GLOBAL SEASONAL SENTINEL-1 INTERFEROMETRIC COHERENCE AND BACKSCATTER DATA SET

Data Set Documentation

Authors:

Josef Kellndorfer, Earth Big Data LLC
Oliver Cartus, Gamma Remote Sensing AG

Date: 2021-09-08

This document describes the organization of and access to the data set Global Seasonal Interferometric Coherence and Backscatter from one year of Sentinel-1 C-band SAR data.

Availability: The data set is available via the AWS registry of open data residing in the AWS S3 Storage bucket sentinel-1-global-coherence-earthbigdata.

Table of Contents

Overview

Data Organization, Data Types and Scaling Convenvtions

Data Organization
Data Types and Scaling Conventions

Tiles

File Naming Conventions
Example listing of GeoTIFFs inside a tile
Output of gdalinfo of a sample file inside a tile

Global Mosaics

Global down-scaled mosaics at 0.01 degree resolution
Output of gdalinfo of a sample global mosaic

Global full-resolution mosaics as GDAL VRTs
Output of gdalinfo of a sample global VRT

Data Access

AWS command line tool (awscli)
HTTP URL access

License and Citation of Data Set

License
Citation

Overview

This data set is the first-of-its-kind spatial representation of multi-seasonal, global SAR repeat-pass interferometric coherence and backscatter signatures. Global coverage comprises all land masses and ice sheets from 82 degrees northern to 78 degress southern latitude. The data set is derived from high-resolution multi-temporal repeat-pass interferometric processing of about 205,000 Sentinel-1 Single-Look-Complex (SLC) data acquired in Interferometric Wide-Swath mode (Sentinel-1 IW mode) from 1-Dec-2019 to 30-Nov-2020.

The data set was developed by Earth Big Data LLC and Gamma Remote Sensing AG, under contract for NASA's Jet Propulsion Laboratory.

The data set covers seasonal (DJF/MAM/JJA/SON) metrics of:

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Data Organization

Data on the bucket are organized in tiles (full-resolution data set) and mosaics (pre-compiled global GeoTIFFs at reduced pixel spacing):

s3://sentinel-1-global-coherence-earthbigdata/data/
                                                |- tiles/
                                                |- mosaics/

Tile tiles directory also contains global and North-America gdal VRT mosaics. These were input to generate the down-scaled global mosaic geotiffs in the mosaic directory.

Tiles in the data set are labeled by the upper left coordinate of each 1x1 degree tile:

e.g.:

N48W090 covers the area of 47 to 48 degrees northern latitude, and 90 to 89 degrees western longitude (-90 to -89)
S01E012 covers the area of 2 to 1 degrees southern latitude (-2 to -1), and 12 to 13 degress eastern longitude

In each tile the following metrics (based on available polarization covering a tile) in form of a GeoTIFF file are available:

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_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_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_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

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Data Types and Scaling Conventions

Digital Numbers (DN) in the respective GeoTIFF files are scaled as follows:

Value Effect Description
0 NOT_TESTED No effect
1 TESTED Neither layover nor shadow
5 LAYOVER Pixel were slope angle is greater than look angle
16 SHADOW Pixel in area affected by shadow
21 LAYOVER IN SHADOW Layover detected in shadow areas

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Tiles

File Naming Conventions

The full resolution (3 arcsec pixel spacing) data set is organized in 1x1 degree geographic tiles. Each tile directory contains the available metrics in that tile for multi-temporal interferometric coherence, backscatter, and ancillary local incidence angle (inc) and layover/shadow (lsmap) regions.

Except for incidence angle and layover/shadow files, the naming convention is

TILEID_SEASON_POLARIZATION_METRIC.tif

with

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, or rmse

Note that for inc and lsmap files the respective relative orbit and satellite flight direction are included in the name:

Example: N42W090_092A_inc.tif

092A means Ascending (A) flightdirection, 092 means relative orbit 92.

The letter D would indicate descending flight direction.

Example listing of GeoTIFFs inside a tile:

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Output of gdalinfo of a sample file inside a tile:

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Global down-scaled mosaics at 0.01 degree resolution

We provide down-scaled global mosaics at 0.01 degree pixel spacing from spatial averaging the full-resolution mosaics.

Below is a list of all global mosaics available in the sentinel-1-global-coherence-earthbigdata/data/mosaics/ directory:

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Output of gdalinfo of a sample global mosaic

Note that overviews are embedded and data are tiled into 256x256 blocks in these cloud optimized GeoTIFFs.

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Global full-resolution mosaics as GDAL VRTs

We are providing VRT files and associated overviews for global mosaics based on the full resolution tiles. Working with these VRTs is at global scale is rather compute intensive and we recommend using our tools like Jupyter notebooks to work with regional subsets.

A listing of all available global VRTs at full resolution (located in the data/tiles/ directory) is below.

Note that VRTs with double underscores ('__') are representing VRTs of VRTs.

E.g.

Global__hh_AMP.vrt      A VRT of all Global hh_AMP.vrt files for the four seasons winter,spring,summer,fall.
Global__hh_COH.vrt      A VRT of all Global hh_COHxx.vrt files with xx in 06,12,18,24,36,48 days repeat
Global__hh_COHno06.vrt  A VRT of all Global hh_COHxx.vrt files with xx in 12,24,36,48 days repeat (No 6 day intervals)

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Output of gdalinfo of a sample global VRT

Note that overviews are external files in the global mosaic VRT Files.

Example Global__vv_COH.vrt.

The size of this VRT is 432000 x 166800 pixels by lines!

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Data Accesss

AWSCLI Tool

Using the AWSCLI tool, individual tiles can be listed and retrieved as follows:

Listing a tile:

aws s3 ls s3://sentinel-1-global-coherence-earthbigdata/data/tiles/N42W090/

Listing the global mosaics:

aws s3 ls s3://sentinel-1-global-coherence-earthbigdata/data/mosacis/

Listing the full resolution global VRTs and overview files:

aws s3 ls s3://sentinel-1-global-coherence-earthbigdata/data/tiles/Global

Retrieving a tile

aws s3 sync s3://sentinel-1-global-coherence-earthbigdata/data/tiles/N42W090/ <your-local-directory>

Downloading a file

aws s3 cp s3://sentinel-1-global-coherence-earthbigdata/data/tiles/N42W090/N42W090_fall_vv_COH12.tif <your-local-filename>

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HTML access

Each file is available via its https url link with the https prefix:

https://sentinel-1-global-coherence-earthbigdata.s3.us-west-2.amazonaws.com/ followed by data/mosaics/... or data/tiles/...

Thus, common tools like curl or wget can be used to download data via their https URL.

Tile access example https URL

https://sentinel-1-global-coherence-earthbigdata.s3.us-west-2.amazonaws.com/data/tiles/N42W090/N42W090_fall_vv_COH12.tif

Global mosaic access example https URL

https://sentinel-1-global-coherence-earthbigdata.s3.us-west-2.amazonaws.com/data/mosaics/Global_fall_vv_COH12_100ppd.tif

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License and Citation

License

The use of these data fall under the terms and conditions of the Creative Commons Attribution 4.0 International Public License

Contains modified Copernicus Sentinel data.

Citation

Any use of this data set in publications or sharing should use this citation:

"Global Seasonal Data Set of Interferometric Coherence and Backscatter from one Year of Sentinel-1 C-band SAR Data". Josef Kellndorfer, Oliver Cartus, Marco Lavalle, Christophe Magnard, Shadi Oveisgharan, Batu Osmanoglu, Paul Rosen, Urs Wegmüller. doi: In Review.