living planet symposium

Transcription

1 living planet symposium!!the Sentinel-3 Surface Topography!!Mission and Products C. Mavrocordatos ESA-ESTEC (Netherlands) P. Féménias ESA-ESRIN (Italy) N. Picot CNES (France) H. Bonekamp EUMETSAT (Germany)

2 Topography Mission Payload! SRAL "! Dual freq. C & Ku-band radar altimeter "! 2 measurement modes:! LRM, conventional pulse-limited mode! SAR, high along-track resolution (300m) "! 2 tracking modes: open or closed-loop "! Technology inherited from CryoSat and Jason-2 "! Instrument Prime: Thales France Toulouse! MWR "! Dual freq & 36.5 GHz "! Noise injection radiometer, with cold sky calibration "! Technology inherited from Envisat "! Instrument Prime: Casa Spain! POD Instruments "! Dual-freq. GPS receiver, RUAG - Austria "! DORIS navigation receiver, CNES/TSA - France "! Laser Retro-Reflector 2"

3 Topography Mission Overview! Measurements "! Sea Surface Height "! Significant Wave Height "! Wind Speed "! Sea Ice thickness (freeboard) "! Ice Sheet surface elevation "! Inland Water surface elevation "! Atmosph. Water Content! Observed Surfaces 3"

4 Topography Mission - Operations #! SRAL modes vs observed surfaces Surface type Measurement mode Tracking mode Open ocean LRM (optionally SAR) Closed loop Coastal zones SAR Open loop/closed loop Sea ice SAR Closed loop Ice sheet interiors LRM (optionally SAR) Ice sheet margins SAR Closed loop Open loop In-land water SAR Open loop 4"

5 Topography Mission - Performance SAR vs LRM performance over Ocean " based on CryoSat (red/blue) and Jason-2 (black) data!!all modes perform similarly for wavelengths larger than 100 km. SARM is not affected by any error in the medium/large mesoscale band. "!For wavelengths 7 to 100 km: the black (LRM) and blue (pseudo-lrm) spectra exhibit a spectral "bump", the red spectrum (SARM) does not"!a white noise plateau is visible on all spectra for wavelengths from 600 m to approx. 3 km. The blue spectrum (pseudo- LRM) is largely higher than Jason-2 (sqrt3 as expected). The SAR spectrum (red) exhibits a white noise plateau lower than Jason-2's (by approximately 30%). " SAR mode measurements seem more accurate than LRM for scales <100km" 5"

6 Topography Mission - Performance SAR vs LRM performance over Ocean (cont d)" -! SAR " -! Reduced SAR (Pseudo-LRM)" -! SAR 20km smoothed" Small scale signals present on the surface seem to be smoothed by the 20km LRM footprint" See dedicated presentation in next session by N.Picot et al " 6"

7 SRAL Operation 100% SAR option #! SAR mode performance over Ocean offers significant benefits over LRM, as demonstrated by CryoSat #! EC requested ESA (Nov. 22, 2012) to analyse the possible extension of SAR mode operation up to 100% of Earth coverage #! Current situation "!Preliminary analysis identified no technical show stopper "!A further option, making available additional L1B products relevant to SAR mode was identified and included in the assessment "!EC requested to proceed with a detailed analysis "!Implementation will be decided based on cost/schedule 7"

8 Topography Mission Ground Tracks "! Sentinel-3 ground tracks have been recently defined, considering in particular external calibration req. for the Topography Mission. " "! The new ground tracks offer a triple cross-over over Crete between S3A, S3B and Jason" "! A calibration site hosting a transponder is being established on this point" See dedicated paper by S.Mertikas et al presented in Altimetry Cal/Val (Monday session)" 8"

9 Topography Mission Ground Tracks Sentinel-3A and -3B ground tracks can be downloaded in Google Earth KML format from: sentinel.esa.int! 9"

10 Instruments SRAL status #! SRAL PFM development is complete and the instrument is currently under mechanical integration into the spacecraft. SRAL PFM mechanical integration in the satellite" Final functional tests in Toulouse, with antenna provisionally connected in front of the RF wall EGSE " 10"

11 SRAL PFM performance Impulse Response function (CAL-1)" Ku-band/SAR-mode/Nominal chain!! 0!5!10 Impulse Response ( Ku!Band ) mode : SAR I,Q Side lobe threshold Ideal side lobes IR Ideal IR!15!20 0!5 Impulse Response ( Ku!Band ) mode : SAR I,Q Normalized level (db) Side lobe threshold Ideal side lobes IR Ideal IR!25!30!10!35!40!15 Normalized level (db)!20!45!50!1000! Frequency (khz)!25!30!35 => very close to theoretical sinc function!!40!150!100! Frequency (khz) 11"

12 SRAL PFM performance Receive chain amplitude response (CAL-2)"! Average, Ku!Band Average (db) 0 0.8!0.5!1 0.7!1.5!2 0.6!2.5!3 0.5! !1000! Average, Ku!Band! No spurious spikes!! Ripple within spec and as expected! Zoom (db) !1000!800!600!400! Frequency (khz) 12"

13 SRAL performance Tracking performance" " " " " green: altitude variation of the test scenario" red: SRAL PFM tracking window position" " " " " blue: altitude difference" " " " => Tracking performance (noise/lag) as expected! m !50! !150! ! Time (s) 0.5! !10!11 0.2!12 m!9!13 0.1!14 Altitude variation (Initial altitude : m) Altitude difference Scenario altitude Altimeter altitude command Altitude difference! ! Time (s)! 13"

14 Instruments MWR status #! MWR PFM test campaign in IABG completed end of August, including mechanical vibrations, thermal vacuum (TB/TV), Instrument performance calibration in vacuum MWR PFM & cold loads entering the vacuum chamber" MWR PFM being prepared for calibration with the installation of cold loads " 14"

