1 / 34

SMOS and Aquarius: SSS and Wind Effect

SMOS and Aquarius: SSS and Wind Effect. J. Boutin, X. Yin, N. Martin (LOCEAN, Paris), E. Dinnat (Chapman University/NASA/GSFC), S. Yueh (NASA/JPL) Coll. G. Reverdin (LOCEAN), G. Alory (LEGOS), F. Gaillard (LPO) ESA Expert Support Lab.(ARGANS, ICM, Ifremer, ACRI-st, CLS)

josiah
Download Presentation

SMOS and Aquarius: SSS and Wind Effect

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SMOS and Aquarius: SSS and Wind Effect J. Boutin, X. Yin, N. Martin (LOCEAN, Paris), E. Dinnat (Chapman University/NASA/GSFC), S. Yueh (NASA/JPL) Coll. G. Reverdin (LOCEAN), G. Alory (LEGOS), F. Gaillard (LPO) ESA Expert Support Lab.(ARGANS, ICM, Ifremer, ACRI-st, CLS) ESA/CNES SMOSCAL/VAL project (GLOSCAL) NASA ROSES project (Intercalibration of SMOS and Aquarius) QWG8, Boutin et al.

  2. Overview of this presentation • SMOS – Aquarius – ARGO maps • SMOS & Aquarius wind dependencies • Comparisons of SMOS SSS wrt in situ measurements (ship and ARGO) • Influence of using SSMI WS intead of ECMWF QWG8, Boutin et al.

  3. Data SATELLITE SSS -SMOS SSS reprocessed by ESA v5.5 (wind-model 1) Improvements with respect to previous versions: -Reduced coastal bias; OTT (systematic bias in the Field of View) every 2 weeks and separetely for ascending and descending orbits; improved wind correction ; improved RFI & outlier sorting SSS averages weighted by the variance of the error of the retrieved SSS (Boutin et al., TGRS, 2012), and restricted to wind speed between 3 and 12m/s USE ONLY ASCENDING ORBITS -AQUARIUS level 3 maps v1.2.3 IN SITU SSS -Optimal Interpolation of ARGO SSS: IFREMER In Situ Analysis System (ISAS) (Gaillard et al. 2009) -ARGO SSS (upper SSS between 10m and 0.5m depth) (CORIOLIS GDAAC) -Ships of Opportunity (Delayed mode data delivered by SSS observatory (http://www.legos.obs-mip.fr/observations/sss/)) QWG8, Boutin et al.

  4. Ascending vs Descending SSS: Sept 2011 SSS Ascending orbits SSS Descending orbits Descending OTTs not enough to remove stripes especially in September => Sun alias? Galactic noise? SSS error Ascending orbits SSS error Descending orbits QWG8, Boutin et al.

  5. SMOS - AQUARIUS – ARGO SSS – Sept-Dec 2011 Sept-Dec 2011 SMOS v5.5 (Ascending Orbits) Aquarius v1.2.3 ARGO OI QWG8, Boutin et al.

  6. Sept-Dec 2011 SMOS features: -issues close to land (image reconstruction) -Large RFI (N. Atl., Asian coasts) -Ice edge Aquarius features: -Underestimates in Southern Ocean -Overestimates close to islands (e.g. S. Pac ). SMOS & Aquarius features: -Better resolution of Amazone Plume -Lower SSS in rainy regions -Lower SSS in Indian Ocean SMOS-Aquarius -1 +1 SMOS-ARGO OI -1 +1 Aquarius-ARGO OI QWG8, Boutin et al. -1 +1

  7. SMOS & AQUARIUS WIND DEPENDENCIES Aquarius Tb-wind : -empirical wrt SSMI wind speed + NCEP wind direction (Yueh) -empirical wrt NCEP wind (Dinnat) SMOS Tb-wind : -Adjusted rough & foam models wrt SSMI wind speed (Yin et al, TGRS, 2012) -Adjusted rough & foam models wrt ECMWF wind speed (Yin et al, TGRS, 2012) -Empirical model wrt ECMWF wind speed (Tenerelli, 2011) -Empirical model wrt ECMWF wind speed (Guimbard et al, 2012) Given the uncertainty about the absolute bias between model and data (need for OTT correction for SMOS) all the curves have been adjusted at 7m/s QWG8, Boutin et al.

