The SLSTR uses two independent scan chains each including a separate scan mirror. While more complex than the single scan system employed by the ATSR instrument, this configuration especially increases instrument swath coverage.

  • Oblique view swath: ~ 740 km
  • Nadir view swath: ~ 1 400 km.

The nadir swath is asymmetrical with respect to the nadir point to provide identical and contemporaneous coverage with OLCI ocean/land colour measurements.

Figure 1: Outline sketch of the SENTINEL-3 SLSTR instrument viewing geometry highlighting the asymmetric nadir swath with respect to the nadir point

Following a trade-off analysis between topography and optical mission requirements, the choice of orbit for SENTINEL-3 is a sun-synchronous orbit at 814.5 km altitude (14 + 7/27 revolutions per day) with a local equatorial crossing time of 10:00 am. This satellite orbit provides a 27-day repeat.

The mean global coverage revisit time for dual view SLSTR observations is 1.9 days at the equator (one operational spacecraft) or 0.9 days (in constellation with a 180° in-plane separation between the two spacecraft) with these values increasing at higher latitudes due to orbital convergence.

Table 1: Global coverage revisit times for SLSTR optical measurements
  Constellation configuration Revisit at equator Revisit for latitude > 30° Specification
SLSTR dual view (day and night) One satellite < 1.8 days < 1.5 days < 4 days
Two satellites < 0.9 days < 0.8 days  


Figure 2: SLSTR Mean Revisit Time with Two-Satellite Configuration

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