15 MWR vibration tests 15"

16 MWR Performance Sensitivity/Accuracy Stability Allan STD GHz 23.8 GHz (Earth observation) NO BLK 10-1 K 116 K K Earth observation (I) samples 36.5 GHz (Earth observation) NO BLK Time (s) Allan STD GHz Earth observation (I) samples Accuracy: Ta - Temp Target (Earth observation) K GHz 36.5 GHz 10-2 K Earth observation (I) samples Time (s) Typical test conditions/results: "! Receiver temperature: 25 C"! Target temp. (uncorrected): 76.9 / C"! Allan variance is decreasing for the complete measurement period showing an extremely high stability of the MWR electronics and the target temperature." 16"

17 POD Instruments - status GNSS receiver/antenna integration Doris receiver mounted on a satellite panel (right) and Doris antenna and LRR (top) mounted on the spacecraft 17"

18 Products generation Level 1 products (baseline: internal products)! SRAL & MWR L1B products! Generated by ESA/EUMETSAT! Internal products Level 2 Marine User products! STM L2 Marine product SR_2_WAT! Generated by EUMETSAT at PDGS Marine Center Measurements included in the MARINE product Measurements included in the LAND product Level 2 Land User products! STM L2 Land product SR_2_LAN! Generated by ESA at PDGS Land Center S-3 STM L2 production organisation Land and Water masks are in overlap to ensure analysis of transition and meaningful continuity of segments!! 300Km over ocean 10 km over land Marine product: information sensed over open ocean, coastal areas, sea-ice + mask margin Land product: information sensed over land, coastal areas, land ice and inland water + mask margin 18"

19 Products Timeliness T0 Sensing time 3 h 2-3 d ~30 d ~every 1-2 y time NRT products Ocean forecasting, Meteorology, Oceanography STC products Operational Ocean, Ocean forecasting, Oceanography NTC products Climatology, Oceanography, Data exploitation NRT: Near Real time STC: Slow Time Critical NTC: Non time Critical Reprocessing Campaign (only NTC products) 19"

20 L2 baseline Products 1 Hz LRM/SAR Ku/C Data Set 1 Hz LRM/SAR Ku/C Data Set 1 Hz LRM/SAR Ku/C Data Set 37';0./%21%<#$%=7:&%'()*% +(,(-./.,0%1,2-%3456% -.(07,.-.)/0%+.,12,-.*%8)% 649:354%92*.0 <#$%=7:&%'()*%+(,(-./.,0%1,2-% 3456%-.(07,.-.)/0%+.,12,-.*% 8)%649:354%92*.0 <#$%=7:&%'()*%+(,(-./.,0%1,2-% 3456%-.(07,.-.)/0%+.,12,-.*% 8)%649:354%92*.0!"#$%&'()%*+,-%./+0'1/./,2% $ 1Hz Reduced Measurement Data File 20 Hz LRM/SAR_C Data Set!"#$%&%'()*%+(,(-./.,0%1,2-% 3456%-.(07,.-.)/0%+.,12,-.*% 8)%649:354%92*.0 20 Hz LRM/SAR_C Data Set!"#$%&%'()*%+(,(-./.,0%1,2-% 3456%-.(07,.-.)/0%+.,12,-.*% 8)%649:354%92*.0!"#$%&'()%*+,-%./+0'1/./,2% 20 Hz LRM/SAR_Ku Data Set 20 Hz LRM/SAR_Ku Data Set!"#$%=7%'()*%+(,(-./.,0%1,2-% 3456%-.(07,.-.)/0%+.,12,-.*% 8)%649:354%92*.0!"#$%=7%'()*%+(,(-./.,0%1,2-% 3456%-.(07,.-.)/0%+.,12,-.*% 8)%649:354%92*.0 $ 1Hz + 20 Hz Standard Measurement Data File Waveforms waveforms and associated parameters to reprocess the data (at least in LRM)!"#$%3+4/561.0% $! 1Hz + 20 Hz + WF Enhanced Measurement Data File 20"

21 Future L1 user products! L1 Products identified to become operational on Sentinel-3:! L1A: Unpacked L0 complex echoes that have been sorted and calibrated. Geo-location information is also included. Product relevant to SAR processing specialists allowing fundamental studies on SAR processing such as Doppler beam formation and for calibration studies using ground-based Transponders.! L1B-S: Geo-located, calibrated azimuth formed complex (I and Q) echoes related to a given location on the ground, after slant range correction. No averaging of individual waveforms (i.e.multi-looking/stacking) is applied. Relevant ancillary data (e.g. beam angles, calibration information, statistical description of the multi-looked average/stack etc) is included. Product relevant to geophysical retrieval algorithm developers (over ocean, land and ice surfaces), surface characterisations studies (e.g. impact of sea state bias, wave directional effects etc) and Quality Control systems.! L1B: Geo-located, calibrated, azimuth formed, slant range corrected and averaged together (i.e multi-looked/stacked) power echoes associated with a fixed point on the ground-track. This product is relevant to geophysical retrieval algorithm developers and Quality Control systems. 21"

22 Future L1 user products L1A" L1B-S" L0" calibration Azimuth FFT (beam formation) Sorting and migration correction Multilooking L1B" 22"

23 Conclusion "! Topography Mission Instruments development is complete and integration/ tests in the Sentinel-3A spacecraft are currently in progress" "! Sentinel-3B Topography payload is well advanced and delivery of the last instrument is expected in spring 2014" "! Performances are fully in line with expectations" "! Further improvements of the Topography mission -with respect to the original baseline- are considered for implementation:"!! 100% SAR operation" Additional Level1User Products" 23"