Global Seasonal Sentinel-1 Interferometric Coherence and Backscatter Dataset
Table of contents
For a full description of the data set please refer to “Global seasonal Sentinel-1 interferometric coherence and backscatter data set”. Josef Kellndorfer, Oliver Cartus, Marco Lavalle, Christophe Magnard, Pietro Mililo, Shadi Oveisgharan, Batu Osmanoglu, Paul Rosen, Urs Wegmüller. doi: 10.1038/s41597-022-01189-6 (opens in new tab)
Data Records
The dataset contains three main data records:
- 1 x 1-degree tiles. Each tile contains GeoTIFFs at 3 arcsec pixel spacing of all metrics available in the tile.
- Global Virtual Raster Tables (VRT) with external overview files of seasonal backscatter, coherence, rho, tau, and rmse including VRT stacks of seasons.
- Global mosaicked tiles as cloud optimized GeoTIFFs at 0.01-degree pixel spacing for each of the computed metrics
Naming and Organization of 1 x 1-degree tile data
The 1 x 1 degree tiles of the data set form the basic units of produced image data. All computed metrics are stored as image files in GeoTIFF format where the extent of the images covers exactly 1 degree in longitude and 1 degree in latitude with the origin of the upper left pixel at a full degree in latitude and longitude respectively. All GeoTIFFs have 3 arcseconds resolution in both dimensions and are output to a geographic reference system based on the WGS84 ellipsoid (EPSG:4326). Thus, each file in a tile has a raster dimension of 1,200 pixels by 1,200 lines. For all images, no data values are coded as the digital number zero. Global coverage encompasses a total number of 25,334 tiles.
- Tile naming convention
- Tile identifiers (TILEID) in the data set are labeled by the upper left coordinate of each 1×1 degree tile using North (N) and South (S), and East (E) and West (W) qualifiers.
- Examples
- N48W090 covers the area of 47°-48° northern latitude and 90°-89° degrees western longitude
- S01E012 covers the area of 1°-2° southern latitude and 12°-13° degrees eastern longitude
- File naming convention for backscatter, coherence, and model parameter files
- <TILEID>_<SEASON>_<POLARIZATION>_<METRIC>.tif
- TILEID = Identifier of tile referenced to upper left tile corner
- SEASON = winter, spring, summer, or fall (referring to Northern hemisphere seasons)
- POLARIZATION = vv, vh, hh, or hv
- METRIC = AMP, COHxx, rho, tau, rmse
- xx = 06, 12, 18, 24, 36, 48
- Examples
- N49E012_winter_vv_COH06.tif
- N49E012_spring_vv_COH48.tif
- N49E012_summer_vh_AMP.tif
- <TILEID>_<SEASON>_<POLARIZATION>_<METRIC>.tif
- File naming convention for incidence angle and layover/shadow files
- <TILEID>_<000><F>_<METRIC>.tif
- TILEID = Identifier of tile referenced to upper left tile corner
- 000 = Relative orbit number from 001 to 175
- F = A or D for ascending or descending flight direction
- METRIC = inc or lsmap
- Example
- N49E012_095D_inc.tif
- <TILEID>_<000><F>_<METRIC>.tif
Tiles in the dataset are labeled by the upper left coordinate of each 1×1 degree tile. Each tile contains the following metrics (based on available polarization covering a tile) as a GeoTiff file.
| Winter | |
| winter_vv_AMP | winter_hh_AMP |
| winter_vh_AMP | winter_hv_AMP |
| winter_vv_COH06 | winter_hh_COH06 |
| winter_vv_COH12 | winter_hh_COH12 |
| winter_vv_COH18 | winter_hh_COH18 |
| winter_vv_COH24 | winter_hh_COH24 |
| winter_vv_COH36 | winter_hh_COH36 |
| winter_vv_COH48 | winter_hh_COH48 |
| winter_vv_rho | winter_hh_rho |
| winter_vv_rmse | winter_hh_rmse |
| winter_vv_tau | winter_hh_tau |
| Spring | |
| spring_vv_AMP | spring_hh_AMP |
| spring_vh_AMP | spring_hv_AMP |
| spring_vv_COH06 | spring_hh_COH06 |
| spring_vv_COH12 | spring_hh_COH12 |
| spring_vv_COH18 | spring_hh_COH18 |
| spring_vv_COH24 | spring_hh_COH24 |
| spring_vv_COH36 | spring_hh_COH36 |
| spring_vv_COH48 | spring_hh_COH48 |
| spring_vv_rho | spring_hh_rho |
| spring_vv_rmse | spring_hh_rmse |
| spring_vv_tau | spring_hh_tau |
| Summer | |
| summer_vv_AMP | summer_hh_AMP |
| summer_vh_AMP | summer_hv_AMP |
| summer_vv_COH06 | summer_hh_COH06 |
| summer_vv_COH12 | summer_hh_COH12 |
| summer_vv_COH18 | summer_hh_COH18 |
| summer_vv_COH24 | summer_hh_COH24 |
| summer_vv_COH36 | summer_hh_COH36 |
| summer_vv_COH48 | summer_hh_COH48 |
| summer_vv_rho | summer_hh_rho |
| summer_vv_rmse | summer_hh_rmse |
| summer_vv_tau | summer_hh_tau |
| Fall | |
| fall_vv_AMP | fall_hh_AMP |
| fall_vh_AMP | fall_hv_AMP |
| fall_vv_COH06 | fall_hh_COH06 |
| fall_vv_COH12 | fall_hh_COH12 |
| fall_vv_COH18 | fall_hh_COH18 |
| fall_vv_COH24 | fall_hh_COH24 |
| fall_vv_COH36 | fall_hh_COH36 |
| fall_vv_COH48 | fall_hh_COH48 |
| fall_vv_rho | fall_hh_rho |
| fall_vv_rmse | fall_hh_rmse |
| fall_vv_tau | fall_hh_tau |
Data Conversion to Digital Numbers (Tile Data)
List of GeoTIFF image products and data conversion to digital numbers in a tile. No data value for all products is the digital number zero (0).
