Altimeter standards

Product standard ref

• Topex/Poseidon :  GDR-F

• Jason-1 : GDR-D

• Jason2 : GDR-F

• Jason-3 : GDR-F

• ERS-1 : -

• ERS-2 : -

• Envisat : -

• SARAL-DP/AltiKa: -

• Sentinel-6A : F09

• Sentinel-3A/B : BC05

• Geosat Follow On : -

• Cryosat-2: -

• HaiYang-2A : NSOAS

• HaiYang-2B : NSOAS

• SWOT-nadir : GDR-F

Retracking

• Topex/Poseidon :  MLE3

• Jason-1/2/3 : MLE4

• ERS-1/2 : OPR

• Envisat : MLE3 (OCE1)

• SARAL-DP/AltiKa: MLE4

• Sentinel-6A : Numerical LRM

• Sentinel-3A/B : SAMOSA

• Geosat Follow On : GFO retracker

• Cryosat-2: SAMOSA 2.3

• HaiYang-2A/B : MLE4

• SWOT-nadir : MLE4

Orbit

• Topex/Poseidon :  GSFC STD18

• Jason-1/2/3 : POE-F

• ERS-1/2 : Reaper

• Envisat : POE-F

• SARAL-DP/AltiKa: POE-F

• Sentinel-3A/B, Sentinel-6A : POE-F

• Geosat Follow On : GSFC

• Cryosat-2: POE-F

• HaiYang-2A : POE-D

• HaiYang-2B : POE-F

• SWOT-nadir : POE-F

Environemental corrections

Sea State Bias

• Topex/Poseidon :  2D Non parametric (Putnam et al., 2023) on Topex; BM4 on Poseidon 

• Jason-1: 2D Non parametric (Tran, 2015)

• Jason-2: Non parametric (Tran et al., 2012)

• Jason-3: 2D Non parametric (Bignalet-Cazalet et al., 2021)

• ERS-1: BM3 (Gaspar and Ogor, 1994)

• ERS-2: Non parametric (Mertz et al., 2005)

• Envisat : 2D non parametric (Tran, 2017)

• SARAL-DP/AltiKa: non parametric (Tran, 2019)

• Sentinel-6A: Non Parametric (Bignalet-Cazalet et al., 2021) J3 MLE4 GDR-F

• Sentinel-3A/B : Non parametric (Tran,et al 2021)

• Geosat Follow On : Non parametric  (Tran et al., 2010)

• Cryosat-2: 2D Non parametric (baseline C) (Tran, 2018)

• HaiYang-2A: Non parametruc from J3 MLE4 (Bignalet-Cazalet et al., 2021)

• HaiYang-2B:  From L2 product

• SWOT-nadir: Non parametruc from J3 MLE4 (Bignalet-Cazalet et al., 2021)

High Frequency Adjustment 

All missions : none

Ionospheric

• Topex/Poseidon :  Filtered dual-frequency altimeter range measurements  (Ablain and Legeais, 2010) on Topex ; DORIS on Poseidon

• Jason-1 : Filtered dual-frequency altimeter range measurements (Guibbaud et al., 2015)

• Jason2 : Filtered dual-frequency altimeter range  (Guibbaud et al., 2015) (from SSB C-band)

• Jason-3 : Filtered dual-frequency altimeter range measurements GDR-F (Nencioli et al., 2022)

• ERS-1 : - Reaper NIC09 model (Scharroo and Smith, 2010)

• ERS-2  : GIM (Iijima et al., 1999)

• Envisat : Filtered from L2; c>65 : GIM (Iijima et al., 1999) corrected for 8mm bias

• SARAL-DP/AltiKa : GIM (Iijima et al., 1999)

• Sentinel-6A : Filtered dual-frequency altimeter range (Guibbaud et al., 2015)

• Sentinel-3A/B : Filtered dual-frequency altimeter rangefrom L2

• Geosat Follow On : GIM (Iijima et al., 1999)

• Cryosat-2: GIM (Iijima et al., 1999)

• HaiYang-2A/B: GIM (Iijima et al., 1999)

• SWOT-nadir : Filtered dual-freq altimeter range (Guibbaud et al., 2015)

Dry troposphere

All missions: ERA5 (10-hour) model based

Wet troposphere

• Topex/Poseidon :  TMR GDRF radiometer reprocessing

• Jason-1: JMR (FCDR) radiometer 

• Jason-2/3: AMR radiometer GDR-F

• ERS-1/2 : GPD+ (Fernandes et al., 2015)

