The geophysical corrections computed at Level-2 processing are:
- Model dry tropospheric corrections (zero and measurement altitudes) (mod_dry_tropo_cor_zero_altitude_[x1]_[x2]): computed from 3d meteorological fields at zero altitude, at the altimeter time-tag from the interpolation of 2 meteorological fields that surround the altimeter time-tag. A dry tropospheric correction must be added (negative value) to the instrument range to correct this range measurement for dry tropospheric range delays of the radar pulse. For (mod_dry_tropo_cor_meas_altitude_[x1]_[x2])) computed from 3d meteorological fields at measurement altitude, at the altimeter time-tag. A dry tropospheric correction must be added (negative value) to the instrument range to correct this range measurement for dry tropospheric range delays of the radar pulse.
- Model wet tropospheric corrections (zero and measurement altitudes) (mod_wet_tropo_cor_zero_altitude_[x1]_[x2]): computed from 3d meteorological fields at zero altitude, at the altimeter time-tag from the interpolation of 2 meteorological fields that surround the altimeter time-tag. A wet tropospheric correction must be added (negative value) to the instrument range to correct this range measurement for wet tropospheric range delays of the radar pulse. For (mod_wet_tropo_cor_meas_altitude_[x1]_[x2])): computed from 3d meteorological fields at measurement altitude, at the altimeter time-tag from the interpolation of 2 meteorological fields that surround the altimeter time-tag. A wet tropospheric correction must be added (negative value) to the instrument range to correct this range measurment for wet tropospheric range delays of the radar pulse.
- Composite wet tropospheric correction (comp_wet_tropo_cor_[x1]_[x2]): computed at the altimeter time-tag from both radiometer and model corrections over areas where the radiometer wet troposphere correction is missing or supposed as invalid due to the proximity of emerged lands, coastal areas and/or radiometer gaps in open oceans. A wet tropospheric correction must be added (negative value) to the instrument range to correct this range measurement fro wet tropospheric range delays of the radar pulse.
- Radiometer wet tropospheric correction (rad_wet_tropo_cor_[x1]_[x2]): a wet tropospheric correction must be added (negative value) to the instrument range to correct this range measurement for wet tropospheric range delays of the radar pulse. This correction is valid over ocean surfaces only.
- Radiometer wet tropospheric correction using SST and Gamma (rad_wet_tropo_cor_[x1]_[x2]): computed at the altimeter time-tag from the radiometer brightness temperatures, the Ku-band backscatter coefficient, the sea surface temperature and the lapse rate (decreasing rate of the atmosphere temperature with altitude). A wet tropospheric correction must be added (negative value) to the instrumetn range to correct this range measurement for wet tropospheric range delays of the radar pulse.
- Altimeter ionospheric correction on Ku band (iono_cor_alt_[x1]_[x2]): an ionospheric correction must be added (negative value) to the instrument range to correct this range measurement for ionospheric range delays of the radar pulse. This correction is valid over ocean surfaces only.
- GIM-derived ionospheric correction on Ku band (iono_cor_gim_[x1]_[x2]): an ionospheric correction must be added (negative value) to the instrument range to correct this range measurement to ionospheric range delays of the radar pulse.
- Sea state bias correction (sea_state_bias_[x1]_[x2]): a sea state bias correction must be added (negative value) to the instrument range to correct this range measurement for sea state delays of the radar pulse.
- Atmospheric attenuation correction (atm_cor_sig0_[x1]_[x2])
- Mean sea surface height above reference ellipsoid (solution 1) (mean_sea_surf_sol1_[x1]_[x2])
- Mean sea surface height accuracy (solution 1) (mean_sea_surf_sol1_acc_[x1]_[x2])
- Mean sea surface height above reference ellipsoid (solution 2) (mean_sea_surf_sol2_[x1]_[x2])
- Mean dynamic topography above goid (mean_dyn_topo_[x1]_[x2])
- Mean dynamic topography accuracy (mean dyn_topo_acc_[x1]_[x2])
- Geoid height (geoid_[x1]_[x2]): computed from the geoid model with a correction to refer the value to the mean tide system i.e. includes the permanent tide (zero frequency).
