Minimize Time Tags, Locations and Surface Type
  • 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:
[x1]: 1 Hz or 20 Hz data rates
[x2]: Ku-band or C-band

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
Standard: 20 Hz Ku-band only
Enhanced: 20 Hz Ku-band only

OPERATING MODE AVAILABILITY

LRM and SAR

DATA ORIGIN

1 Hz Ku/C-bands: GEN_ENV_DIS_01
20 Hz Ku-band: GEN_ENV_DIS_01
20 Hz C-band: none

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]
lon_[x1]_[x2]
[x1]: 1 Hz or 20 Hz data rates
[x2]: Ku-band or C-band

DESCRIPTION

Latitude position at time time_[x1]_[x2].
Longitude position at time time_[x1]_[x2].
This algorithm uses an ESA library called CFI Software Explorer Orbit that computes both latitude and longitude, interpolating them from the satellite orbit state vector positions file at the precise time of the input measurement.

UNITS

10-6 degrees

DATA SET AVAILABILITY

Reduced: 1 Hz only
Standard: all
Enhanced: all

OPERATING MODE AVAILABILITY

LRM and SAR

DATA ORIGIN

1 Hz Ku/C-bands: Orbit CFI algorithm
20 Hz Ku-band: Orbit CFI algorithm
20 Hz C-band: 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:
[x1]: 1 Hz or 20 Hz data rates
[x2]: Ku-band or C-band

DESCRIPTION

Time of the occurrence of the measurement. UTC time elapsed since January 1st 2000. This time has been:
*converted from on-board time counters
*referenced to the overflown surface
*referenced to the middle of the tracking cycle

UNITS

seconds

DATA SET AVAILABILITY

seconds

OPERATING MODE AVAILABILITY

LRM and SAR

DATA ORIGIN

1 Hz Ku/C-bands: ALT_MAN_TIM_01 algorithm
20 Hz Ku-band: SRAL Level-1B product
20 Hz C-band: SRAL Level-1B product

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])
2.Time-tag of the 1 Hz measurement (UTC_time_1hz_[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]
[x1]: 1 Hz or 20 Hz data rates
[x2]: Ku-band or C-band

DESCRIPTION

The satellite altitude rate is the height rate of the satellite at time time_[x1]_[x2].
The reference surface for the orbital altitude rate is the combined mean sea surface/geoid surface.
The orbital altitude rate is used to compute the Doppler correction on the altimeter range. This algorithm uses an ESA library called CFI Software Explorer Orbit that computes altitude rate interpolating it from the satellite orbit state vector positions file at the precise time of the input measurement.

UNITS

10-2 m/s

DATA SET AVAILABILITY

Reduced: none
Standard: all
Enhanced: all

OPERATING MODE AVAILABILITY

LRM and SAR

DATA ORIGIN

1 Hz Ku/C-bands: Orbit CFI algorithm
20 Hz Ku-band: Orbit CFI algorithm
20 Hz C-band: 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]
[x1]: 1 Hz or 20 Hz data rates
[x2]: Ku-band or C-band

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
Standard: all
Enhanced: all

OPERATING MODE AVAILABILITY

LRM and SAR

DATA ORIGIN

1 Hz Ku/C-bands:Orbit CFI algorithm
20 Hz Ku-band: Orbit CFI algorithm
20 Hz C-band: 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:
[x1]: 1 Hz or 20 Hz data rates
[x2]: Ku-band or C-band

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:
open ocean or semi-enclosed seas (0b)
enclosed seas or lakes (1b)
continental ice (2b)
land (3b)

DATA SET AVAILABILITY

Reduced: 1 Hz only
Standard: 1 Hz only
Enhanced: 1 Hz only

OPERATING MODE AVAILABILITY

LRM and SAR

DATA ORIGIN

1 Hz Ku/C-bands: SRAL Level-1B product
20 Hz-Ku-band: SRAL Level-1B product
20 Hz C-band: 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