1. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 1 Nicolas Ackermann Supervisor: Prof. Christiane Schmullius Co-supervisors: Dr. Christian Thiel, Dr. Maurice Borgeaud DLR Oberpfaffenhofen, the 16th February 2011 Investigations of TerraSAR-X and Cosmo-SkyMed backscatter intensity and interferometric coherence over temperate forested areas TSX Science Team Meeting ENVILAND2 is sponsored by the Space Agency of the German Aerospace Center with federal funds of the German Federal Ministry of Economics and Technology on the basis of legislation by the German Parliament grant no. 50 EE 0844 - 50 EE 0847

2. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 2  Introduction  Test site & available data  Pre-processing & preliminary investigations  Analysis of the data  Conclusions Presentation outline

3. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 3  Context:  The monitoring of forested areas represents a great challenge in the context of the actual Global Warming.  The launch of TerraSAR-X spaceborne system in June 2007 has been pioneer of new capabilities for the retrieval of forest biophysical parameters.  Objectives:  Investigate the TSX and CSK backscattter intensity and interferometric coherence.  Underline the scattering and decorrelation mechanisms occuring in the temperate forest.  Provide some new scientific knowledge for future researches. Introduction

4. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 4 Test site & available data

5. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 5 Test site  Thuringia Forest (Germany)  Surface: 110 km x 50 km  Terrain variations  Tree species composition Scots pines Norway Spruce European Beech  Climate cool and rainy frequently clouded  Peculiarities logging for forest exploitation Kyrill storm (February 2007)

6. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 6 Test site Topography

7. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 7 Test site Forest understory

8. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 8  SAR data  ALOS PALSAR (L-Band, 46 days)  TerraSAR-X (X-Band, 11 days)  Cosmo-SkyMed (X-Band, 1 day)  Optical data  RapidEye  Kompsat-2  Ancillary data  Laser DEM 5 m  Laser points (2004),  Orthophotos (2008)  HyMap (2008,2009)  Forest inventory (1989-2009)  Photos with GPS coord. (2009)  Weather data  Field work 25 km Available data

9. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 9 Thuringia Forest test site (state February 2010) Sensor Radar- Frequency BeamPolarisation Incident angle # Scenes available TSXX-BandHSHH, VV21°-45°41 TSXX-BandSLHH, VV, HH/VV21°-45°9 TSXX-BandSMHH/HV, VV/VH21°-45°18 CSKX-BandHimageHH40°12 Satellite data 80 scenes

10. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 10 Pre-processing & preliminary investigations

11. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 11 Topographic normalisation  Relief TSX HS 23° HH Asc. 16jul09 Non normalised LiDAR DEM shaded relief 5 x 10 [km] High geometrical distorsions by steep incident angle.

12. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 12 Local incident angle Ground scattering area Topographic normalisation  Correction main components (Castel et al., 2001)

13. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 13 Topographic normalisation  Experiment - Polarplot Sensor heading : 350° Sensor azimuth angle : +90° 0° TSX SM 38° HH Asc. 21aug10 Normalised TSX SM 38° HH Asc. 21aug10 Non normalised Gamma nought [dB] Aspect [°] Slope oriented in radar flight direction High intensity for steep slopes facing radar.

14. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 14 Topographic normalisation TSX SM 38° HH Asc. 21aug10 Normalised Gamma nought [dB] Aspect [°] Overcorrection? Crown optical depth? Other effects?  Relief normalisation

15. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 15  Weather data  DWD: Deutsche Wetter Dienst  Acquisition period: 2006-2010  Parameters: Precipitation, Snowdepth, Water-equivalent, Wind, Temperature, Sunshine duration, relative Humidity  Pre-processing  Collaboration with FSU geoinformatic institute  JAMS (Jena Adaptable Modelling System) Software  2 temporal scales : daily / hourly Weather data [.xml ] Daily output generation Hourly Regionalised [.txt ] Daily [ raster ] Hourly Input conversion Daily input conversion Hourly Regionalisation Daily Selected [.dat ] Hourly Selected [.dat ] Daily Regionalisation Daily Regionalised [.txt ] Hourly output generation Hourly [ raster ] JAMS Software 90m Station 1 Station 2 Station 5 Station 3 Station 4 Weather data

16. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 16  Weather parameters outputs  Raster data  90m spatial resolution  Excel table  Describe mean weather values of the overlapping selected forest stands and satellite data Temperature [°C] Precipitations [mm] High: 36 0 Table weather data (simplified version) SensorAcquisition-date Daily (4 days meteorological conditions) Hourly (4 hours meteorological conditions) Beam T°air_mean [°C] T°air_mi n [°C] T°air_max [°C] Precipitation [mm] Humidity [%] Sunshine [hrs] Wind speed [m/s) T°air_mean [°C] Precipitation [mm] Humidity [%] Wind speed [m/s} TSX06/08/2009 17:09:13spot_074 5.73.19.120.381.72.13.92.92.893.94.7 TSX31/10/2009 05:25:57spot_069 7.64.611.516.776.42.14.05.12.088.44.4 …………………………………… TSX31/08/2009 05:34:23stripNear_009 10.94.516.70.169.89.63.3 11.40.075.33.8 Weather data Daily: 4 daysHourly: 4 hours Example Daily: 31mar08 - 03apr08 High: 10 0

17. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 17 Analysis of the data

18. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 18 Fields of investigations  Backscatter intensity  Multi-temporal  Polarisation  Frequency  Pass  Interferometric coherence  Visual interpretations  Stem volume

19. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 19 Precip [mm] Temp [°] Wind [m/s] Backscatter intensity  TerraSAR-X multi-temporal datasets Series of TSX HS, 34.4, HH, Asc. Acquisition dates Gamma nought [dB] Daily Good species separability over the acquisition time. Precipitations increase the backscatter.

20. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 20 Backscatter intensity Gamma nought [dB] – TSX SM HV. Gamma nought [dB] – TSX SM HH Gamma nought [dB] – TSX SM VV Gamma nought [dB] – TSX SM HH - 05may10 -- 22mar09 - Precip 2.3 [mm]Precip 1.3 [mm] HV do not allow tree species discrimination.  TerraSAR-X polarisation

21. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 21 Backscatter intensity  TerraSAR-X Frequency Gamma nought [dB] – FBD 34° HH Asc. Gamma nought [dB] – TSX SM 33° HH Asc. - 16jun10 - - 27jun10 - A ratio X-band / L-band improves the separation between Norway Spruce and European Beech. TSX (X-band) Precip daily: 0.8 [mm] Precip hourly: 0.0 [mm] PALSAR (L-band) Precip daily: 1.1 [mm] Precip hourly: 0.0 [mm]

22. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 22 Backscatter intensity  TerraSAR-X pass direction Gamma nought [dB] – TSX HS HH 46° Desc. Gamma nought [dB] – TSX HS HH 48° Asc. (mon - 28aug09 - - 26aug09 - Dew effect is not clearly observable. Intensities differ due to the varying penetration in Ascending and Descending. Descending: 6 a.m (morning) Precip daily: 1.1 [mm] Precip hourly: 0.0 [mm] Ascending: 6 p.m (afternoon) Precip daily: 1.7 [mm] Precip hourly: 0.0 [mm]

23. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 23  Coherence  The degree of coherence can be related to several factors, each expressing a specific source of decorrelation. Interferometric coherence The temporal decorrelation is related to the stability of the objects between the two acquisitions. The volume decorrelation is related to objects presenting a vertical extension. This factor is spatial baseline dependent.

24. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 24 Interferometric coherence  Visual interpretations RapidEye RGB – 13jun09 TSX HS 28may10 - 08jun10 CSK Himage 28sep10 - 29sep10 - 1 day temporal baseline - - 11 days temporal baseline -

25. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 25 Interferometric coherence  TerraSAR-X coherence vs Stem volume Coherence – TSX HS HH 37° Asc. Stem volume [m 3 /ha] - 06oct09 – 17oct09 - r 2 S =0.01 r 2 B =0.01 As expected, no correlation between stem volume and TSX coherence.

26. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 26 Interferometric coherence  Cosmo-SkyMed coherence versus Stem volume r 2 S = 0.15 r 2 B =0.02 r 2 P =0.06 r 2 S =0.00 r 2 B =0.01 r 2 P =0.01 r 2 S =0.01 r 2 B =0.01 r 2 P =0.01 r 2 S =0.03 r 2 B =0.01 r 2 P =0.00 r 2 S =0.05 r 2 B =0.00 r 2 P =0.01 r 2 B =0.01 r 2 S =0.11 Perpendicular baseline Interferometric coherence Stem volume [m 3 /ha] r 2 P =0.01 Increase of correlation with higher perpendicular baseline. 1 day temporal baseline

27. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 27 Interferometric coherence  Cosmo-SkyMed coherence - Weather information Weather data for Cosmo-SkyMed acquisitions Not yet available

28. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 28 Conclusions and outlook

29. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 29 Conclusions and outlook  Different investigations of the TSX and CSK backscattter intensity and interferometric coherence have been conducted.  Conclusions and open issues  The topography influence is not fully understood.  The signal for Norway Spruce and European beech can be separated with TSX HH or VV.  Weather conditions and particularly precipitations affect the backscatter intensity and interferometric coherence.  Interferometric coherence in X-band with 1 day temporal baseline may show a potential for estimating biomass.  Future work  Further investigations for the topographic normalisation  Analysis of ALOS PALSAR intensity and interferometric coherence  Derivation of indices and ratios between X-band and L-band

30. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 30 I would like to thank DLR, ESA, ASI and RESA for the distribution of the data ENVILAND2 is sponsored by the Space Agency of the German Aerospace Center with federal funds of the German Federal Ministry of Economics and Technology on the basis of legislation by the German Parliament grant no. 50 EE 0844 - 50 EE 0847 Acknowledgements

31. N. Ackermann - Investigations of TSX and CSK backscatter intensity and interferometric coherence over temperate forested areas - 31 Thuringia Forest – July 2010 Questions ? Vielen Dank für Ihre Aufmerksamkeit!