Biomass Estimation from Forest Vertical Structure: Potentials and - - PowerPoint PPT Presentation

Microwaves and Radar Institute / Pol - InSAR Research Group

Biomass Estimation from Forest Vertical Structure: Potentials and Challenges for Multi-Baseline Pol-InSAR Techniques

• M. Pardini, F. Kugler, S.-K. Lee, S. Sauer, A. Toraño Caicoya & K. Papathanassiou

Microwaves and Radar Institute (DLR-HR) German Aerospace Center (DLR)

Microwaves and Radar Institute > 30.05.2006

Microwaves and Radar Institute

Ocean Currents* Soil Moisture* Sea Ice Extent* Forest Biomasse Change* Deforestation, Degradation, Fires* (REDD) Glacier & Ice Cap Dynamics* *) Essential Climate Variables Volcanic Activities Earthquakes Permafrost* Land Slides Flooding Biodiversity

Microwaves and Radar Institute > 30.05.2006

Microwaves and Radar Institute

Science Product Coverage Product Resolution Product Accuracy Biosphere Forest Height All forest Areas (Height ≥ 8 m) 50 m (global) 20 m (local) ~ 10 % Above Ground Biomass 100 m (global) ≤ 50 m (regional) ~ 20 % (or 20 t/ha) Vertical Forest Structure 50 m (global) 20 m (local) 3 layers Underlying Topography 50 m < 4 m Geo-/Lithosphere Plate Tectonics all risk areas 100 m (global) < 20 m (fault) 1 mm/year (after 5 y) Volcanoes all land volcanoes 20 – 50 m 5 mm/week Landslides risk areas 5 – 20 m 5 mm/week Subsidence urban areas 5 – 20 m 1 mm/year Cryo- & Hydrosphere Glacier Flow main glaciers 100 – 500 m 5 – 50 m/year Soil Moisture selected areas 50 m 5 – 10 % Water Level Change regional 50 m 10 cm Snow Water Equivalent local (exp.) 100 – 500 m 10 – 20 % Ice Structure Changes local (exp.) 100 m > 1 layer Ocean Currents

• prio. areas

~ 100 m < 1 m/s All Digital Terrain & Surface Model global ~ 20 m (bare) ~ 50 m (forest) 2 m (bare) 4 m (veg.)

Microwaves and Radar Institute > 30.05.2006

Microwaves and Radar Institute

Overview

Biomass estimation: from “height to biomass allometry” to “structure to biomass allometry” Vertical structure estimation from multi-baseline Pol-InSAR data Spectral estimation Polarization coherence tomography Real data experiments with airborne acquisitions (test site over the Traunstein forest) Can “radar” structure express biomass? A preliminary validation Conclusions

Microwaves and Radar Institute > 30.05.2006

Microwaves and Radar Institute

Height to Biomass Allometry

Ebersberger Forst Intensely managed Single species (Spruce) Height Range (H100): 5 - 40m Biomass Range: 40 ~ 350 t/ha Flat Terrain Bürgerwald Traunstein “Close to Nature” Temperate managed forest

• N. Spruce, E. Beech, White Fir

Height Range (H100): 10 - 40m Biomass Range: 40 ~ 450 t/ha Moderate Slopes Nationalpark Bayrischer Wald Natural development since 1972

Montane spruce forest > 1100m asl. Submontane mixed forest Floodplain spruce forest < 600m asl

Height Range (H100): 5 - 45m Biomass Range: 40 ~ 450 t/ha Steep Slopes

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Microwaves and Radar Institute

Height to Biomass Allometry

50 . 1

H 66

.

1 la B * =

Ebersberger Forst Bürgerwald Traunstein Nationalpark Bayrischer Wald

Microwaves and Radar Institute > 30.05.2006

Microwaves and Radar Institute

Structure to Biomass Allometry

Ebersberger Forst Bürgerwald Traunstein Nationalpark Bayrischer Wald a1 a2 a3



= =



*

=

H i 3 1 j j j P

a 11 . 3 B *

i

(z )

Microwaves and Radar Institute > 30.05.2006

Microwaves and Radar Institute VU 8 > Autor Name

2 1

S S

      