| Metric | Format | |
|---|---|---|
| Mean seasonal backscatter amplitudes γ⁰ (AMP) | Polarizations: HH, VV, HV, VH | Scaled to 16bit unsigned interger with: DN=10.0^((dB+83.0)/20.0) where: dB= 10*log10(γ⁰) |
| Median seasonal 6,12,18,24,36,48-days repeat-pass coherences (COHxx) | Polarizations: HH, VV | Coherence ρ scaled to 8bit unsigned integer with: DN=ρ*100 |
| Seasonal coherence decay-model parameters ρ∞, τ, and RMSE (rho, tau, rmse) | Polarizations: HH, VV | ρ∞, τ, RMSE scaled to 16bit unsigned integer with: DN= ρ∞/τ/RMSE*1000 |
| Local incidence angle (inc) | Per relative orbit | DN=Degrees (8bit unsigned integer) |
| Layover/shadow mask (lsmap) | Per relative orbit | 8bit unsigned integer where: 1 – No Shadow or Layover 5 – Layover 17 – Shadow 21 – Shadow in Layover |
Naming and Organization of Virtual Raster Tables
Virtual Raster Tables (VRT) are available for each seasonal mosaic of a given metric such as the 12-days coherence for the (northern hemisphere) summer or the mosaic of backscatter at VH polarization in winter. In addition, global VRTs are provided which contain all seasonal mosaics of a given metric.
For visualization purposes, external overviews were produced on these files at four overview levels reducing the full resolution global mosaic by two-dimensional down-sampling with averaging by factors of 3×3, 9×9, 27×27, and 81×81. The external overview files are identified by having a filename identical to the global mosaics with the additional postfix “.ovr” appended.
- File naming conventions for seasonal single metric VRTs
- Global_<SEASON>_<POLARIZATION>_<METRIC>.vrt
- SEASON = winter, spring, summer, or fall (referring to Northern hemisphere seasons)
- POLARIZATION = vv, vh, hh, or hv
- METRIC = AMP, COHxx, rho, tau, rmse
- xx = 06, 12, 18, 24, 36, 48
- Examples
- Global_spring_vv_COH06.vrt
- Global_winter_vh_AMP.vrt
- Global_<SEASON>_<POLARIZATION>_<METRIC>.vrt
- File naming conventions for all-season VRT stacks
- Global__<POLARIZATION>_<METRIC>.vrt
- POLARIZATION = vv, vh, hh, or hv
- METRIC = AMP, COHxx, rho, tau, rmse
- xx = 06, 12, 18, 24, 36, 48
- Examples
- Global__vv_COH06.vrt
- Global__hh_AMP.vrt
- Global__<POLARIZATION>_<METRIC>.vrt
- File naming conventions for seasonal single metric VRTs
Naming and Organization of global GeoTiff Mosaics with 0.01-degree sample spacing
From the global VRTs, downsampled cloud-optimized GeoTIFFs (COG) were generated with built-in overviews. Sample spacing in these mosaics are 0.01 degrees on both longitudinal and latitudinal directions.
- File naming convention for global 0.01-degree sample spacing GeoTiffs
- Global_<SEASON>_<POLARIZATION>_<METRIC>_100ppd.tif
- SEASON = winter, spring, summer, or fall (referring to Northern hemisphere seasons)
- POLARIZATION = vv, vh, hh, or hv
- METRIC = AMP, COHxx, rho, tau, rmse
- xx = 06, 12, 18, 24, 36, 48
- Examples
- Global_spring_vv_COH06_100ppd.tif
- Global_fall_vv_rho_100ppd.tif
- Global_<SEASON>_<POLARIZATION>_<METRIC>_100ppd.tif