1 / 42

Soil moisture retrieval from space a review?

Soil moisture retrieval from space a review?. Claire Gruhier, Silvia Juglea, Patricia deRosnay and Yann Kerr. Atmosphere Control (Radiation). Surface Control (Freeze/Thaw). Surface Control (Soil Moisture). Main factors controlling the water, energy and carbon fluxes.

brian
Download Presentation

Soil moisture retrieval from space a review?

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. Soil moisture retrieval from spacea review? Claire Gruhier, Silvia Juglea, Patricia deRosnay and Yann Kerr GEWEX May June 2007 Land Surface Flux Workshop

  2. Atmosphere Control (Radiation) Surface Control (Freeze/Thaw) Surface Control (Soil Moisture) Main factors controlling the water, energy and carbon fluxes Churkina & Running, 1998 GEWEX May June 2007 Land Surface Flux Workshop

  3. What is Soil moisture? • Water in • the first mm • The first centimeters • In the litter layer • The root zone (Vadose) • The water table • The total • The total including interception • Antecedent precipitaion index • An adjusting variable allowing models to run and to give ET • A soil wetness index • A red coulour in GRACE gravity fields • Does it exist? • etc GEWEX May June 2007 Land Surface Flux Workshop

  4. Laboratory Oven-drying soil samples samples analysis chemical methods In situ neutron probes resistivity Capacity probes Remote sensing SW SWIR IR passive and active microwaves  Remote sensing using microwaves opens a way towards surface soil moisture mapping Measuring soil moisture GEWEX May June 2007 Land Surface Flux Workshop

  5. ESTIMATION DE L’HUMIDITE DU SOL PAR TELEDETECTION RADAR Soil Moisture Remote Sensing ??? GEWEX May June 2007 Land Surface Flux Workshop P. de Rosnay, F. Baup, E. Mougin, C. Gruhier, F. Timouk, P. Hiernaux, I. Chenerie,Y. Kerr

  6. Probing depth? Local calibration: GEWEX May June 2007 Land Surface Flux Workshop

  7. Field measurements: Soil moisture dynamics surf Ebangui Mallam soil moisture vertical profile before after rain: P= 61mm DW=51mm 2.5m 0 SM %m3/m3 12 Agoufou SM dynamics at different depths GEWEX May June 2007 Land Surface Flux Workshop

  8. Field measurements for upscaling purpose: Transect measurements -> kilometric to 50km scale information Surface Soil Moisture (SSM) - 1km transects: every 10 m. - 50km: every 1km Total ~60 transect measurements for 2004-2006 Relationship between: local (station) & kilometric (transects) surface soil moisture -> kilometric calibration of SSM GEWEX May June 2007 Land Surface Flux Workshop

  9. Influence of Ws & roughnessActive microwaves (radar) s =1, 0.8, 0.6, 0.4 cm Ws=30, 25, 20, 15 % P. Waldteufel 1999 GEWEX May June 2007 Land Surface Flux Workshop

  10. 1 - En Actif: ENVISAT/ASAR MALI (Agoufou): Baup et al 2007a et 2007b Précision d’inversion: 2.8% et 2.2% sur les 2 sites Résol: ~ 1km, 15j Niger (Kori de Diantandou): (Zribi et al 2006) GEWEX May June 2007 Land Surface Flux Workshop

  11. Active Microwave Remote Sensing: ENVISAT/ASAR - Methodological development and validation over Agoufou intensive site - Use of WS mode, HH polarization - Normalization function accounts for vegetation angular effect: - Dry season (Nov-May) - Wet season (Jun-Oct) GEWEX May June 2007 Land Surface Flux Workshop Baup et al. RSE 2006 (submitted)

  12. Inter-annual variations of backscatter (ERS-WSC) in the Sahelian area Jarlan et al. GEWEX May June 2007 Land Surface Flux Workshop