* * * 2 2 1 1 2 1 2 1

S S S S S S ) S S ( γ ~

Interferometric Coherence

Temporal

γ ~

… temporal decorrelation … additive noise decorrelation

SNR

γ

Volume

γ ~

Volume SNR Temporal

γ ~ γ γ ~ γ ~ 

… geometric decorrelation

SAR Interferometry for Volume Structure

Volume Coherence

 



v v z

• z

h

• h
• z

ik z ik Vol

dz ) z ( f dz e ) z ( f e )) z ( f ( γ ~ ) z ( f ) z ( f … vertical reflectivity function Vertical Wavenumber: ) θ sin( θ Δ κ κ

z 

Baseline diversity allows to sample the same vertical structure spectrum at different spatial frequencies

Microwaves and Radar Institute > 30.05.2006

Microwaves and Radar Institute

Vertical structure estimation as a spectral estimation problem

Normal-to-slant range height Equivalent cross-track array

S1 S2 S3 SK

Classic beamforming (Fourier-based) Adaptive beamforming (Capon-based): high resolution, low sidelobes, but radiometrically non linear Covariance matrix brings all the information Need for an adequate number of baselines Baseline distribution and total baseline length play a primary role

g (z1) g (z2) g (zM) f (z1) f (z2) f (zM)

Multi-baseline data vector

S

S

Elevation steering (tuning)

f (z)

Data-dependent Interference rejection Sweeped variable structure bandpass (variable beamshape)

Microwaves and Radar Institute > 30.05.2006

Microwaves and Radar Institute

S1 S2 S3 SK

Polarization Coherence Tomography

Volume Coherence

 



v v z

• z

h

• h
• z

ik z ik Vol

dz ) z ( f dz e ) z ( f e )) z ( f ( γ ~ ) z ( f … vertical reflectivity function ) θ sin( θ Δ κ κ

z 

) z ( f Vertical Wavenumber:

 



v v z

• z

h

• h
• z

ik z ik Vol

dz ) z ( f dz e ) z ( f e )) z ( f ( γ ~

 



 

1 1 ' z 2 h k i 2 h k i v h z ik

' dz e )) ' z ( f 1 ( e 2 h dz e ) z ( f

v z v z v z

) ' z ( P a ) ' z ( f

n n n









 

1 1 n n

' dz ) ' z ( P ) ' z ( f 2 1 n 2 a

 



 

1 1 v h

' dz )) ' z ( f 1 ( 2 h dz ) z ( f

v

Fourier Legendre Series: where

) z ( f

Microwaves and Radar Institute > 30.05.2006

Microwaves and Radar Institute

The Traunstein dataset

LIDAR DTM LIDAR forest height

570 m 775 m 0 m 50 m Slant range Slant range

HV Amplitude Image

Slant range 0 m 50 m

Vertical resolution 2 / max(kz)

Slant range

Frequency L-band (1.3 GHz) Baselines 0,5,10,15, 20 nom. Full-pol

• Acq. date

June 12, 2008 (1 hour) Forest type Temperate Topography Moderate slopes Height 25 ~ 35m Species

• N. Spruce, E.

Beech, White Fir Biomass 40 ~ 450 t/ha

Height Point-Spread Functions (PSF)

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Microwaves and Radar Institute

Tomographic slices & profiles (1/2)

Range bin 364 Range bin 500 Range bin 584 HH HV

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Microwaves and Radar Institute

Tomographic slices & profiles (2/2)

PCT profiles can be calculated also with a very low number of baselines

Master B1 B2 From full-baseline profiles to dual baseline profiles

Microwaves and Radar Institute > 30.05.2006

Microwaves and Radar Institute

50 40 30 20 10 0m

Traunstein test site: a preliminary validation

Measured Measured PCT PCT

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Microwaves and Radar Institute

Some conclusions

Multi-baseline Pol-InSAR techniques for biomass estimation: Here we are… Accurate (<10%) estimation of forest top height at high spatial resolutions (20-50m grid); vertical “radar” forest structure achievable by means of a “realistic” number of acquisitions. Potentials… Structure-based (AG) biomass estimators promise accuracy and stability across very different forest conditions; PCT shows potentials for biomass estimation even with dual baseline data. Challenges… Mapping of “radar” structure to biomass structure needs to be further investigated, especially with reference to acquisition-dependent parameters (frequency, polarization, temporal decorrelation…).

Microwaves and Radar Institute > 30.05.2006

Microwaves and Radar Institute

Biomass Estimation from Forest Vertical Structure: Potentials and Challenges for Multi-Baseline Pol-InSAR Techniques

• M. Pardini, F. Kugler, S.-K. Lee, S. Sauer, A. Toraño Caicoya & K. Papathanassiou

Microwaves and Radar Institute (DLR-HR) German Aerospace Center (DLR)

Thank you! … Questions?