| Import Sentinel-1 | |
Operational: S1A 2014-04-03 to present, S1B 2016-04-25 to present
Frequency Band: C-band
Acquisition Modes: Interferometric Wideswath (IW), Extra Wideswath (EW), Stripmap (SM) and Wave (WV)
Product Types: Single Look Complex (SLC), Ground Range Detected (GRD), Ocean (OCN)
SENTINEL data products are distributed using a SENTINEL-specific variation of the Standard Archive Format for Europe (SAFE) format specification. The SAFE format has been designed to act as a common format for archiving and conveying data within ESA Earth Observation archiving facilities.
The SENTINEL-SAFE format wraps a folder containing image data in a binary data format and product metadata in XML. This flexibility allows the format to be scalable enough to represent all levels of SENTINEL products.
A SENTINEL product refers to a directory folder that contains a collection of information. It includes:
The manifest file is an XML file containing the mandatory product metadata common to all SENTINEL-1 products.
Annotated data sets contain metadata describing the properties and characteristics of the measurement data or how they were generated. For each band of data there is a product annotation data set that contains metadata describing the main characteristics corresponding to that band such as the state of the platform during acquisition, image properties, polarisation, Doppler information, swath merging and geographic location. Calibration annotations contain calibration information and the beta nought, sigma nought, gamma and digital number look-up tables that can be used for absolute product calibration. Noise data annotations contain the estimated thermal noise look-up tables. Annotated data sets are provided in XML format. Level-2 products do not contain annotation data sets as all product metadata is contained within the netCDF product file.
In the preview folder, quicklook data sets are power detected, averaged and decimated to produce a lower resolution version of the image. Single polarisation products are represented with a greyscale image. Dual polarisation products are represented by a single composite colour image in RGB with the red channel (R) representing the first polarisation, the green channel (G) represents the second polarisation and the blue channel (B) represents an average of the absolute values of the two polarisations. Level-2 OCN products do not contain quicklooks.
Representation data sets found in the support folder contain information about the format or syntax of the measurement and annotated data sets and can be used to validate and exploit these data. Representation data sets are provided as XML schemas.
Measurement data sets contain the binary information of the actual acquired or processed data. For Level-0 this is the instrument data, for Level-1 it is the processed images and for Level-2 it is the derived data. There is one measurement data set per polarisation and per swath. TOPSAR SLC products contain one complex measurement dataset in GeoTIFF format per swath per polarisation. Level-1 GRD products contain one detected measurement dataset in GeoTIFF format per polarisation.
Measurement data sets are provided in GeoTIFF format for Level-1 products and netCDF format for Level-2 products. The Level-2 OCN products in netCDF format include both the annotation and measurement datasets described as netCDF attributes, dimensions and variables in one self-describing, self-contained file.
Level 1 SLC: L1 Single Look Complex (SLC) products consists of focused SAR data geo-referenced using orbit and attitude data from the satellite and provided in zero-Doppler slant-range geometry. The products include the full TX signal bandwidth and uses complex samples preserving the phase information. Stripmap SLCs contain one image per swath and polarization band. SM contains 1 image per polarization band. IW, having 3 swaths, has 3 images in single pol and 6 images for dual pol. EW, having 5 swaths, has 5 image for single pol and 10 image for dual pol. Each sub-swath consists of a series of bursts. Each burst has been processed as a separate SLC image.
Level 1 GRD: L1 Ground Range Detected (GRD) products consist of focused SAR data that has been projected to ground range using an Earth ellipsoid model, detected and multilooked. Phase information is lost. GRD products can be in one of three resolutions Full Resolution (FR), High Resolution (HR), or Medium Resolution (MR). L1 GRD products come in MR and HR for IW and EW modes, MR for WV mode and MR, HR and FR or SM mode.
Level 2 OCN: The L2 Ocean products may include Ocean WInd field (OWI), Ocean SWell spectra (OSW) and surface Radial VeLocity (RVL) information derived from the SAR data. The OWI is a ground range gridded estimate of the surface wind speed and direction at 10m above the surface derived from the L1 GRD images of SM, IW or EW modes. The OSW is a two-dimensional ocean surface swell spectra and also includes an estimate of the wind speed and direction per swell spectrum. The OSW is generated from SM and WV modes only. For SM, there are multiple spectras derived from the L1 SLC image. For WV, there is one spectra per vignette. The RVL is a ground range gridded difference between the measured L2 Doppler grid and the L1 calculated geometrical Doppler.
Polarizations: Dual Pol VV+VH or HH+HV
Primary metadata file: manifest.safe
Opening products: Products can be opened by selecting the manifest.safe file. Opening zipped products (*.zip) directly is also supported.
Further Information:
https://sentinel.esa.int/web/sentinel/user-guides/sentinel-1-sar
https://directory.eoportal.org/web/eoportal/satellite-missions/c-missions/copernicus-sentinel-1