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Www.argans.co.uk SMOS L2 Ocean Salinity Level 2 Ocean Salinity QWG #4 7-9 March 2011 ARGANS & L2OS ESL.

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Presentation on theme: "Www.argans.co.uk SMOS L2 Ocean Salinity Level 2 Ocean Salinity QWG #4 7-9 March 2011 ARGANS & L2OS ESL."— Presentation transcript:

1 SMOS L2 Ocean Salinity Level 2 Ocean Salinity QWG #4 7-9 March 2011 ARGANS & L2OS ESL

2 SMOS L2 Ocean Salinity Level 1 fixed cal reprocessing analysis (presentation by J. Tenerelli) – Drift (impact of TP7 correction) – Sun impact LO decimation study (TN/presentation by J. Font) Radiometric accuracy & sun flags (presentation by X. Yin) OTT drift and quality analysis OTT sensitivity study: – impact of galaxy signal, num. snapshots, time window (BEC PM#20) Outliers detection to identify RFI Upgrading roughness models – Rough 1: foam effect added, change in surface spectrum – Rough 2: going to an empirical roughness correction – Rough 3: improving LUT, going to fully empirical model Scientific status

3 SMOS L2 Ocean Salinity L2OS status 27 December January February 2011 L2OS 0316 enters its 9 th month of processing in DPGS...

4 SMOS L2 Ocean Salinity 317 history – delivered 22 November 2010; FAT passed 7 December 2010 – January installation delayed (L1OP not available) – new roughness model 3 LUT & OTTs for January calibration delivered early February – management meeting 9 February approves installation 317 – February IDEAS reject 317 due to AUX_BULL_B validity period issues (40+ s) – go-ahead for 317 to be installed in DPGS March... Issues: – L2OS ESL lose 2+ months pre-reprocessing DPGS data analysis – L2OS processor development/testing for summer delivery still using L1OP 34x no L1c 35x with correct RFI flags yet! 500 history? L2OS status

5 SMOS L2 Ocean Salinity New roughness 3 LUT SM_TEST_AUX_RGHNS3_ T000000_ T000000_001_012_8 (19/11/2010)

6 SMOS L2 Ocean Salinity New roughness 3 LUT SM_TEST_AUX_RGHNS3_ T000000_ T000000_001_013_8 (21/01/2011)

7 SMOS L2 Ocean Salinity Outlier test: – abs((Tbmeas - Tbmodel) - correction) > nsig. sigmaTb ATBD: – correction = median (Tbmeas - Tbmodel) DPM & 0317: – correction = median (Tbmeas) – median(Tbmodel) Outlier detection

8 SMOS L2 Ocean Salinity Outlier detection TN analysis prepared by Claire Henocq, Jean-Luc Vergely & Jacqueline Boutin

9 SMOS L2 Ocean Salinity Outlier detection No longer considered outliers New outliers TN analysis prepared by Claire Henocq, Jean-Luc Vergely & Jacqueline Boutin

10 SMOS L2 Ocean Salinity Outlier detection Number of outliers plotted against longitude (0317), latitude +- 1 degree total outliers 8477, 1570 grid points

11 SMOS L2 Ocean Salinity Outlier detection Number of outliers plotted against longitude (0318), latitude +- 1 degree total outliers 7802, 1570 grid points

12 SMOS L2 Ocean Salinity Outlier detection: SSS delta ( ) SM_OPER_MIR_SCSF1C_ T153816_ T163215_344_001_1

13 SMOS L2 Ocean Salinity Outlier detection: Dg_num_outliers delta ( ) SM_OPER_MIR_SCSF1C_ T153816_ T163215_344_001_1

14 SMOS L2 Ocean Salinity L1 & L2 RFI flags L2 fm_l1c_rfi set if any of L1c flags set: – fml1c_rfi_mitigation – fml1c_rfi_strong – fml1c_rfi_point L2OS 0317 sets fm_valid = false if fm_l1c_rfi set Some orbits may have L1 RFI flags set over a wide area, eg SM_TEST_MIR_SCSF1C_ T080748_ T090119_350_001_0 So L2OS 0317 will find too few measurements for many grid points, leading to missing salinity retrievals