  8. Omnidirectional Tb-Wind dependencies Very similar SMOS and Aquarius Tb-Wind omnidirectional dependencies 3<WS<12 m/s Above 15m/s SMOS T higher than Aquarius T (especially in H polarization) 28.7° 37.8° 45.6° 7 7 7 Th (K) 0 0 0 2 17 2 17 2 17 WS (m/s) WS (m/s) WS (m/s) Aquarius (SSMI WS); Aquarius (NCEP WS); SMOS (SSMI WS); *,*,* SMOS (ECMWF WS) 7 7 7 Tv (K) QWG8, Boutin et al. 0 0 0 WS (m/s) 2 17 2 17 2 17 WS (m/s) WS (m/s)

  9. Tb dependency with Wind Direction 0 20 0 20 0 20 WS (m/s) WS (m/s) WS (m/s) Much larger dependency in Aquarius than in SMOS functions at high WS! 28.7° 37.8° 45.6° 0.9 0.6 0.3 0 0.9 0.6 0.3 0 0.9 0.6 0.3 0 V1 V2 H1 H2 T (K) SMOS and Aquarius Tb wind dependencies better agree for wind speed between 3 and 12m/s => confirm the relevance of SMOS L2 wind speed range flagging -0.3 -0.3 -0.3 Aquarius SMOS model 1 Tb=Tbwind + Tb1 cos(Phi) + Tb2 cos(2Phi) TbV1 TbV2TbH1TbH2 QWG8, Boutin et al.

  10. Comparisons of SMOS reprocessed SSS(v5) and in situ SSS • ARGO • Ship: • Indian Ocean (Lavender) • Atlantic Ocean: • Rio Blanco • Colibri and Toucan QWG8, Boutin et al.

  11. Comparisons with ARGO in selected regionsfar from land (Aug-Sept 2010 & 2011) 40 Atl subtrop SSSsmos Ind. S Pac S Pac trop N 32 40 32 SSSargo (SMOS SSS weighted averaged over 100km-10days around ARGO) SMOS – ARGO SSS in tropical Pacific 0.1 fresher than in other regions: rain? QWG8, Boutin et al.

  12. Indian Ocean: SMOS–Lavender Ship SSS19 Sep – 1 Oct 2010 Sept 2010 - SMOS SSS (Asc orbits) SMOS – ARGO OI SSS Next slides: SMOS SSS averaged over 10 days and 100km around Lavender time and location QWG8, Boutin et al.

  13. SSS latitudinal profiles – Ship-ARGO OI-SMOS Ship SMOS 10d-100km ARGO OI ARGO OI much smoother than Ship SSS: monthly & ~1 ARGO meas./10days, 2° SMOS (40km resolution) better sees small scale variability, but still some deficiencies (distance to coast? , RFI, islands…) On average: SSSARGO_OI-SSSTSG = 0.2 (0.23) SSSSMOS-SSSTSG = 0.0 (0.37) QWG8, Boutin et al.

  14. Atlantic Ocean SSS: SMOS and Rio Blanco Ship (Aug-Sep 2010) 50 Ship SMOS 10d-100km Latitude ITCZ -40 SSS 40 30 Distance to coast High noise close to land but qualitative agreementSMOS SSS fresher than ship in ITCZ QWG8, Boutin et al.

  15. Comparison of Toucan and Colibri ship and SMOS v5 reprocessed SSS Leslie David (master trainee), Gilles Reverdin, Jacqueline Boutin (LOCEAN) QWG8, Boutin et al.

