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Sentinel-1 – Acquisition Maps

Sentinel-1 Data Coverage Heat Maps

Data are open-access and available through Vertex. Click on an image below to see where data products are available.

Cumulative Acquisition Maps

Two Cumulative Heat maps are updated monthly as new data is processed. One map displays the total coverage of Sentinel-1 Ground Range Detected (GRD) product data over the globe from 2014 to the last updated month in the current year, while the other map displays the total coverage of Sentinel-1 Single Look Complex (SLC) product data over the globe for the same time period. A scale of color reflects the total coverage by indicating the number of times an area has been observed.

Current Cumulative: September 30, 2020

Sentinel-1 Level 1 GRD data coverage

Sentinel-1 Level 1 SLC data coverage

Year/Month Acquisition Maps

Acquisition maps display the coverage of Sentinel-1 GRD product data over the globe in a given month. There are Acquisition maps for as early as December 2014 and maps have been recorded monthly up to present day. A scale of color indicates the number of acquisitions of an area in the specified month. 

2020

2019

2018

2017

2016

2015

2014

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Sentinel-1 – Image Quality

Users of Sentinel data may see quality issues similar to those below. Users are encouraged to submit examples of image-quality issues to uso@asf.alaska.edu.

Browse images affected by map projection

When an image granule is located above 65° latitude, the browse image can appear to be oriented and shaped differently than its outline in Vertex. The browse image is a geocoded JPEG displayed in a polar stereo map projection at latitudes above 65° in either hemisphere. The Vertex map always displays a granule in a Mercator projection. The examples show a Vertex map outline of a granule in the Arctic Ocean and an associated browse image. The browse image also is an example of stepped ends.

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Images from data close to the noise floor

Images that contain a great deal of noise have often been processed close to the noise floor (the data closest to the point where it is too noisy to be useful). The noise can look like repeating lines across an image, something like horizontal window blinds, as in the left image below. Those repeating lines are not the same as the bright spots in these images, which appear in the image below and to the right as a line of repeated bright spots or bursts. Those bright bursts are image anomalies that are not yet well understood. Also visible in these images are beam seams (see the next section).

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noisy-image-bright-bursts

Beam seams

When one image is made up of several beams, the seams can show, particularly in dark data. Beam seams are visible in many of the images on this page, including the one to the right.

Offsets between channels

Beams that seem to have noisy or missing data at one end, such as the dark blue edge at the top of the image, have been processed in one channel more than another (such as the HV or VH channels).

Stepped edges

Stepped ends, as in this image, are an artifact of the multi-beam scanning technology of TOPSAR and the way that ESA “slices” a data take into discrete, manageable units. 

Bright burst

Bright bursts are processing anomalies that are not well understood. Bright bursts are in the upper left corner of the image below at left and in the light stripe across the image below right. Also visible in the image on the left are noise (window-blind effect), beam seams, and a bit of blue on the far left that may indicate an offset between channels.

By rapidly scanning sections of all sub-swaths in the direction the satellite is traveling, TOPSAR yields more consistent image quality. Figure: De Zan, F., & Guarnieri, A. M. (2006).

Sentinel-1 – What is TOPSAR?

TOPSAR: Novel Radar Technique

Sentinel-1 uses a cutting-edge SAR technique known as Terrain Observation with Progressive Scans SAR (TOPSAR).

As this video illustrates, like standard ScanSAR, TOPSAR sends and returns radar data to and from sub-swaths that together comprise one wide swath. The difference is that TOPSAR’s radar also scans back and forth along individual sub-swaths in the azimuth direction — or the direction the satellite is moving — and it does so more rapidly than the satellite itself is traveling. Video credit: ESA.

TOPSAR enables the Extra Wide Swath (EW) and Interferometric Wide Swath (IW) modes and facilitates interferometric SAR. In these modes, bursts are synchronised from pass to pass to ensure the alignment of interferometric pairs. Interferometry uses more than one image of the same location to detect motion such as land deformation. Examples include studies of volcanoes, earthquakes, and sinkholes.

