Forest Height Estimation with X- Band InSAR: Phase Centre Location versus RVoG

Transcription

1 Forest Height Estimation with X- Band InSAR: Phase Centre Location versus RVoG Florian Kugler, Irena Hajnsek, Seung-Kuk Lee & Konstantinos Papathanassiou German Aerospace Center (DLR) Microwaves and Radar Institute (HR)

2 Lineout Test Sites: FinSAR Campaign INDREX II: Mawas Kobernausser Wald TempoSAR Campaign: Traunstein Biosar II Campaign: Krycklan Issues: Phase Centre Height Forest Height Extinction Comparision/Combination of different baselines 2

3 0 Height Validation X band vs L band boreal forest X band validated against Scatterometer Southern Finnland

4 INDREX-II: Mawas Test Site Peat swamp forest Forest Height: 15m 25m Biomass around t/ha Uniform structure Open canopy Flat Topography 4

5 Mawas X band Validation with Lidar Reference Height: Top Canopy height 100 (100 tallest tree per hectar) Lidar Strip was divided into 100 equal samples Inversion I using φ 0 from unvegetated area Lidar Strip Phase Center Height Inversion II using σ 0.3 d B/m (mean Extinction Inversion I) 5

6 Test Site Kobernausser Wald Kobernausser Wald: Upper Austria Temperate managed forest Hilly Topography Inhomogenous Composition Stands of different Heights from 4 to 35m and different age and different biomass Domintated by Coniferous trees Canopy mainly closed 6

7 Kobernausser Wald Dataset InSAR Coherence Amplitude Image Lidar Strip X Band Polarisation VV Single Pass Baseline :0.8m 7

8 Kobernausser Wald X band Validation with Lidar Inversion I using φ 0 from Lidar Inversion Heights Inversion Heights Lidar h100 Phase Center Reference Height: Top Canopy height h100 (100 tallest tree per hectar) Phase Center 8

9 Kobernausser Wald X band Extinction Estimation Stand: Mean Extinction from Inversion: 0.79dB/m Mean Extinction from Lidar h100: 0.82dB/m Mean Ground to Volume Ratio: 0.05 Mean forest Height, 25.7m 2dB/m Extinction from Lidar Inversion Extinction from height estimation 1dB/m 0dB/m 9

10 Traunstein Test Site Forest type Topography Height Species Biomass Temperate Moderate slopes 25 ~ 35m N. Spruce, E. Beech, White Fir 40 ~ 450 t/ha 10

11 Full Baseline Temposar data Half Baseline Coherence 0 to 1 Phase -π to π Coherence 0 to 1 Phase -π to π 11

12 Estimated Forest Heights Full Baseline Inversion using external ground phase Tends to underestimate high forests Scattering Centre clearly below estimated forest height 40m Inversion height Scattering Centre 20m 0m 12

13 Estimated Forest Heights Half Baseline Inversion using external ground phase Tends to underestimate high forests Scattering Centre clearly below estimated forest height Good Inversion Performance in near range 40m Inversion height Scattering Centre 20m 0m 13

14 Estimated Extinction Full Baseline Half Baseline Estimated from Height Inversion Estimated from Height Inversion Estimated with Reference Height Estimated with Reference Height 14

15 Lidar Tree Vegetation height 40m 20m 15

16 Biosar II Test Site Krycklan Sweden Krycklan forest: Location: middle Sweden boreal forest high topography Composition stands of different Height maximum forest height: ~ 30m mean forest height: 17m stands of different age and different biomass domintated by Coniferous trees 16

17 Full Baseline Biosar data Half Baseline Coherence 0 to 1 Phase -π to π Coherence 0 to 1 Phase -π to π 17

18 Biosar dual Baseline Inversion results Extinction Forest Height 2dB/m 40m 1dB/m 20m 0dB/m 0m 18

19 Summary Forest Height Inversion using X-Band Forest height estimation using X band provides prommissing results for tropical as well as for temperate & boreal forest conditiions X band Phase Center is significantly lower than Pol-InSAR forest height Especially in less dense forest conditions as can be found in boreal forests X band could provide good results Limitting factor for X band is forest density If there is an external DEM available we can go even further The results show a high potential of TanDEMX for forest height estimation in certain ecosystems, even if Quad or Dual Pol data are available 19