1. BioSAR 2010 – A SAR campaign in support to the BIOMASS mission
Lars Ulander, Anders Gustavsson
Swedish Defence Research Agency (FOI), Sweden
Pascale Dubois-Fernandez, Xavier Dupuis
Office National d’Études et de Recherches Aérospatiales (ONERA), France
Johan Fransson, Johan Holmgren, Jörgen Wallerman
Swedish University of Agricultural Sciences (SLU), Sweden
Leif Eriksson, Gustaf Sandberg, Maciej Soja
Chalmers University of Technology, Göteborg, Sweden

2. BioSAR 2010: Background
ESA has funded multiple SAR campaigns in support of the P-band BIOMASS satellite candidate mission
Tropical rain forest
2009: TropiSAR in French Guiana
Boreal forest
2007: BioSAR-1 in Sweden (Remningstorp)
Demonstrated high temporal coherence over 2 months
Developed soil moisture corrections using multiple dates
2008: BioSAR-2 in Sweden (Krycklan)
Developed topographic corrections using multiple headings
BioSAR 2010 in Sweden (Remningstorp) ← this presentation

3. BioSAR 2010: Objectives
Ability of detecting, mapping and updated retrieval of changes in forest parameters (due to forest growth or disturbances such as thinning or clear-cuts)
Cross-calibration between the ONERA SETHI airborne SAR system (used in 2010) and DLR E-SAR (2007)
Robustness of biomass retrieval algorithms with respect to changes in forest conditions
Long-term coherence of P-band over forested and other natural surfaces

4. Test Site at Remningstorp Estate, Sweden
1200 hectars divided into over 300 stands
Test site location
Stand-level biomass: tons/ha
Ground topography: 110–150 m asl

5. Remningstorp: Tree species
Photos of Norway spruce, Scots pine and birch stands

6. BioSAR 2010: Data collections
Airborne SAR data using ONERAs SETHI system
P-band ( MHz) and L-band ( MHz), full polarimetry
10 data acquisition tracks in one flight mission
2 tracks from 2007 repeated to study long-term coherence (challenge!)
Vertical offset for PolInSAR (horizontal offset used in 2007)
3 headings to study topographic corrections (2 headings used in 2007)
Helicopter lidar data using TopEye MKIII
Small footprint (< 0.2 m) and high pulse density (> 10 pulses/m2)
In situ data
Field notes, soil moisture and weather data during the flight
Extensive forest field measurements after the flight
Maps of clearings and thinnings between 2007 and 2010

7. SAR flights by ONERA on 23 September
SETHI SAR system
P + L, full polarimetry
Two calibration trihedrals

8. Geocoded SAR images (3 headings)
R=HH, G=HV, B=VV
Geometric error < 2m

9. Helicopter lidar data collection
Lidar data in 2007 covered only central part
Lidar data in 2010
covered the full extent of the test site

10. Lidar DSM 0.5 raster cell size
Classification of ground/non-ground: TerraScan from Terrasolid ( DEM: average of ground-points within raster cell, TIN-interpolation of empty raster cells. 10

11. Field Inventory (200-m grid) by SLU
10 m radius plots
Species and diameter for all trees (>40 mm dbh), height and age for a subsample
Site variables (field layer, soil type, peat/mineral soil, lateral water movement, production capacity, ground structure)
Accurate determination of plot center using post-processed dGPS
Total 271 plots surveyed, 214 of these in forest > 50 mm mean dbh
: young forest plots

12. Field Inventory (individual trees) by SLU
Ten 80 m x 80 m square plots defined and measured in 2007
All trees with dbh > 50 mm marked with number tags
Accurate determination of position using post-processed dGPS
Seven plots remained in 2010 after three were clear-cutted
Species, dbh updated
Additional plots are being measured during summer 2011
: young forest plots

13. Initial SAR imagery comparison
E-SAR 2007
SETHI 2010
HH = red
HV = green
VV = blue
Images geocoded to UTM 33 N
SETHI has higher (2x) bandwidth

14. Initial SAR imagery comparison
E-SAR 2007
SETHI 2010
HH = red
HV = green
VV = blue
Clear-cutting easily delineated (red circles)
Thinning and growth result in subtle changes

15. First analysis of mapping changes
Lidar: Biomass
SAR: PHV-pol PHH-pol PVV-pol
Color-coded change images 2007 vs 2010
Red: Lower value in 2010
Cyan: Higher value in 2010
Gray: Unchanged value
thinning
clear cut

16. Conclusions All planned P/L SAR data acquisitions were collected
10 successful passes; 6 processed and calibrated
Ground data collected according to plan
Lidar data processed and biomass maps produced
Processing of forest field data partly done
First results
Data are generally of very high quality
Change maps from P-band SAR images (SETHI 2010 vs E-SAR 2007) delineate clear-cuts but also other forest features – to be further investigated.