Intended to replace ScanSAR

TOPSAR mode is intended to replace the conventional ScanSAR mode, achieving the same coverage and resolution as ScanSAR, but with a nearly uniform Signal-to-Noise Ratio (SNR) and Distributed Target Ambiguity Ratio (DTAR).

Azimuth resolution is reduced compared to ScanSAR mode due to the shorter target illumination time of the burst. Using the sweeping azimuth pattern, each target is seen under the same antenna pattern, independently from its azimuth position in the burst image. By shrinking the azimuth antenna pattern, as seen by a target on the ground, scalloping effects on the image can be reduced. Bursts are synchronized from pass to pass to ensure the alignment of interferometric pairs.

For TOPSAR, the processing must handle the antenna steering rate and the DC rate due to the steering. The azimuth pre- and post-processing of the data must include deramping of the data prior to base-band DC estimation, azimuth ambiguity estimation, and GRD azimuth processing. Please see the technical note COPE-GSEG-EOPG-TN-14-0025 for details on how deramping is performed by the IPF.

By rapidly scanning sections of all sub-swaths in the direction the satellite is traveling, TOPSAR yields more consistent image quality. Figure: De Zan, F., & Guarnieri, A. M. (2006).

TOPSAR azimuth antenna sweeping causes Doppler centroid variations of approximately 5.5 kHz introducing an azimuth phase ramp (azimuth fringes) for small co-registration errors. To correct this, azimuth co-registration is required to be better than 0.001 samples (pixels) in order to obtain phase error less than 3°.

To be useful for generating interferograms, TOPSAR bursts are synchronized between repeat-pass data takes. A burst synchronization of <5 ms is required.

Content on ASF’s Sentinel web pages is adapted from the European Space Agency (ESA) Sentinel Website.

Sentinel-1 – Observation Plans

The Sentinel-1 SAR observation plan implements a baseline pre-defined mission observation scenario, making optimum use of the SAR duty cycle within the technical constraints of the overall system. This scenario aims at fulfilling, during the routine exploitation phase, the observation requirements of the Copernicus services and of ESA/EU member states. In addition, on a best effort basis and with lower priority, a secondary objective is to satisfy other SAR user communities, ensuring continuity of ERS/Envisat, considering requirements from the scientific community, as well as from international partners and cooperation activities.

High-Level Observation Plan: Highlights

Observation Scenario Maps

The maps below describe Sentinel-1 observation scenarios as of May 2017. These maps will be updated regularly. Wave mode, operated by default over open oceans, is not shown. See the ESA archive for a full list of Sentinel-1A observation scenario maps dating back to the start of the operations ramp-up phase (September 2014).

Excerpts below are from the  Sentinel High Level Operations Plan (scroll down at that link), on a repeat-cycle basis. 

European coverage:
A full two-pass (ascending and descending passes, providing at least two acquisitions for each area within 12 days) coverage in IWS mode, VV-VH polarization is provided for Europe in the extent of EEA-39 member states every 12 days  to provide data for a variety of services and applications. In addition, for European marginal seas high coverage frequency following distinct clustered requirements in IWS mode, VV-VH polarization is provided within each 12 days. An exception is for the Baltic Sea, observed partially in EWS during northern winter, on descending passes, to support sea-ice monitoring activities.

Polar environments monitoring:
Major global sea-ice zones will be observed to satisfy in particular the needs from the Copernicus Marine Environment Monitoring Service i.e.: EWS mode, HH or HH-HV polarization with some gradual increasing revisit frequency as triggered by the requirements and limited by technical constraints.

Major global ice-caps are covered at least once a year according to local winter conditions, employing IWS mode, HH polarization, and achieving at least three to four consecutive full coverage.

Worldwide coverage:
All global landmasses are regularly covered following a zonal concept in a stable one-pass IWS mode, VV-VH polarization. Zones delineation basically follows climatic-geographical considerations. Zones boundaries are extrapolated to follow administrative boundaries to provide consistent countrywide wall-to-wall coverage. During initial operations, the acquisition of distinct zones is triggered by the approach to derive a background reference dataset, among others suitable for flood monitoring during locally dry conditions which also provide the most stable radiometric conditions. The revisit frequency for all zones increased in line with the gradual mission capacity increase.