  16. Toucan and Colibri Ship of Opportunity trajectories (2010-2011) SPURS region QWG8, Boutin et al.

  17. 18-22 October 2011 38 SSS ARGO interpolation SMOS Ascending 10days-100km Colibri Ship 32 5N 35N Latitude (°) QWG8, Boutin et al.

  18. QWG8, Boutin et al.

  19. Mean and std of difference (SMOS-Ship SSS) over the whole period 2010-2011and July-Aug-Sept 1 Std ~0.2-0.3 (except north of 25N in winter-Spring; RFIs?) 0.2 Bias and std(diff) -0.2 Coast/RFI Biases? Black /grey: all months Colors: July-Aug-Sept -1 10N 15N 20N Latitude 30N 35N QWG8, Boutin et al. (all sections except 19-Oct-2010, 11-Jul-2010 et 14-Mar-2011 )

  20. RFI sorting needs to be improved!! June 2011 38.5 35.5 34N 16N QWG8, Boutin et al.

  21. Conclusion SMOS SSS: • In tropical-subtropical regions, far from land, in non rainy region, precision at 100x100km2-10days ~0.3 • SMOS SSS freshening wrt in situ SSS (~5m depth) in rainy conditions: true salinity effect? Needs for surface drifters for validation (needs for a lot of matchups!!!) • Ship TSG: very useful for validating ‘small scale’ (<200km) variability (gradients) seen by SMOS • Still issues (sun aliases, land vicinity, ice edge, RFI sorting …): image reconstruction still in progress SMOS and Aquarius wind models • Tb-wind SMOS and Aquarius very similar: 3-12m/s but Aquarius lower above 12m/s; Aquarius azimuth dependency much larger at high wind speed QWG8, Boutin et al.

  22. Yin X.1, Boutin J.1, Martin N.1, Vergely J.2, Spurgeon P.3 1. LOCEAN/IPSL, UMR CNRS/UPMC/IRD/MNHN, France 2. ACRI-ST, France 3. ARGANS, United Kingdom Issues about wind speed uncertainties and SMOS retrieved SSS QWG8, Yin et al.

  23. Outline Impact of wind speed uncertainties on SMOS retrieved SSS 1) SSMI versus ECMWF wind speed 2) Difference in retrieved SSS using two different prior wind speeds 3) The eastern equatorial Pacific Ocean Conclusions and perspectives QWG8, Yin et al.

  24. Wind speed retrieved from SMOS data August 2010, ECWMF wind speed used as prior. WS (retrieved-prior) Incidence angle 40N 60 Eta Latitude 0 50S Distance to the track (km) -300 300 Distance to the track (km) In the centered swath (within +-300km), wind speed is adjusted with SMOS data; in the border of the swath (outside of +-300km), wind speed can not be adjusted with SMOS data (not enough incidence angles). QWG8, Yin et al.

  25. Data 1. SMOS Brightness temperature (last reprocessing: L1c v504) 1) August 2010, 436 ascending orbits over global ocean 2) September 2011, 418 ascending orbits over global ocean 2. ECMWF wind speed collocated with SSMI wind speed, August 2010 and September 2011 collocation radii of ±0.5 hour and ±50 km 3. SSS 1) SMOS SSS retrieved with ECWMF wind as prior. Roughness model fitted from ECMWF wind speed (Yin et al., TGRS SMOS special issue, 2012) is used. ( ESA reprocessing v550) 2) SMOS SSS retrieved with SSMI wind as prior, processed by LOCEAN. Roughness model fitted from SSMI wind speed (Yin et al., TGRS SMOS special issue, 2012) is used. 3) ARGO optimal interpolation (ISAS) (Gaillard et al. 2009) used as reference QWG8, Yin et al.

  26. One example of differences between ECMWF, SSMI and retrieved WS from SMOS data For the orbit 20100809T142544_20100809T151945, the ECMWF and SSMI wind speeds are quite different around 17S. QWG8, Yin et al.

