S3 Product Notice Altimetry

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S3 Product Notice Altimetry Mission Sensor Product S3-A SRAL / MWR LAND L2 NRT, STC and NTC Product Notice ID Issue/Rev Date Version 1.0 Preparation S3A.PN-STM-L2L.

a Product Notice for the public release of Sentinel-3 Surface Topography Mission (STM) Level-2 Land products at Near Real Time (NRT), Short Time Critical (STC) and

1 S3 Product Notice Altimetry Mission Sensor Product S3-A SRAL / MWR LAND L2 NRT, STC and NTC Product Notice ID Issue/Rev Date Version 1.0 Preparation S3A.PN-STM-L2L Dec-2017 This Product Notice was prepared by the S3 Mission Performance Centre and by ESA and EUMETSAT experts Approval ESA Mission Management Summary This is a Product Notice for the public release of Sentinel-3 Surface Topography Mission (STM) Level-2 Land products at Near Real Time (NRT), Short Time Critical (STC) and Non Time Critical (NTC) timeliness. The Notice describes the S-3A STM current status, product quality and limitations, and product availability status. ESA page 1 / 12

2 Processing Baseline Processing Baseline IPF Processing Baseline: 2.24 IPFs version SR_1 IPF version: MW_1 IPF version: SM_2 IPF version: Current Operational Processing Baseline IPF IPF Version In OPE since SR Land Centres: MW Land Centres: SM Land Centres: NRT mode: 13/12/ :59 UTC NTC mode: 13/12/ :59 UTC NRT mode: 07/06/ :00 UTC NTC mode: 07/06/ :00 UTC NRT mode: 13/12/ :13 UTC NTC mode: 13/12/ :13 UTC ESA page 2 / 12

3 Status of the Processing Baseline The current processing baseline for Sentinel-3A STM products is reported above. The quality status of the current baseline products is as follows: o The expected performance of the ice data is not yet achieved in terms of coverage and quality but is acceptable considering the following: The S3A SRAL tracking over the continental ice margins did improve from the 7th December 2017 with the upload of a new Zone Data Base (ZDB) that changes the SRAL mode acquisition over the Greenland and Antarctica ice margins. The Level 2 algorithms have been tuned to improve data quality Improvements to the continental ice, sea-ice ground and inland processing are foreseen in the near future. The history of the processing baseline deployed in the Sentinel-3 processing centres is summarised below: Installation Date IPF Version Centre SM SM Core Ground Station Land Centre Core Ground Station Land Centre SM (current) Core Ground Station Land Centre ESA page 3 / 12

4 Known product quality limitations The Sentinel-3A STM products have some known processing limitations, which are reported in the next pages. Anomaly #1 : Duplicated measurements at 10 minutes granule transition in L2 NRT products (S3MPC-926) There are duplicates of 1 Hz measurements (same 1 Hz time tag) between consecutive granules. At granules transition, the last 1 Hz measurement and the first 1 Hz measurement of the following granule may have the same datation. In some cases, 1 Hz range values might be set to default values because there are not enough 20 Hz observations within the granule to compute the 1 Hz range. Note that the 20 Hz parameters (range, SWH and Sigma0) are not affected. Anomaly #2 : Overflow of the Ku band atmospheric attenuation in the L2 products (S3MPC- 1076) The atmospheric attenuation in Ku band is set to default values in the products when value exceeds 1.27 db. Note that for these measurements the wind speed is well calculated. Anomaly #3 : Atmospheric attenuation to default values over edges of MWR calibration (S3MPC-1077) The atmospheric attenuation on Ku band and C band is set to defaults values for sporadic points located in the fringe of the MWR calibration sequences. These isolated 1 Hz values can be found over open-ocean. As a consequence, wind speed, sea state bias, dual frequency ionospheric correction and SSHA parameters are set to default value. Anomaly #4 : SAR backscatter coefficient has an error correlated with radial velocity (S3MPC- 1251) The SAR Ku band sigma0 from ocean/coastal retracker (sig0_ocean_01_ku) shows an error correlated with radial velocities above 20 m/s. The maximum magnitude of the error is estimated to 0.2 db for the stronger velocities (25m/s). ESA page 4 / 12

