1) Pol-InSAR techniques have been demonstrated to accurately estimate forest height at P-band wavelengths over different forest types and terrains using airborne data. Forest height was retrieved to within 1.9-6m (10-30% error) compared to lidar measurements. 2) Transitioning the techniques for use on a spaceborne mission like BIOMASS presents challenges related to decreased spatial resolution, limited baseline configurations, and increased temporal decorrelation. 3) Modeling suggests the spaceborne system could achieve 20-40% accuracy in forest height estimation over heights ranging from 10-60m, but performance may decrease over sloped terrain or heterogeneous forests.

1. Potential & Challenges of Pol-InSAR Techniques for Forest Height Estimation in the context of the BIOMASS Mission S-K. Lee, S. Sauer, F. Kugler, R. Scheiber, I. Hajnsek & K. Papathanassiou German Aerospace Center (DLR) Microwaves and Radar Institute (DLR-HR)

2. Motivation 26 Plots / 27m x 32m / l a = 0.6 Sungai Wain Lowland Dipterocarp Forest Mawas 1 Riverine Peat Swamp Forest Mawas 2 Tropical Peat Swamp Forest 20 Plots / 10m x 10m / l a = 0.5 20 Plots / 10m x 10m / l a = 0.6 Insufficient Number of samples !!! - But clear trend visible !!!

3. Volume Coherence … vertical reflectivity function Interferometric Coherence Volume Coherence Vertical Wavenumber: G/V Ratio: Volume Height Extinction Topography G/V Ratio 2 Layer Scattering Model

4. The Effect of the Ground-2-Volume Component Phase Center Location as a Function of Polarisation / Ground Variance of the Phase Center Location due to Volume, System and Temporal Decorrelation Ground and Volume No Ground Only Volume Volume only

5. Campaigns Summary Lidar 4 - 6m / .5 -.7 30º-45º Flat Multiple >2 15min Managed Semi Boreal BIOSAR-I Lidar 4.5m / .65 30º-50º Hilly Multiple >2 15min Boreal BIOSAR-II Lidar 1.9m / .95 30°-45° Locally Slopes Multiple >2 15 min Temperate TempoSAR Stand < 2m 30°-40° Flat 1 15 min Managed Temperate Nezer Forest Lidar 2.m / .94 35º-40º Flat 3 20min Peat Swamp INDREX-II Stands 2-3m 40º Hilly 2 20min (Lowland) Dipterocarp INDREX-II 30-40º Incidence Angle 2,5m (Preliminary) Results RMS / ρ2 15 min + … Temporal Baseline Stand Hilly 1 Tropical TropiSAR Terrain Forest Campaign Reference Spatial Baselines

6. Ground-2-Volume Ratios Range INDREX-II: 1402; Mawas INDREX-II: 0601; Sungai Wain m max m min

7. Ground-2-Volume Ratios Range BioSAR 2007: 0401; Remningstorp m max m min BioSAR 2008: 0103; Krycklan

8. Model Miss-Match of Vertical Structure Function (f(z)) P-band P-band 50 40 30 20 10 0 m MAWAS Krycklan Forest Height Forest Height LIDAR H100 (m) LIDAR H100 (m)

9. Effect of Extinction and Ground-to-Volume Ratio σ > 0 m 3 = 0 σ > 0 m 3 ≠ 0 σ >< 0 m 3 = 0 σ >< 0 m 3 ≠ 0

10. Campaigns Summary Temporal Deco 2 Layer Model with Temporal Decorrelation Extinction Volume Coherence Volume Height Topography G/V Ratio Temp. Deco. Volume Temp. Deco. Ground 1-7d 2 / 4 / 7 / 14 / 20 / 22d 1 - 15d 1 / 30 / 56d 20min Temporal Baseline 0.94 / 0.85 / 0.90 / 0.80 / 0.92 / 0.90 Tropical TropiSAR 0.95 - 0.95 Managed Temperate TempoSAR Tropical Managed Semi Boreal Peat Swamp Forest La Selva BIOSAR-I INDREX-II Campaign Lidar Lidar Comments 0.6-0.8 0.95 / 0.9 / 0.85 0.93 Temporal Decorrelation 10m 20m 30m

11. Campaigns Summary Temporal Deco with Volume Coherence & Decorrelation 1-7d 2 / 4 / 7 / 14 / 20 / 22d 1 - 15d 1 / 30 / 56d 20min Temporal Baseline 0.94 / 0.85 / 0.90 / 0.80 / 0.92 / 0.90 Tropical TropiSAR 0.95 - 0.95 Managed Temperate TempoSAR Tropical Managed Semi Boreal Peat Swamp Forest La Selva BIOSAR-I INDREX-II Campaign Lidar Lidar Comments 0.6-0.8 0.95 / 0.9 / 0.85 0.93 Temporal Decorrelation 10m 20m 30m

13. Decorrelation Modeling Phase Screens Phase & Amplitude Deco

14. Deterioration of Resolution (P-band BIOSAR) Original airborne resolution (2m x 5m Multilook) Degraded resolution (50m x 50m Multilook)

15. BIOSAR-I: Interferometric Coherence History 100MHz 6MHz HH Channel 6MHz + NESZ + Ambiguities T-deco = 0.9 Coheren c e 6MHz Coheren c e 100MHz

16. BIOSAR-I: Interferometric Coherence History 100MHz 6MHz HH Channel 6MHz + NESZ + Ambiguities T-deco = 0.9

17. Mawas Test Site / INDREX-II Remningstorp Test Site Kryckland Test Site Mawas Test Site HV Amplitude 100MHz 6MHz HV Amplitude 100MHz 6MHz HV Amplitude 100MHz 6MHz

18. BIOSAR-I: Single & Dual Baseline Inversion of Forest Height Single baseline inversion; Original data (100MHz) i Single baseline inversion; Spaceborne scenario (6MHz) i Single baseline inversion; Spaceborne scenario + T-deco Dual baseline inversion; Spaceborne scenario + T-deco

21. Potential & Challenges of Pol-InSAR Techniques for Forest Height Estimation in the context of the BIOMASS Mission S-K. Lee, S. Sauer, F. Kugler, R. Scheiber, I. Hajnsek & K. Papathanassiou German Aerospace Center (DLR) Microwaves and Radar Institute (DLR-HR)