Tectonic and volcanic active areas:
Global tectonic and volcanic active areas (following an area extent definition provided by key scientists of the domain) are observed in a stable full two-pass IWS mode, VV polarization coverage with a revisit frequency of 24 days per pass (alternating ascending and descending passes, i.e. a particular area is observed every 12 days, interferometric pairs are available every 24 days). Global tectonic and volcanic active areas located within Europe are revisited within 12 days per pass in IWS mode, VV-VH polarization.

Forestry, Agriculture, Soil moisture retrieval and other specific environmental monitoring:
Key project sites all around the globe focusing on specific topics are supported from the first repeat cycles in IWS mode, with a default polarization in VV-VH, and revisit frequency individually tailored to the specific needs as far as possible.

Calibration and validation activities:
Aiming at the best achievable data quality of Sentinel-1 products, calibration and validation activities are routinely performed during the routine operations phase. These priority activities may locally and temporarily interfere with the delivery of coverage in consistent mode-polarization combination. Major regions affected by these activities are Northern Alpine Lowlands (Germany, Austria and Switzerland) and the narrow surroundings of Sao Paulo (Brazil), Houston and Chicago (USA). Limiting the consistency of static mode–polarization coverage and causing small observation gaps due to instrument switches, these activities bring the opportunity to explore the variety of the Sentinel-1 image modes to data users of the affected areas.

Content on ASF’s Sentinel web pages is adapted from the European Space Agency (ESA) Sentinel website.

Sentinel-1 – How to Cite

Citing Sentinel Data

Cite datasets in publications such as journal papers, articles, presentations, posters, and websites. For more information, see Terms and Conditions. Please send copies of, or links to, published works citing data, imagery, or tools accessed through ASF to uso@asf.alaska.edu with “New Publication” on subject line.

Type Format Example
Data, primary Copernicus Sentinel data [year of data acquisition]. Retrieved from ASF DAAC [day month year of data access], processed by ESA. Copernicus Sentinel data [year of data acquisition]. Retrieved from ASF DAAC [day month year of data access], processed by ESA.
Data, modified [creator credit, year created], contains modified Copernicus Sentinel data [year of data acquisition], processed by ESA. ASF DAAC 2015, contains modified Copernicus Sentinel data 2015, processed by ESA.

Citing Sentinel Imagery

Include appropriate credit with each image shown in publications such as journal papers, articles, presentations, posters, and websites.

Type Format Example
Data, primary Copernicus Sentinel data [year of data acquisition], processed by ESA. Copernicus Sentinel data 2015, processed by ESA.
Data, modified [creator credit, year created], contains modified Copernicus Sentinel data [year of data acquisition], processed by ESA. ASF DAAC 2015, contains modified Copernicus Sentinel data 2015, processed by ESA.

Sentinel-1 – Terms and Conditions

European Space Agency Legal Notice on the Use of Copernicus Sentinel Data and Service Information

The access and use of Copernicus Sentinel Data and Service Information is regulated under EU law.1 In particular, the law provides that users shall have a free, full and open access to Copernicus Sentinel Data2 and Service Information without any express or implied warranty, including as regards quality and suitability for any purpose.3

EU law grants free access to Copernicus Sentinel Data and Service Information for the purpose of the following use in so far as it is lawful4 :

     (a) reproduction;

     (b) distribution;

     (c) communication to the public;

     (d) adaptation, modification and combination with other data and information;

     (e) any combination of points (a) to (d).

EU law allows for specific limitations of access and use in the rare cases of security concerns, protection of third party rights or risk of service disruption.

By using Sentinel Data or Service Information the user acknowledges that these conditions are applicable to him/her and that the user renounces to any claims for damages against the European Union and the providers of the said Data and Information. The scope of this waiver encompasses any dispute, including contracts and torts claims, that might be filed in court, in arbitration or in any other form of dispute settlement.

Where the user communicates to the public or distributes Copernicus Sentinel Data and Service Information, he/she shall inform the recipients of the source of that Data and Information by using the following notice5 :

  1. ‘Copernicus Sentinel data [Year]’ for Sentinel data; and/or
  2. ‘Copernicus Service information [Year]’ for Copernicus Service Information.

