Minimize Definitions

Auxiliary Data

Describes all auxiliary information that will be used by the Payload Data Ground Segment (PDGS) for the processing of MSI data. The auxiliary data required in MultiSpectral Instrument (MSI) data generation are:

  • Ground Image Processing Parameters (GIPP)
  • Digital Elevation Model (DEM) (see below)
  • Global Reference Image (GRI)
  • European Centre for Medium-Range Weather Forecasts (ECMWF): ozone, surface pressure and water vapour data required for Level-1C processing
  • International Earth Rotation & Reference Systems service (IERS) data
  • Precise Orbit Determination (POD) data.

Datatake

The continuous acquisition of an image from one SENTINEL-2 satellite in a given MSI imaging mode is called a "datatake". The maximum length of an imaging datatake is 15,000 km (continuous observation from northern Russia to southern Africa).

Datastrip

Within a given datatake, a portion of image downlinked during a pass to a given station is termed a "datastrip". If a particular orbit is acquired by more than one station, a datatake is composed of one or more datastrips. It is expected that the maximum length of a datastrip downlinked to a ground station is approximately 5,000 km.

DEM
Orthorectification in the L1C uses the 90m DEM (PlanetDEM 90). The PlanetDEM 90 is reprocessed from 90 metre SRTM (Shuttle Radar Topography Mission) source data. For PlanetDEM 90 data, the SRTM input data (v4.1) has been improved over specific mountain areas, and corrected over deserts and parts of the USA, using GDEM and NED.

Granules and Tiles

A granule is the minimum indivisible partition of a product (containing all possible spectral bands).

  • For Level-0, Level-1A and Level-1B, granules are sub-images of a detector with a given number of lines along track. A granule covers approximately 25 km across-track and 23 km along-track.
  • For Level-1C, the granules, also called tiles, are 100 km2 ortho-images in UTM/WGS84 projection.

Quality Indicator

A medium that accompanies the data and can be used to obtain information necessary to determine the suitability of a product for a certain use or application. Examples of quality indicators are: defective pixels mask, cloud masks, on-line quality control reports, etc.

Timeliness

There are three categories of timeliness defined for SENTINEL-2 operation:

  • Nominal, corresponding to the on-line availability of product between 3 and 24 hours after sensing
  • Near Real-Time (NRT), corresponding to the on-line availability of product between 100 minutes and 3 hours after data sensing
  • Real-Time (RT), corresponding to the on-line availability of product no later than 100 minutes after data sensing

True Colour Images (TCI)

Following the introduction of the Compact Naming Convention on the 6th of December 2016 (see the Sentinel-2 User Guide Product Naming Convention page for details), a TCI (True Colour Image) in JPEG2000 format is included within the Tile folder of Level-1C products in this format(1). The TCI is an RGB image built from the B02 (Blue), B03 (Green), and B04 (Red) Bands. The reflectances are coded between 1 and 255, 0 being reserved for 'No Data'. The saturation level of 255 digital counts correspond to a level of 2000 for the individual bands (i.e. reflectance of 0.2).

(1) Products acquired before the 6th of December 2016, and products reprocessed within the PDGS  - including those Reprocessed after the 6th of December - still use the old format Naming Convention.