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

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

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

Test Site at Remningstorp Estate, Sweden 1200 hectars divided into over 300 stands Test site location Stand-level biomass: 0-370 tons/ha Ground topography: 110–150 m asl

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

BioSAR 2010: Data collections Airborne SAR data using ONERAs SETHI system P-band (260-460 MHz) and L-band (1250-1400 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

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

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

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

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

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 271-214: young forest plots

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 2010-11 Additional plots are being measured during summer 2011 271-214: young forest plots

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

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

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

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.