Sentinel-1 Observation Scenario

Sentinel-1 - Observation Scenario

Sentinel-1 SAR observation scenario 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.

The elaboration of a pre-defined observation plan necessitates solving, a priori, the potential conflict among users (e.g. different SAR operation modes or polarisation schemes required over same geographical area).

During the ramp-up exploitation phase, the Sentinel-1 observation plan gradually evolves in line with the increasing operational capacity. Accordingly, the observations and volume of data available to Sentinel-1 operational users gradually increase during this period.

Within the predefined observation plan, the Sentinel-1 mission ensures observations fulfilling the following two main categories of services:

  • Monitoring services related to oceans, seas and sea-ice. These services require quasi real-time or near real-time data, typically in less than 3 hours, and in some cases in less than 10 minutes. Quasi real-time services or services requiring data within 1 hour from sensing require reception by local stations. Most of these monitoring types of services require systematic or very frequent (e.g. daily) observations.
  • Services/applications over land. These services or applications cover a wide range of different thematic domains. They generally do not require data in quasi real-time and few of them require data within 3 hours (near real-time) from sensing. Related data are mostly recorded on-board and downloaded to the core ground station network. Products not required in near real-time are available within 24 hours from sensing, in practice the availability of these products is reduced to few hours from sensing.

The high level Sentinel-1 observation strategy during full operations capacity is based on:

  • optimum use of SAR duty cycle for high modes (25 min/orbit during eclipse season from early May to early August, 30 min outside eclipse season), taking into account the various constraints (e.g. limitation in the number of X-band RF switches, mode transition times, maximum downlink time per orbit and maximum consecutive downlink time)
  • optimum use of single and dual polarisation acquisitions, in line with the available downlink capacity (in practice most observations are now performed in dual polarisation)
  • Wave Mode (WV) continuously operated over open oceans, with lower priority versus the high rate modes
  • Interferometric Wide swath (IW) and Extra Wide swath (EW) modes operated over pre-defined geographical areas:
    • over land and coastal areas: pre-defined mode is IW
    • over seas and polar areas, and ocean relevant areas, pre-defined mode is either IW or EW.

In exceptional cases only, emergency observation requests may alter the pre-defined observation scenario, potentially requiring the use of the Stripmap (SM) mode.

Over land, the same SAR polarisation scheme is systematically used over a given area, to guarantee time series of data in the same conditions for routine operational services and to allow frequent InSAR. Depending on the area, the selection is either vertical or horizontal, the choice being made according to the main application behind.

As a general principle, the polarisation scheme uses the following logic:

  • HH-HV or HH polarization for the monitoring of polar environments, sea-ice zones
  • VV-VH or VV polarization for all other observation zones (with an exception for the Baltic Sea observed partially in HH-HV with Sentinel-1B during northern winter)

Please see the Sentinel High Level Operations Plan for specific details about the high level operations concept and strategy of the Sentinel missions.

See the archive for the full list of Sentinel-1 observation scenario maps dating back to the start of the Sentinel-1A operations ramp up phase (September 2014).

Detailed information on the planned Sentinel-1 observations in terms of Sentinel-1 acquisitions (SAR mode, date, start-stop times, polarization, etc) are provided with KML files available here.

The end of mission of the Sentinel-1B satellite has been declared in July 2022.

An overview of the current Sentinel-1A observation plan in terms SAR mode, polarisation, observation geometry, revisit and coverage frequency, starting as of September 2022, is shown on the two maps below.

The Wave mode, continuously operated by default over open oceans, is not shown on these maps.

The detailed Sentinel-1A observation plan is available here.

For information, the two maps below show an overview of the Sentinel-1 observation plan based on the observations of a 2-satellite constellation.

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