Time Tags, Locations and Surface Types – Sentinel-3 Altimetry Technical Guide – Sentinel Online
- Table 1: The distance to the coast is computed using the theoretical distance to the shore table of the SENTINEL-3 mission.
- Table 2: The orbit parameters (latitude and longitude) are computed, interpolating them at the time of the measurement.
- Table 3: The time-tags of the measurements are the UTC seconds elapsed since 1 January 2000.
- Table 4: The altitude rate of the altimeter measurement is used to determine the closest grid point to the shore table.
- Table 5: The altitude is computed, interpolating it at the time of measurement.
- Table 6: The surface type can be set to open ocean or semi-enclosed seas, enclosed seas or lakes, continental ice or land.
PARAMETER |
Distance to the coast |
NETCDF NAME |
dist_coast_[x1]_[x2] where: |
DESCRIPTION |
Distance to the coast at time time_[x1]_[x2]. The distance to the coast is computed using the theoretical distance to the shore table of the SENTINEL-3 mission. The altitude rate of the altimeter measurement is used to determine the closes grid point to the shore table. |
UNITS |
m |
DATA SET AVAILABILITY |
Reduced: 1 Hz only |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: GEN_ENV_DIS_01 |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
None |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
Table 1. Distance to the coast
PARAMETER |
Latitude and Longitude |
NETCDF NAME |
lat_[x1]_[x2] |
DESCRIPTION |
Latitude position at time time_[x1]_[x2]. |
UNITS |
10-6 degrees |
DATA SET AVAILABILITY |
Reduced: 1 Hz only |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: Orbit CFI algorithm |
ADDITIONAL INFORMATION |
Positive latitude is North latitude, negative latitude is South latitude. East longitude relative to the Greenwich meridian. |
PARAMETERS RELATED |
None |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
Table 2. Latitude and Longitude
PARAMETER |
Time-Tag |
NETCDF NAME |
time_[x1]_[x2] where: |
DESCRIPTION |
Time of the occurrence of the measurement. UTC time elapsed since January 1st 2000. This time has been: |
UNITS |
seconds |
DATA SET AVAILABILITY |
seconds |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: ALT_MAN_TIM_01 algorithm |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
1.UTC days and seconds in the day elapsed since January 1st 2000 (UTC_day_[x1]_[x2] and UTC_sec_[x1]_[x2]) |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
Table 3. Time tags
PARAMETER |
Orbital Altitude Rate |
NETCDF NAME |
orb_alt_rate_[x1]_[x2] |
DESCRIPTION |
The satellite altitude rate is the height rate of the satellite at time time_[x1]_[x2]. |
UNITS |
10-2 m/s |
DATA SET AVAILABILITY |
Reduced: none |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: Orbit CFI algorithm |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
None |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
Table 4. Orbit
PARAMETER |
Orbit altitude |
NETCDF NAME |
alt_[x1]_[x2] |
DESCRIPTION |
The satellite altitude is the height of the satellite above the reference ellipsoid at time time_[x1]_[x2]. This algorithm uses an ESA library called CFI Software Explorer Orbit that computes altitude interpolating them from the satellite orbit state vector positions file at the precise time of the input measurement. |
UNITS |
10-4 m. An offset of 700 000 m to be added to the value read from the netCDF file. |
DATA SET AVAILABILITY |
Reduced: 1 Hz only |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands:Orbit CFI algorithm |
ADDITIONAL INFORMATION |
For further information about orbit CFI, CFI Website |
PARAMETERS RELATED |
None |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
Table 5. Altitude
PARAMETER |
Surface types |
NETCDF NAME |
surf_type_[x1]_[x2] where: |
DESCRIPTION |
Surface type at time time_[x1]_[x2]. Surface type is computed using the land/sea mask of the SENTINEL-3 mission. The latitude and longitude of the altimeter measurement are used to determine the nearest grid point in the land/sea mask file. The surface type is set to the surface type reported for this nearest grid point. |
UNITS |
The possible surface types are: |
DATA SET AVAILABILITY |
Reduced: 1 Hz only |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: SRAL Level-1B product |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
Radiometer-derived surface type (rad_surf_type[x1]_[x2]): The algorithm that computes the radiometer-derived surface type is RAD_MAN_INT_03. This algorithm averages/interpolates the radiometer data at 7 Hz to the 1 Hz altimeter time tags. |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
Table 6. Surface type