSION lists one value per intersecting tile, comma-separated, in our internal order (not numerical sort). Example: 13,15,13,13. A change to 13,15,13,15 indicates the last tile was updated to version 15.
Choosing bands in the API
- Use the
bandnamesparameter (e.g.,"rgb","all", or specific bands like"B8,B4,B3"). - For indices (e.g., NDVI), you can use index expressions like
"[B8_B4]"or compute locally from downloaded bands. - Prefer UTM EPSG projections (e.g., 326xx/327xx) for best quality in resampling and reprojection.