The document presents a study on retrieving soil moisture under vegetation using dual polarized ALOS PALSAR data. Field measurements were taken at a test site to measure soil properties and vegetation characteristics. PALSAR data from multiple dates was processed to generate HH, HV backscatter and alpha, entropy, and span images. A grassland soil moisture retrieval model was developed that accounts for effects of the grass canopy and thatch layer on the radar signal. The model was able to estimate high resolution surface soil moisture patterns and distributions without using prior vegetation information.

1. Soil Moisture Retrieval Under Vegetation Using Dual Polarized PALSAR DataChristian Koyama & Karl SchneiderDepartment of GeosciencesUniversity of CologneIGARSS 2011 VancouverJuly 26, 2011

2. OutlineTest Site & Field Measurements

3. ALOS PALSAR Data & Processing

4. Grassland Soil Moisture Retrieval Model

5. High Resolution Surface Soil Moisture Patterns

6. ConclusionsTable of Contents- 02 -

7. Grass layerLayer depth: 5 – 175 cmDielectric constant: 15 – 25 Blade density: 1000 – 3000/m²Grass biomass: 0.2 – 3.1 kg/m²Thatch layerLayer depth: 2 – 4 cmDielectric constant: 6 – 70Soil half spaceDielectric constant: 9.7 – 33.8Texture: clay/silt loamGround Truth Data(test site and field measurements)- 03 -

8. PALSAR Fine Mode Dual Polarization DataRegion: Track 647+648 / Frame 1000+1010Ground Range Resolution: 15 mCenter Frequency: L-band @ 1,270 MHzChirp Bandwidth: 14 MHzPolarization: HH + HVOff-Nadir Angle: 34.3 deg.8/2/20079/17/20075/4/20086/2/20086/19/20087/18/20086/22/20097/21/20099/5/20099/22/20095/10/20106/25/201010/21/2009Track 647Track 648Soil moistureSurface roughnessBiomassJan.Feb.Mar.Apr.MayJuneJulyAug.Sep.Oct.Nov.Dec.Aug.Sep.Oct.Nov.Dec.Jan.Feb.Mar.Apr.MayJuneJulyAug.Sep.Oct.Nov.Dec.Jan.Feb.Mar.Apr.MayJune2010200720082009ALOS PALSAR FBD343 DATA(product description & acquisition overview)- 04 -

9. ALOS PALSAR FBD343 Level 1.1Multi-looking[C2] Matrix Elements ProcessingHH Power Imageσ0HHHV Power Imageσ0HVMulti-LookingCovariance [C2] Matrix ElementsCoregistration + Generic FilteringHAalphaspanTerrain GeocodingH/A/Alpha DecompositionRadiometric CalibrationGeocodingSimplified Processing Chain(basicprocessingand polarimetric decompositionof FBD343)- 05 -

10. 2008-06-022008-07-182009-07-212004000MetersChristian N. KoyamaUniversity of CologneIGARSS 2011Vancouver, July 26Dual-pol α/H/span-HSV(H = alpha / S = entropy / V = span)

11. Grass canopyThatchMatrix soilThatch Layer Effect- 7 -

12. 2009-07-212008-05-042007-09-172008-06-02mv = 51.1 SD = 4.2mv = 34.5 SD = 3.4mv = 48.7 SD = 4.9mv = 37.9 SD = 4.4Alpha [deg.]Alpha [deg.]Alpha [deg.]Alpha [deg.]EntropyEntropyEntropyEntropyCloude, S.R. (2007): “The Dual Polarisation Entropy/Alpha Decomposition: A PALSAR Case Study, “ In Proceedings of PolInSAR 2007.Grassland H2αPlanes- 8 -

13. Empirical Grassland Parameter Model- 9 -

14. Grassland Soil Moisture Estimation- 10 -

15. 2007-08-022007-09-17Christian N. KoyamaUniversity of CologneIGARSS 2011Vancouver, July 262575Surface Soil Moisture Distributionmv [Vol.-%]

16. ConclusionsL-band dual-pol SAR has the potential to correct for disturbing effects occurring in grassland ecosystems without the use of a priori knowledge

17. The retrieval algorithm is suitable to account for varying effects of vegetation and thatch

18. The thatch layer is the major source of attenuation

19. At L-band the amount of above ground grass biomass and its geometric properties can be neglected if <2 kg/m²Conclusions- 12 -

20. Thank you for your attention.Acknowledgements The authors thank the Japan Aerospace Exploration Agency (JAXA) and the European Space Agency (ESA) for the provision of ALOS PALSAR data through their PI programme (AOALO.3570). Financial support by the SFB/TR32 "Patterns in Soil-Vegetation-Atmosphere Systems" funded by the German Research Foundation (DFG) is gratefully acknowledged. christian.koyama@uni-koeln.dewww.tr32.de- 13 -

21. 2009-07-212009-07-212009-07-212004000MetersChristian N. KoyamaUniversity of CologneIGARSS 2011Vancouver, July 26Dual-pol Pauli-RGB(R = C22 /G = C11-2xC12r+C22 /B = C11)

22. 2008-05-042008-06-022008-06-19Christian N. KoyamaUniversity of CologneIGARSS 2011Vancouver, July 262575Surface Soil Moisture Distributionmv [Vol.-%]

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