15 SMOS L2 Ocean Salinity L1 & L2 RFI flags few outliers? SM_TEST_MIR_SCSF1C_ T080748_ T090119_350_001_0

16 SMOS L2 Ocean Salinity Rain Rate ECMWF rain rate is metres/hour (10 3 litres per m 2 per hour), not mm/hr Max values are typically in storms. AUX_CNFOSD/F sets Tg_max_rainfall = 2, so Fg_sc_rain is never set ECMWF Rain_Rate Fg_sc_rain (Tg_max_rainfall = 0.002)

17 SMOS L2 Ocean Salinity Presentation by J. Tenerelli: land contamination Radiometric accuracy & sun flags (presentation by X. Yin) RFI detection (presentation by P. Spurgeon)

18 SMOS L2 Ocean Salinity Validation of current DPGS L2OS Using L3 operationally generated by CP34 – SMOS SSS (10 days L3 product) – WOA2005 SSS (climatology for February)

19 SMOS L2 Ocean Salinity – SMOS SSS (10 days L3 product) – Argo at -7.5 m (same period) Bias 0.26 psu STD 0.81 psu Still a lot to improve!

20 SMOS L2 Ocean Salinity Towards reprocessing L2OS upcoming improvements for (May/June) delivery (v500) – RFI detection/mitigation Fg_ctrl_suspect_RFI (no impact on schema), Dg_num_RFI_outliers (UDP schema change) switch RFI detection on/off, add threshold(s) to AUX_CNFOSD/F – roughness model & configuration tuning ICM empirical model without flat sea - analysis and algorithm design: CRR impact assessment N/A – fixed PRs: outlier detection ATBD/DPM mis-match – detected 1 February mis-use of L1 RFI flags – detected 27 January wrong ECMWF rain rate units & Tg_max_rainfall/Fg_sc_rain – detected 4 February BULL_B validity issues – detected 18 February On-going studies – errors in ECMWF WS (compared to SSMI) lead to bias in SSS – work continuing – investigate sun/galactic glint models (mismatch with SMOS data)

21 SMOS L2 Ocean Salinity ECMWF/SSMI WS: example of difference

22 SMOS L2 Ocean Salinity ECMWF/SSMI WS: Average SSSsmos-SSSargo in classes of 1m/s of WSecmwf-WSssmi WSecmwf-WSssmi (m/s)

23 SMOS L2 Ocean Salinity Time series & site statistics site monitoring: S. Pacific

24 SMOS L2 Ocean Salinity Site monitoring: S. Pacific (ascending)

25 SMOS L2 Ocean Salinity Site monitoring: S. Pacific (descending)

26 SMOS L2 Ocean Salinity Site monitoring: S. Pacific SSS1/2 correlation

27 SMOS L2 Ocean Salinity SMOS, ARGO (August 2010) & CLIMATOLOGICAL SSS Colocation +/- 5 days, +/-50km, center swath +/-300km, Ascending orbits

28 SMOS L2 Ocean Salinity SMOS Model 1 - ARGO SSS (3-31 August 2010; asc orbits) versus wind speed (center of orbit)

29 SMOS L2 Ocean Salinity OTT/drift analysis Objective – determine OTT drift & required update frequency Analyse DPGS L2OS 316 salinity drift in stable South Pacific zone (0-30S) – retrieved salinity with sigma_SSS error – SSS anomaly (retrieved – climatology) Generate new OTT with 0317 for 0, +1, +2, +4, +7, +13, +28, +43 days – 02/08/2010, 03/08/2010, 04/08/2010, 06/08/2010, 09/08/2010, 15/08/2010, 30/08/2010, 14/09/2010 Compare DPGS L2OS 0316 SSS drift with new OTT drift Reprocess reference orbit 02/08/2010 with 0317 & new OTT – plot SSS & anomaly drift