  13. ERS-WSC / NDVI VGT Comparison in Sahel Jarlan et al. GEWEX May June 2007 Land Surface Flux Workshop

  14. Galactic TEC O2, IWC, T, ILWC, rain, and resp heights Tv, w, WC, structure,S s,Ts,S/C,r, SM GEWEX May June 2007 Land Surface Flux Workshop

  15. TB sensitivity Kerr, 1997 GEWEX May June 2007 Land Surface Flux Workshop

  16. Influence ofWVon radiometric sensitivity to Ws • In order to penetrate vegetation cover, lowest possible frequencies should be selected. • F < 1GHz : large Faraday effects • Then the protected frequency is : 1.41 GHz ! Kerr and Jackson, 1995 GEWEX May June 2007 Land Surface Flux Workshop

  17. Jackson 2001 GEWEX May June 2007 Land Surface Flux Workshop

  18. Retrievals Wigneron et al., 95 GEWEX May June 2007 Land Surface Flux Workshop

  19. Passive Microwave Remote Sensing Inversion of AMSR Brightness temperature Statistical inversion based on multiple configuration observation of the surface, provided by AMSR polarization H and V. SM* = a0 + a1 PR +a2 (TBv-TBh) ; SM* retrieved Surface Soil Moisture PR = (Tbv-TBh)/(TBv+TBh) ; Polarization ratio from AMSR BT measurements Cost function based on minimization of RMSE Validation of correlation, RMSE, Efficiency, Mean Bias Range -1 to 1 (Best agreement) On going: investigate further statistical inversion (multi freq C & X bands) and addresse semi-empirical regression based on C-band modeling GEWEX May June 2007 Land Surface Flux Workshop

  20. Passive Microwave Remote Sensing: AMSR AMSR on Gourma Supersite : NASA products overestimate SSM Specific SSM inversion is developed based in statistical regression of bi-polarized measurements. Validation preliminary results: RMSE(%m3/m3) Correlation Efficiency MeanBias (%m3/m3) 2006 2005 AMSR-NASA 4.32 0.54 -0.8 3.3 5.04 0.45 -0.37 3.25 AMSR-retrieved 2.77 0.5 0.25 0.01 3.8 0.46 0.21 -0.03 -> Statistical retrieval slightly improves the accuray of AMSR SSM compared to NASA products – Further investigations required to take advantage of multispectral (C & X bands) GEWEX May June 2007 Land Surface Flux Workshop

  21. SMOSREX and Sud-Ouest France, Toulouse Comparison between AMSR-E and surface soil moisture over 3 networks for 2005 GEWEX May June 2007 Land Surface Flux Workshop

  22. GoREx (NAFE) Autralia, Goulburn River catchment Comparison between AMSR-E and surface soil moisture over 3 networks for 2005 GEWEX May June 2007 Land Surface Flux Workshop

  23. AMMA – Gourma region Mali, Agoufou Comparison between AMSR-E and surface soil moisture over 3 networks for 2005 GEWEX May June 2007 Land Surface Flux Workshop

  24. Passive Microwave Remote Sensing: AMSR July 3nd decade Aug 1st decade Aug 2nd decade AMSR-E Land 3 NASA products (Njoku et al 2003): Soil Moisture : -> 1) Evaluation with ground soil moisture network and upscaling measurements Radiometric measurements (Brightness temperatures): -> 2) Development of statistical inversion over the Gourma super site GEWEX May June 2007 Land Surface Flux Workshop

  25. EVOLUTION OF MEAN SOIL MOISTURE FOR JANUARY (SMMR + AMSR) SMMR AMSR FOR JULY SM X10 YEAR GEWEX May June 2007 Land Surface Flux Workshop

  26. EVOLUTION OF SOIL MOISTURE FOR JULY SMMR (regression AMSR) GEWEX May June 2007 Land Surface Flux Workshop

  27. Issues • Topography • Mixed pixels • Sub pixel heterogeneity • Saturations (water, forests, snow?) • Root Zone Soil moisture, • Freezing • litter • A word about forests • ... GEWEX May June 2007 Land Surface Flux Workshop