Where the Copernicus Sentinel Data and Service Information have been adapted or modified, the user shall provide the following notice:

  1. ‘Contains modified Copernicus Sentinel data [Year]’ for Sentinel data; and/or
  2. ‘Contains modified Copernicus Service information [Year]’ for Copernicus Service Information.

The users’ rights on their personal data are protected under European law6. Such data will only be used by the European Commission and the providers of the said Data and Information for providing services to the user and for statistical as well as evaluation purposes.

1 Regulation (EU) No 377/2014 and Commission Delegated Regulation (EU) No 1159/2013.
2 In agreement with the Copernicus Sentinel Data Policy, ESA/PB-EO(2013)30, rev. 1. 
3 See in particular Art. 3 and 9 of Regulation 1159/2013. 
4 See in particular Art. 7 of Regulation 1159/2013. 
5 See in particular Art. 8 of Regulation 1159/2013. 
6 Directive 95/46/EC of the European Parliament and of the Council of 24 October 1995 on the protection of individuals with regard to the processing of personal data and on the free movement of such data; Regulation (EC) No 45/2001 (EC) No 45/2001 of the European Parliament and of the Council of 18 December 2000 on the protection of individuals with regard to the processing of personal data by the Community institutions and bodies and on the free movement of such data.

Sentinel-1 – Documents and Tools

Resources include product specification documents, dataset citation information for scientists using Sentinel-1 synthetic aperture radar (SAR) data, and references for relevant scientific literature. …

Sentinel-1 – Instrument

Launches:
  • Sentinel-1B: Soyuz rocket, launched 25 April 2016, from Kourou, French Guiana
  • Sentinel-1A: Soyuz rocket, launched 3 April 2014, from Kourou, French Guiana

Orbit: Polar, sun-synchronous at an altitude of 693 km

Revisit time: Six days with two-satellite constellation of Sentinel-1A and 1B. Before 1B launched, revisit time for Sentinel-1A alone was 12 days.

Instrument: C-band synthetic aperture radar (SAR) at 5.405 GHz

Operational Modes
  • Interferometric wide-swath (IW) at 250 km and 5×20 m resolution, using TOPSAR
  • Wave (WV) images of 20×20 km and 5×5 m resolution (at 100 km intervals)
  • Stripmap (SM) at 80 km swath and 5×5 m resolution
  • Extra wide swath (EW) of 400 km and 20×40 m resolution, using TOPSAR
Polarization
  • Supports operation in single polarization (HH or VV) and dual polarization (HH+HV or VV+VH)
  • Polarization implemented through one transmit chain (switchable to H or V) and two parallel receive chains for H and V polarization
  • SM, IW and EW are available in single (HH or VV) or dual polarization (HH+HV or VV+VH)
  • WV is single polarization only (HH or VV)

Receiving stations: SAR data: Svalbard, Norway; Matera, Italy; Maspalomas, Spain; and via laser link through EDRS (European Data Relay System)

Telemetry, tracking and command: via Kiruna, Sweden

Main applications: Monitoring sea ice, oil spills, marine winds and waves, land-use change, land deformation, and to respond to emergencies such as floods and earthquakes

Mission: Developed, operated, and managed by various ESA establishments

Life: Minimum of seven years

Satellites: 2.8 m long, 2.5 m wide, 4 m high with 2×10 m-long solar arrays and a 12 m-long radar antenna

Mass: 2300 kg (including 130 kg fuel)

Funding: ESA Member States and the European Union Prime contractors: Thales Alenia Space, Italy, for the satellite; Airbus Defence and Space, Germany, for the SAR instrument

Content on ASF’s Sentinel web pages is adapted from the European Space Agency (ESA) Sentinel website.

This time-lapse video shows Sentinel-1A being prepared for launch and its liftoff on 3 April 2014 from Europe’s Spaceport in French Guiana. Credit: ESA – S. Corvaja,  M. Pedoussaut, 2014.

Sentinel-1B launches on 25 April 2016 from Europe’s Spaceport in French Guiana. © ESA/CNES/Arianespace.