5 Known product quality limitations Anomaly #5 : Error in the manoeuvre flag (EUM/Sen3/AR/2268) There is an inconsistency between the product specifications (S3IPF PDS 003 -i1r7- Product Data Format Specification - SRAL-MWR) and the effective values in the products of the manoeuvre presence flag (values set to 4 or 5 instead of 0 and 1 as specified in the documentation. Anomaly #6 : Error in Inverse Barometer correction (S3MPC-1253) There is a bias of 1 cm over open-ocean on the inverse barometer correction. Note that this error has no impact in STC and NTC products on the sum of the 2 fields used in the SSHA calculation (inverted barometer height correction (inv_bar_cor) + high frequency fluctuations of the sea surface topography (hf_fluct_cor)). Anomaly #7 : High level of retracker failure in continental ice sheets (S3MPC-1014) Over the inland ice sheets of Antarctica and Greenland there are much higher levels of the ice sheet retracker failure than found in previous missions (ie CryoSat LRM or Envisat RA2) over sloping surfaces. The anomaly on the SAR ice margin retracker also impacts the slope correction which is set to FillValue in a high number of occurrences. Improvement is observed with version reducing the loss to 20% of the data set over Antarctica. Further tuning of the SRAL L1 processing is required to insure full consistency between L1 processing and L2 ice sheet retracker, so that the expected level of ice sheet retracker coverage is finally met. Meanwhile, users are advised to use the OCOG retracker to exploit a data set with the expected coverage over land ice. Anomaly #8 : Sea Ice discrimination identifying too many floes (S3MPC-1013) A comparison of Arctic sea ice discrimination statistics during October 2016 between Sentinel- 3A and CryoSat shows that S3 processing is identifying four times more floes to leads than CryoSat s discriminator than would be expected during this period. Sentinel-3A discrimination requires further tuning. ESA page 5 / 12

6 Known product quality limitations Anomaly #9 : Large negative values in elevation over ice sheet (S3MPC-1020) Elevation values over ice sheet (elevation_ice_sheet_20_ku) are occasionally set to large negative values (in the order of m). It varies and is not the FillValue of the field. This happens particularly in the areas of ice shelves just off the coast and appears to be isolated points along the track. It does not seem to occur in the interior ice sheets or in the ocean. Anomaly #10 : Dry tropospheric correction residual error over land (S3MPC-1518) The dry tropospheric correction at the measurement altitude (mod_dry_tropo_cor_meas_altitude_01) exhibits some residual error correlated to the topography. The error has a magnitude of a few millimetres. All versions up to and including are impacted Anomaly #11 : Quantization of the distance to coast (S3MPC-1519) The distance to coast at 1 Hz and at 20 Hz exhibits some quantization. The effect is larger at 20 Hz for which the value is constant over several 20 Hz measurements. All versions up to and including are impacted Anomaly #12 : Degraded quality of atmospheric attenuation over coastal areas (S3MPC-1934) The MWR atmospheric attenuation was improved over coastal zone except for some specific cases over coastal areas, for which the attenuation is negative (-0.3 db). This anomaly affects only 0.25% of the ocean measurements and occurs when backscatter coefficient exceeds 18 db. This anomaly was introduced in version Anomaly #13 : GIM ionospheric to default value (S3MPC-2030) The GIM ionospheric correction is systematically set to default values for portions of tracks that are closed to midnight. Therefore, some of the sea ice parameters are also set to default values (sea_ice_ssha, int_ sea_ice_ssha, freeboard). for STC and NTC products ESA page 6 / 12

7 Known product quality limitations Anomaly #14 : L2 sea ice freeboard (freeboard_20_ku) is predominantly negative (S3MPC- 2244) The freeboard parameter exhibits a mean value centred around -30 cm which is not expected. The source of the error is still under investigation. Anomaly #15 : Wrong values of ssha over sea ice (S3MPC-2067) The ssha parameter over sea ice (sea_ice_ssha, int_ sea_ice_ssha) exhibits large values of 3.27 m when the GIM ionospheric correction is set to default value. The anomaly on the ssha field is due to bad handling of the default value into the ssha calculation. Anomaly #16 : SAR mode slope correction relocates echo position incorrectly (S3MPC-2074) SAR mode slope correction relocates echo position incorrectly down slope and not across track. Note that for LRM slope correction relocates echo in correct direction. Anomaly #17 : Bias between ascending and descending tracks for PLRM parameters over land ice (S3MPC-2075) There is a large ascending/descending bias present in sig0_ice_20_plrm_ku and range_ice_20_plrm_ku which are estimated by the ice2 retracker (ice erf retracker). This bias is geographically correlated and can reach up 800 m for the range and 17 db for the sigma0. The source of the error is still under investigation. Anomaly #18 : Numerical Overflow for the Waveform MQE Parameter (S3MPC-2027) There is an overflow for the waveform Mean Quadratic Error between the waveform and the model used for the ocean retracker (mqe_ocean_20_ku) in the products. This results in field padded to default value over sea ice in Antarctica and Arctic and sporadically over open ocean. ESA page 7 / 12

8 Known product quality limitations Anomaly #19 : Numerical Overflow for the peakiness parameter (S3MPC-2028) There is an overflow for the peakiness parameters (peakiness_2_20_ku, peakiness_2_20_c, peakiness_1_20_plrm_ku) in the products. This results in fields padded to default value over sea ice in Antarctica and Arctic where peaky waveforms can happen. ESA page 8 / 12