  27. QWG8, Yin et al. 5 points running mean of SMOS TB TB simulations with ECMWF Wind TB simulations with SSMI Wind are closer to SMOS TB TB simulations with SSMI Wind No matter whether SSMI or ECWMF wind is used as prior, retrieved wind speed is closer to SSMI wind speed but still a little bit lower. _____ECMWF prior WS ---------SSMI prior WS • •Retrieved WS (ECMWF prior) • •Retrieved WS (SSMI prior) Latitude

  28. QWG8, Yin et al. SMOS SSSwith SSMI wind speed August 2010 monthly average SMOS SSS (+-300km) 3-12m/s (both ECWMF and SSMI) Similar spatial distribution The same for September 2011, not shown here. SMOS SSSwith ECMWF wind speed ARGO OI SSS

  29. QWG8, Yin et al. SMOS– ARGO OI SSS, SSMI prior wind speed 1 August 2010 monthly average SMOS SSS – ISAS/ARGO SSS 3-12m/s 1. In the eastern equatorial Pacific ocean, differences between SMOS SSS with SSMI WS and ARGO OI SSS are often lower than those with ECMWF WS. 2. In the eastern part of Pacific and Atlantic ocean, SSMI WS are lower than ECMWF WS. Also, the retrieved SSS with SSMI WS are lower than those with ECMWF WS. Similar patterns in September 2011, not shown here. -1 SMOS– ARGO OI SSS, ECMWF prior wind speed 1 -1 SMOS SSS(SSMI) – SMOS SSS (ECMWF) 1 -1 WS(SSMI) – WS (ECMWF) 1 -1

  30. QWG8, Yin et al. Retrieved WS(SSMI) Retrieved WS(ECMWF) -Monthly averaged August 2010- 1. In the eastern equatorial Pacific ocean, SSMI WS are much lower than ECMWF WS. 2. Retrieved WS with ECMWF WS are trying to get close to SSMI WS but not close enough. rWS(SSMI)- SSMI WS rWS(ECMWF)- ECMWF WS

  31. QWG8, Yin et al. Conclusions and Perspectives 1. In the centered part of the swath (within +-300km), wind speed is adjusted with SMOS data; In the border of the swath (outside of +-300km), wind speed can not be adjusted with SMOS data. 2. In the centered part of the swath (+-300km), the difference between SMOS SSS and ARGO OI SSS is lower than the border, since wind speed is corrected (partly) with SMOS data. 3. Locally (eastern equatorial Pacific), SSMI wind speeds used as prior in the retrieval perform better (SMOS retrieval scheme not able to completely correct for the differences between SSMI and ECMWF WS, but it decreases SSS bias locally). 4. Origin of differences in eastern equatorial Pacific? 5. Work in progress….

  32. QWG8, Yin et al. Sensitivity of L-band Tb (h- & v-pol) to θ, wind speed and SSS Tv/ WS >0 and with incidence angle Tv/ SSS<0 and abs() with incidence angle Th/ WS>0 and with incidence angle Th/ SSS<0 and abs() with incidence angle (at nadir, 20°C, Tb/ WS ~0.2K/m/s, Tb/ SSS~-0.5K/psu => a bias of 5m/s on WS  ~ a bias of -2psu on SSS) Incidence angle (°) Incidence angle Incidence angle From Dinnat et al. 2003

  33. SMOS SSS and WS retrieval method SMOS SSS (ESA level 2 retrieval) is retrieved through a least square minimisation of the difference between SMOS and modeled Tb. Retrieval of SSS (=100psu), SST (=1°C), WS(=1.5m/s on wind components) through the minimisation of: => estimate of SSS error (Levenberg & Marquard algorithm)

  34. QWG8, Yin et al. SSS v5 Descending August & September 2010 & 2011 August 2010 September2010 Descending OTTs not enough to remove stripes Larger stripes in September than in August => Sun alias? Galactic noise? Less outliers in the northern Atlantic in 2011 than in 2010Decrease of RFIs August 2011 September 2011

More Related