The Sentinel-1 Data Processor and Operational Products
Miranda, Nuno1; Rosich, Betlem1; Putignano, Cosimo2

The European Space Agency (ESA) is developing the Sentinel-1 (S-1) mission in the frame of the Global Monitoring for Environment and Security programme (GMES) [ 1]. Sentinel-1 is a polar orbiting satellite system carrying on-board a Synthetic Aperture Radar (SAR) working at C-band. Sentinel-1 aims at ensuring the continuity of radar observation and the sustainability the operational applications. The Sentinel-1 Payload Data Ground Segment (PDGS) is in charge of the acquisition, production, dissemination and archiving of the Sentinel-1 products. The processing function is fulfilled by the Sentinel-1 Instrument Processing Facility (IPF) that is responsible for the full product family generation. This paper provides an overview the Sentinel-1 operational products including main product characteristics and gives an insight of the IPF architecture, its functionalities and processing algorithms. The Level 0 products although being available to the users are not discussed in this paper. The Sentinel-1 operational product family has been thought such that it ensures continuity with the ERS and ASAR product family and extends it to make available the latest achievement in terms of algorithm development. The product family tree (Fig 1) is composed by Level 1 (L1) and Level 2 (L2) products. The L1 products are the classical Single Look Complex (SLC) and Ground Range Detected (GRD) products. The SLC products strongly inherit from ERS and ASAR and have a lot in common. However the specific case of the TOPS (Terrain Observation with Progressive Scan) [ 2] SLC products will be particularly addressed. TOPS is a new acquisition mode, that will used for the first time as main operational mode for Sentinel-1. The double steering of the antenna in azimuth and elevation (combination of SCANSAR and inverse SPOT) makes the TOPS SLC products pretty different from the well-known STRIPMAP SLC. The L2 product family has been extended with respect to the ERS and ASAR on many respects. While for ASAR only swell spectra were available, it has now been completed with wind fields and surface radial velocities that is a gateway to ocean surface currents. These geophysical variables are packed in a unique product called the OCeaN (OCN) product of particular interest for climate and environment applications. In terms of format, the Sentinel-1 product family is following the most recent conventions adopted by different space agencies. In particular for level 1 products, the format is based on well known technologies and user-oriented format like XML and geotif. The L2 products are following the Netcdf climate and forecast conventions [ 3] to foster the comparison, validation and finally usage with other data sources. Finally, this paper presents the Sentinel-1 IPF. It discusses its architecture, functionality and the algorithm implemented and the performance results obtained. Fig 1. Sentinel-1 product family tree 2. REFERENCES [ 1] E. Attema, “GMES Sentinel-1 Mission Requirement Document”, ESA document, ES-RS-ESA-SY-0007, issue/rev 1.4, 11/07/2005 [ 2] De Zan, F., & Guarnieri, A. M. (2006). TOPSAR: Terrain Observation by Progressive Scans. Geoscience and Remote Sensing, IEEE Transactions on, 44(9), 2352–2360. doi:10.1109/TGRS.2006.873853 [ 3] B. Eaton & al., “NetCDF Climate and Forecast (CF) Metadata Conventions”, Version 1.6, 5 December, 2011