- Ocean depth / land elevation (odle_[x1]_[x2])
- Inverted barometer height correction (inv_bar_cor_[x1]_[x2]): computed at the altimeter time-tag from the interpolation of 2 meteorological fields that surround the altimeter time-tag.
- High frequency fluctuations of the sea surface topography (hf_fluct_cor_[x1]_^[x2]): provided as a correction to the inverted barometer correction (inv_bar_cor_[x1]_[x2]).
- Geocentric ocean tide height (GOT model) (ocean_tide_sol1_[x1]_[x2]): Solution 1 corresponds to GOT4.8 model. to be updated to Geocentric ocean tide height (GOT model) (ocean_tide_sol1_[x1]_[x2]): Solution 1 corresponds to GOT4.10 model.
- Geocentric ocean tide height (FES model) (ocean_tide_sol2_[x1]_[x2]): Solution 2 corresponds to FES2004 model. To be updated to "Geocentric ocean tide height (FES model) (ocean_tide_sol2_[x1]_[x2]): Solution 2 corresponds to FES2014b model.
- Equilibrium long period ocean tide height (ocean_tide_eq_[x1]_[x2]): this value has already been added to the two geocentric ocean tide height values recorded in the product (ocean_tide_sol1_[x1]_[x2] and ocean_tide_sol2_[x1]_[x2]). The permanent tide (zero frequency) is not included in this parameter because it is included in the geoid and mean sea surface (geod_[x1]_[x2], mean_sea_surf_sol1_[x1]_[x2]).
- Non-equilibrium long period ocean tide height (ocean_tide_non_eq_[x1]_[x2]): this parameter is computed as a correction to the parameter ocean_tide_eq_[x1]_[x2]. This value can be added to ocean_tide_eq_[x1]_[x2] (or ocean_tide_sol1_[x1]_[x2], ocean_tide_sol2_[x1]_[x2]) so that the resulting value models the total non equilibrium ocean tide height.
- Load tide height (GOT model) (load_tide_sol1_[x1]_[x2]): this value has already been added to the corresponding ocean tide height value recorded in the product (ocean_tide_sol1_[x1]_[x2]).
- Load tide height (FES model) (load_tide_sol2_[x1]_[x2]): this value has already been added to the corresponding ocean tide height value recorded in the product (ocean_tide_sol2_[x1]_[x2]).
- Solid earth tide height (solid_earth_tide_[x1]_[x2]): calculated using Cartwright and Tayler tables and consisting of the second and third degree constituents. The permanent tide (zero frequency) is not included.
- Geocentric pole tide height (pole_tide_[x1]_[x2])
- Rain rate (rain_rate_[x1]_[x2])
- Rain attenuation (rain_att_[x1]_[x2])
- Sea-ice concentration (sea_ice_concentration_[x1]_[x2])
- Snow density (snow_density_[x1]_[x2])
- Snow depth (snow_depth_[x1]_[x2])
PARAMETER |
Geophysical Corrections Applied to Backscatter Coefficient: Atmospheric Attenuation Correction |
NETCDF NAME |
atm_cor_sig0_[x1]_[x2] |
DESCRIPTION |
The RAD_PHY_ATT_01 algorithm computes the atmospheric attenuation correction. The Ku-band and C-band backscatter coefficient two-way atmospheric attenuations are computed from the MWR (Microwave Radiometer) 23.8 GHz and 36.5 GHz brightness temperatures (interpolated at the SRAL time tag) and from the Ku-band sigma0. |
UNITS |
10-2 dB |
DATA SET AVAILABILITY |
Reduced: none |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: RAD_PHY_ATT_01 algorithm |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
None |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
PARAMETER |
Geophysical Corrections Applied to Altimeter Range:Sea State Bias (SSB) Correction |
NETCDF NAME |
sea_state_bias_[x1]_[x2] |
DESCRIPTION |
The ALT_COR_RAN_04 algorithm computes the sea state bias. The sea state bias is the difference between the apparent sea level as "seen" by an altimeter and the actual mean sea level. A sea state bias correction must be added (negative value) to the instrument range to correct this range measurement for sea state delays of the radar pulse. |