• Envisat : MWR radiometer reprocessed

• SARAL-DP/AltiKa: Neuronal Network (5 entries) V4

• Sentinel-6A: AMR radiometer

• Sentinel-3A/B : GPD+ (Fernandes and Lázaro, 2016)

• Geosat Follow On : GFO Radiometer and ECMWF model

• Cryosat-2: GPD+ (Fernandes and Lázaro, 2016)

• HaiYang-2A/B,  SWOT-nadir: ECMWF model

Geophysical corrections

DAC

All missions: TUGO High frequencies forced with analysed ERA5 pressure and wind field before S6A era and ECMWF field after + inverse barometer LF

Ocean tide

All missions: FES22b (Loren Carrère et al., 2023)

Internal tide

All missions: (Zaron, 2019) (HRETv8.1 tidal frequencies: M2, K1, S2, O1)

Pole tide

All missions: (Desai et al., 2015); Mean Pole Location 2017 (Ries and Desai, 2017)

Solid earth tide

All missions: Elastic response to tidal potential (Cartwright and Edden, 1973; Cartwright and Tayler, 1971)

Loading tide

All missions: FES2014 (Carrere et al., 2016)

GIA

All missions: The DUACS products are not corrected from Glacial Isostatic Adjustment (GIA) effects

Reference surfaces

Mean Profile/ Mean Sea Surface

• Topex/Poseidon , Jason-1/2/3 repetitive phase: MP computed with Topex/Poseidon (January 1993, April 2002; cycles 11 to 353), Jason-1 (April 2002, October 2008; cycles 10 to 249); Jason-2 (October 2008, May 2016; cycles 10 to 290), Jason-3 (May 2016, December 2021; cycles 11 to 217) and Sentinnel-6A (December 2021, August 2023; cycles 42 to 103) measurements. Referenced to the [1993, 2012] period.
  Topex/Poseidon , Jason-1/2 interleaved phase: MP computed with Topex/Poseidon interleaved (September 2002, October 2005; cycles 368 to 481), Jason-1 interleaved (February 2009, March 2012; cycles 262 to 374), Jason-2 interleaved (October-2016; March-2017; cycles 305 to 322).and Jason-3 interleaved (April 2024, August 2023; cycles 300 to 350) measurements. Referenced to the [1993, 2012] period.
  Jason-1/2 LRO phase : Hybrid_2023 MSS (SIO,CNES/CLS22,DTU21) (Laloue et al., 2024)

• ERS-1/2: MP computed with with ERS-2 (May 1995, January 2000; cycles 1 to 49), Envisat (May 2002, October 2010; cycles 6 to 94) and SARAL/Altika (Mars 2013, Mars 2015; cycles 1 to 22) measurements. Referenced to the 1993-2012 period.

• Envisat, SARAL-DP/AltiKa repetitive phase: MP computed with computed with with ERS-2 (May 1995, January 2000; cycles 1 to 49), Envisat (May 2002, October 2010; cycles 6 to 94) and SARAL/Altika (Mars 2013, Mars 2015; cycles 1 to 22) measurements. Referenced to the 1993-2012 period. 
  Envisat, SARAL-DP/AltiKa geodetic phase: Hybrid_2023 MSS (SIO,CNES/CLS22,DTU21) (Laloue et al., 2024)

• Sentinel-3A: MP computed with Sentinel-3A (June 2016, August 2023; cycles 6 to 103). Referenced to the 1993-2012 period
  Sentinel-3B: MP computed with Sentinel-3B (November 2018, August 2023; cycles 19 to 83. Referenced to the 1993-2012 period

• Geosat Follow On: MP computed with Geosat Follow On (January 2000, September 2008; cycles 37 to 222) measurements. Referenced to the [1993, 2012] period.
  Cryosat-2, HaiYang-2A/B, SWOT-nadir: Hybrid_2023 MSS (SIO,CNES/CLS22,DTU21) (Laloue et al., 2024) 

Mean Dynamic Topography

All missions: Global: MDT_CNES_CLS22 (Jousset et al., 2023) merged with regional MDT CMEMS_2020 Mediterranean and Black Sea (Jousset et al., 2022; Jousset and Mulet, 2020); Europe: MDT Europe CMEMS_2024 (Jousset et al, in prep)