  28. COUPLING INTERACTIVE VEGETATION MODEL (ISBA-AGS) and RT MODELS Wigneron et al., 2001 GEWEX May June 2007 Land Surface Flux Workshop

  29. Wigneron et al 2000 GEWEX May June 2007 Land Surface Flux Workshop

  30. Wg mean, W mean t + dt Coupling and disaggregation Scheme LE, Rn,H,G percolation Saturation excess Runoff Wg mean, W mean t Infiltration Subsurface flow TOPMODEL SVATSIMPLE DTM + { Wg i }, { W i } t + dt Soil proprieties Pellenq et al., 2001 GEWEX May June 2007 Land Surface Flux Workshop

  31. Spatialised Disaggregation Results DOY 610 SIMULATED TOPOGRAPHY + SOIL DEPTH SIMULATED TOPOGRAPHY OBSERVED Correlation: Pellenq et al., 2001 R2=0.88 R2=0.895 GEWEX May June 2007 Land Surface Flux Workshop

  32. NIGER: Meso scale TB simulations: ISBA + C-MEB (1km²)C-band Microwave Emission of the Biosphere (Pellarin et al., 2007, in prep)Agrégation/désagrégation Simulated TB 1km 55km footprint 55km AMSR-E TB Level 3 25km product Résol ~ 25km/1j-> désagrégation à 1km/1j Simulated TB 1km Simulated TB 25km-reggrided GEWEX May June 2007 Land Surface Flux Workshop

  33. Use of Altimetry • Principle • Measure water heights wit use of alytimeters, • Gives amount of water • Issues • Requires width and shape of bottom • Validity of water masks • Small bodies wrt resolution GEWEX May June 2007 Land Surface Flux Workshop

  34. Water fractions and ESRI GEWEX May June 2007 Land Surface Flux Workshop

  35. Use of gravimetry • Principle • Measures changes of gravimetric field • Gives changes in water stocks • Issues • A signal is there but • Never validated • Strange results not yet explained GEWEX May June 2007 Land Surface Flux Workshop

  36. Seasonal changes in gravity as seen by GRACE (truncated at n = 10) and predicted from a mean hydrology model (from Andersen et al. 2005a), unit of the amplitude is μGal (= 10-8 m s-2) unit of the phase is days wrt January first. GEWEX May June 2007 Land Surface Flux Workshop

  37. Standard deviation (in μGal) of the annual changes from 5 different hydrology models (from Andersen et al. 2005a). GEWEX May June 2007 Land Surface Flux Workshop

  38. Hydrological load (in mm of water equivalent) from the GLDAS model (left) and induced gravity changes (in μGal) (center) and ground vertical displacement (in mm) (right) for March and September 2003. GEWEX May June 2007 Land Surface Flux Workshop

  39. Differences for March and September 2003 of the gravity field (in m.s-2) between hydrological models and GRACE observations; upper left: raw LadWorld model corresponding at a truncation of degree n = 180 (1° x 1°); upper right same but truncated at n = 15 and lower center GRACE observations truncated at n = 15. GEWEX May June 2007 Land Surface Flux Workshop

  40. Other issues • Validation • Sea variations • Validation experiments • Antarctica • ….. GEWEX May June 2007 Land Surface Flux Workshop

  41. Conclusions? • Gravimetry • Needs validation • Active SAR • Relative values at best. • See scat • Active Scat • Very complementary • Freeze thaw • Altimetry • Complementary • Passive low freq • Needs aux data • Still some issues Why should P=ET+R+DS? GEWEX May June 2007 Land Surface Flux Workshop

  42. Thank you …..Any questions ? http//www.cesbio.ups-tlse.fr/us/indexsmos.html GEWEX May June 2007 Land Surface Flux Workshop

More Related