UNITS |
10-4 m |
DATA SET AVAILABILITY |
Reduced: 1 Hz Ku-band |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: ALT_COR_RAN_04 algorithm |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
None |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
PARAMETER |
Geophysical Corrections Applied to Altimeter Range:Ionospheric Correction |
NETCDF NAME |
iono_cor_alt_[x1]_[x2] |
DESCRIPTION |
The ALT_COR_RAN_05 algorithm computes ionospheric corrections using the dual-frequency (Ku and C-bands) measurements. |
UNITS |
10-4 m |
DATA SET AVAILABILITY |
Reduced: 1 Hz Ku-band |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: ALT_COR_RAN_05 algorithm |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
Ionospheric correction derived from GIM (Global Ionospheric Maps) model(iono_cor_gim_[x1]_[x2]) |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
PARAMETER |
Mean Sea Surface Height |
NETCDF NAME |
mean_sea_surf_sol1_[x1]_[x2] (CNESCLS model) |
DESCRIPTION |
The GEN_ENV_MSS_01 algorithm computes Mean Sea Surface (mean_sea_surf_sol1_[x1]_[x2]) height above the reference ellipsoid, using CNESCLS15. The GEN_ENV_MSS_02 algorithm computes Mean Sea Surface (mean_sea_surf_sol2_[x1]_[x2]) height above the reference ellipsoid, using DTU18. |
UNITS |
10-4 m |
DATA SET AVAILABILITY |
Reduced: 1 Hz |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: 1 Hz Ku/C-bands: GEN_ENV_MSS_01 and GEN_ENV_MSS_02 algorithms |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
Mean sea surface height accuracy (mean_sea_surf_sol1_acc_[x1]_[x2] |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
PARAMETER |
Ocean Depth / Land Elevation |
NETCDF NAME |
bathy_[x1]_[x2] |
DESCRIPTION |
The GEN_ENV_BAT_01 algorithm computes the ocean depth or land elevation from a bathymetry / topography file. The model used is the global digital elevation model MACESS. If the surface type of the altimeter measurement is set to "open ocean or semi-enclosed seas", only grid points having negative altitude are used in the interpolation. If no grid points with negative altitude are found, the four grid points having positive altitude are used. If the altimeter measurement is set to "enclosed seas or lakes", "continental ice" or "land", all grid points are used in the interpolation regardless of their altitude. |
UNITS |
10-4 m |
DATA SET AVAILABILITY |
Reduced: 1 Hz |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: GEN_ENV_BAT_01 algorithm |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
None |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
PARAMETER |
Rain Rate and Rain Attenuation |
NETCDF NAME |
rain_att_[x1]_[x2] |
DESCRIPTION |
The ALT_PHY_GEN_02 algorithm computes the rain attenuation (rain_att_[x1]_[x2]). Rain attenuation is the difference between the expected main band backscatter coefficient and the measured main band backscatter coefficient. |
UNITS |
Rain attenuation: 10-2 dB |
DATA SET AVAILABILITY |
Reduced: none |
OPERATING MODE AVAILABILITY |
LRM only |
DATA ORIGIN |
1 Hz Ku/C-bands: ALT_PHY_GEN_02 and ALT_PHY_GEN_03 algorithms |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
None |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
PARAMETER |
Tide Height Corrections |
NETCDF NAME |
ocean_tide_sol1_[x1]_[x2] (GOT model) |
DESCRIPTION |
The GEN_ENV_TID_04 algorithm computes the tide height (ocean_tide_sol1_[x1]_[x2]) using the GOT4.10 model. It includes the corresponding loading tide (load_tide_sol1_[x1]_[x2]) and equilibrium long-period ocean tide height (ocean_tide_eq_[x1]_[x2]). |
UNITS |
10-4 m |
DATA SET AVAILABILITY |