9 Products Availability Copernicus Open Access Hub ( NRT and NTC FTP server address login: login password: password Other Any other useful information The baseline collection number in the products filename changed from 2 to 3 to reflect the major evolutions introduced by this Processing Baseline. As an example, the filename for STC products will be labelled as O_ST_003.SEN3 instead of O_ST_002.SEN3 The brightness temperatures exhibit a difference of up to 1 K between ascending and descending tracks for the 23.8 GHz channel. Work is ongoing to understand the source of this difference. The composite wet tropospheric correction has not been calibrated yet and should not be used (comp_wet_tropo_cor_01_ku and comp_wet_tropo_cor_01_plrm_ku). During MWR calibrations over open-ocean, the brightness temperatures for both channels are not computed and set to default values in the product. As a consequence, 1 Hz parameters derived from the MWR are set to default values, except for the atmospheric attenuation. This affects the wet tropospheric correction, water vapour content and cloud liquid water content. The Ku band sigma0 in all modes (LRM, PLRM and SAR) has been biased to be aligned on Envisat mean value (10.8 db without the atmospheric attenuation). A system bias of db was applied to SARM Ku band and of -2 db to the LRM and PLRM Ku band. Note that the sigma0 derived from ice sheet retrackers exhibits a mean value close to 42 db The C-band sigma0 in all modes (LRM and PLRM) has not been biased and exhibit a mean value around 11 db which is lower by 4 db compared to Jason-2. Since version 06.10, sigma0 is now corrected for atmospheric attenuation. The higher noise of the C band range inherent to the PLRM processing contributes to a high noise in the dual frequency ionospheric correction. The SAR Ku band SWH from SAMOSA retracker shows a smaller bias thanks to the implementation of SAMOSA 2.5 retracker. Nevertheless, an error correlated to SWH is still present when compared to PLRM observations and Jason-3 observations, ranging from -5 cm for low waves to 15 cm for the stronger waves. The SAR range values haven been improved thanks to the implementation of SAMOSA 2.5 retracker. We observe now a discrepancy reduced to 0.3%SWH for waves greater than 4 m, compared to PLRM and Jason-3 observations. Note that the SSB correction has not been ESA page 9 / 12

10 Any other useful information tuned for Sentinel-3A and contains Jason-2 SSB solution. The rain flag is presently based on Envisat flag and it has not been tuned for Sentinel-3A mission. The ocean/sea ice flag is presently based on Envisat flag and it has not been tuned for Sentinel- 3A mission. The ice-sheet snow facies type flag is presently based on Envisat flag and it has not been tuned for Sentinel-3A mission. There was a change of version of the ECMWF model on 11 July. All the changes are described in the following note (ref. S3MPC.ECM.MEM.045, dated on 7-Jul-17). References Product Data Format Specification - SRAL/MWR Level 1 & 2 Instrument Products, Ref: S3IPF.PDS.003, Issue: 2.9, Date: 15/11/ Static ADFs updated The following list is the complete list of static ADF used by the processor. Any change from the previous processing baseline will be highlighted in red. S3A_SR_2_CCT_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3A_SR_2_IC01AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3A_SR_2_IC02AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3A_SR_2_IC03AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3A_SR_2_IC04AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3A_SR_2_IC05AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3A_SR_2_IC06AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3A_SR_2_IC07AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3A_SR_2_IC08AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3A_SR_2_IC09AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3A_SR_2_IC10AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3A_SR_2_SSBLAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3A_SR_2_SSBSAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_CP00AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_CP06AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_CP12AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_CP18AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_EOT2AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3 SR_2_FLT_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_GEO_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_LNEQAX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 ESA page 10 / 12

11 Static ADFs updated S3 SR_2_LRC_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_LT2_AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3 SR_2_LUTEAX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3 SR_2_LUTFAX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3 SR_2_LUTSAX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3 SR_2_MAG_AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3 SR_2_MDT_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_MLM_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_MSMGAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_MSS1AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3 SR_2_MSS2AX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3 SR_2_ODLEAX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3 SR_2_RET_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_RRC_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_S1AMAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_S1PHAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_S2AMAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_S2PHAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD01AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD02AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD03AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD04AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD05AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD06AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD07AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD08AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD09AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD10AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD11AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SD12AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SET_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SFL_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SHD_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI01AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI02AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI03AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI04AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI05AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI06AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI07AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI08AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI09AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI10AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI11AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SI12AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SIGLAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SIGSAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SSM_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SST_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_SURFAX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3 SR_2_WNDLAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_WNDSAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_CON_AX_ T000000_ T235959_ T MPC_O_AL_009.SEN3 S3 SR_2_EOT1AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR_2_LT1_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 AX CST_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3 SR LSM_AX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3A_SR CHDRAX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3A_SR CHDNAX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 S3A_MW CHDRAX_ T000000_ T235959_ T MPC_O_AL_001.SEN3 S3A_MW CHDNAX_ T000000_ T235959_ T MPC_O_AL_002.SEN3 ESA page 11 / 12

12 End of the Product Notice ESA page 12 / 12

Copernicus S3 Product Notice Altimetry

Copernicus S3 Product Notice Altimetry Mission Sensor Product S3 SRAL / MWR LAND L2 NRT, STC and NTC Product Notice ID S3A.PN-STM-L2L.08 Issue/Rev Date 14-Feb-2019 20-Mar-2019 Version 1.1 Preparation This