30 SMOS L2 Ocean Salinity DPGS 0316 drift, Aug-Dec 2010 Selected South Pacific orbits, 0-30S, xswath ±300km, unfiltered, with sigma_SSS

31 SMOS L2 Ocean Salinity DPGS day drift Selected South Pacific orbits, SSS – climatology, 0-30S, xswath ±300km, unfiltered

32 SMOS L2 Ocean Salinity OTT drift OTT1 delta for selected South Pacific orbits 0-30S, 03/08/2010 to 29/11/2010

33 SMOS L2 Ocean Salinity Correlation between OTT & DPGS drift OTT delta versus mean SSS for selected South Pacific orbits 0-30S

34 SMOS L2 Ocean Salinity Reprocessing ref orbit with new OTT orbit reprocessed 0317 with OTT from later dates

35 SMOS L2 Ocean Salinity OTT/drift analysis discussion Purpose of OTT: – correct L1c TBs so L2OS can retrieve good quality salinity – secondary role: diagnostic for L1c quality Issues – Wait for L1OP 350 & 317 in DPGS to analyse OTT correction? – Wait for L1PP 500 & L2OS 500 June 2011 & analyse drift/OTT impact? – Perform analysis on fixed cal reprocessed commissioning data? Analysis strategies – Routine generation of OTT drift statistics? – UDP SSS anomalies or other metrics (eg time-series statistics, collocation match-ups) – Other? OTT strategies – One per day/week/month etc (eg mid-week – good for commissioning data) from a single orbit average of several orbits – eg one ascending & one descending abrupt transition between OTTs or smoothed – running average? – One size fits all – single OTT for entire reprocessing?

36 SMOS L2 Ocean Salinity Algorithm validation Once new L1 500 and L2OS 500 are implemented in DPGS, we will check: – Effectiveness of OTT strategy – Ascending/descending differences – Land contamination – RFI properly removed – Impact of sun and galactic signals – Performance of new roughness models. Comparison of SMOS to Argo and climatology Timetable?

37 SMOS L2 Ocean Salinity Decisions proposed to QWG #4 Increasing LO calibration frequency RFI outlier detection at L2OS Removing sun correction at L1 Extend L1 SUN_POINT flag to a circle around sun Flagging suspenders at L1

38 SMOS L2 Ocean Salinity 38 Remembering SSS requirements R The accuracy of the ocean salinity data products with a 50 km spatial resolution shall be <= 1.2 PSU. Note: This OS Level-2 accuracy requirement corresponds to : · snapshot images (100) of one pixel taken during one single pass, · usage of the narrow swath, · full spatial coverage, · ocean temperature of 277 K G The accuracy of the ocean salinity maps outside coastal areas, after averaging over 200 km x 200 km x 10 days space-time domain, shall be <= 0.1 PSU, after corrections by using vicarious calibration, namely by periodical imaging of one or more well-known reference sources.

39 SMOS L2 Ocean Salinity 39 On statistics During 10 minutes 500 SMOS snapshots are acquired Calibrating LO every 10 min means loosing 5 snapshots, then the error in building an L3 map by averaging L2 products (wrt no calibration) increases by sqrt (500)/sqrt(495) = Calibrating every 2 min, 25 snapshots are lost, the L3 error increases by sqrt(500)/sqrt(475) = Going back to one orbit, the increase of usable min compared min implies an error reduction of sqrt(495)/ sqrt(475) = 1.02 This 2% reduction on the required SSS error means 0.02 psu We showed that min instead min implies an error reduction by 0.2 psu (clean Pacific), 0.5 psu in global average

40 SMOS L2 Ocean Salinity AOB NIR 2 week calibration impact on salinity TBD ascending/descending? Monitoring products

41 SMOS L2 Ocean Salinity Solar flare? SM_OPER_MIR_OSDAP2_ T015901_ T025302_316_002_1

42 SMOS L2 Ocean Salinity L1c software error flag T – T071906


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