Reduced: 1 Hz (GOT model only) |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: GEN_ENV_TID_03 and GEN_ENV_TID_04 algorithms |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
Non-equilibrium long period ocean tide height (ocean_tide_non_eq_[x1]_[x2]). This parameter is computed as a correction to equilibrium long period ocean tide. This value can be added to equilibrium long period ocean tide so that the resulting value models the total non-equilibrium ocean tide height. |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
PARAMETER |
Snow Density and Snow Depth |
NETCDF NAME |
snow_density_[x1]_[x2] |
DESCRIPTION |
Geo CFI and ALT_COR_RAN_06 algorithms compute snow depth, extracting it from the snow depth climatology auxiliary file and performing a bilinear interpolation. |
UNITS |
Snow density: kg/m-3 |
DATA SET AVAILABILITY |
Reduced: none |
OPERATING MODE AVAILABILITY |
SAR only |
DATA ORIGIN |
1 Hz Ku/C-bands: none |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
None |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
PARAMETER |
Geophysical Corrections Applied to Altimeter Range: Wet and Dry Tropospheric Correction |
NETCDF NAME |
mod_dry_tropo_cor_meas_altitude_ [x1]_[x2] |
DESCRIPTION |
The GEN_COR_RAN_01 algorithm computes the dry tropospheric correction at measurement altitude from meteorological models. A dry tropospheric correction must be added (negative value) to the instrument range to correct this range measurement for dry tropospheric range delays of the radar pulse. |
UNITS |
10-4 meters |
DATA SET AVAILABILITY |
Reduced: 1 Hz (dry tropospheric) and none (wet tropospheric) |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: GEN_COR_RAN_01 and RAD_PHY_GEN_02 algorithms |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
Composite web tropospheric correction (comp_wet_tropo_cor_[x1]_[x2]) is based on both radiometer and model corrections over areas where the radiometer wet troposphere correction is missing or supposed as invalid due to the proximity of emerged lands: coastal areas and/or radiometer gaps in open oceans. |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
PARAMETER |
Sea-Ice Concentration |
NETCDF NAME |
sea_ice_concentration_[x1]_[x2] |
DESCRIPTION |
Geo CFI and ALT_COR_RAN_06 algorithms compute the sea-ice concentration, extracting it from a sea-ice auxiliary file and performing a bilinear interpolation |
UNITS |
10-2 % |
DATA SET AVAILABILITY |
Reduced: none |
OPERATING MODE AVAILABILITY |
SAR only |
DATA ORIGIN |
1 Hz Ku/C-bands: none |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
None |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
PARAMETER |
Mean Dynamic Topography |
NETCDF NAME |
mean_dyn_topo_[x1]_[x2] |
DESCRIPTION |
The The GEN_ENV_MDT_01 algorithm computes Mean Dynamic Topography (MDT) above geoid. The model used is CNES/CLS 13 |
UNITS |
10-4 m |
DATA SET AVAILABILITY |
Reduced: 1 Hz |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: GEN_ENV_MDT_01 algorithm |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
Mean dynamic topography accuracy (mean_dyn_topo_acc_[x1]_[x2]) |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |
PARAMETER |
Geoid height |
NETCDF NAME |
geoid_[x1]_[x2] |
DESCRIPTION |
The The GEN_ENV_GEO_01 algorithm computes the geoid height above the reference ellipsoid. The model used is EGM2008 |
UNITS |
10-4 m |
DATA SET AVAILABILITY |
Reduced: none |
OPERATING MODE AVAILABILITY |
LRM and SAR |
DATA ORIGIN |
1 Hz Ku/C-bands: GEN_ENV_GEO_01 algorithm |
ADDITIONAL INFORMATION |
None |
PARAMETERS RELATED |
None |
PARAMETER DETAILED DESCRIPTION |
ESA's Global Land and Ocean Mission for GMES Operational Services |