Coastal wetland monitoring using multi-frequency polarimetric SAR - PowerPoint PPT Presentation

POLINSAR 2009 Coastal wetland monitoring using multi-frequency polarimetric SAR Sang-Eun PARK 1 , W ooil M. MOON 2 ,3 , Duk-jin KI M 3 , and Eric POTTI ER 1 1. University of Rennes 1, IETR, Bat 11D, 263 Avenue General Leclerc, 35042 RENNES, France. 2. Geophysics, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. 3. School of Earth and Environmental Sciences, Seoul National University, Gwanak-gu, silrim-dong, Seoul 151-747, Korea

SAPHIR Introduction � Tidal wetlands (intertidal flats) � zones of interaction between marine and terrestrial environments � Highly productive fishery areas and have dynamic and diverse ecosystems. � Need environmental management � High development pressure (e.g. reclamation and marine pollution) � Highly vulnerable to climate changes. • Objective: Quantitative estimation of the surface geophysical parameters in tidal wetlands from polarimetric SAR data sets 2

SAPHIR Study Area – Suncheon Bay Suncheon City AIRSAR NASA/JPL Suncheon Bay 2 - T A S R A D A Goheung City R 3

SAPHIR Study Area – Suncheon Bay 4

SAPHIR Geophysical Parameter Retrieval Dielectric constant Θ = Height distribution ( s ) ( ) Θ → Ω Autocorrlation ( l ) � Forward Scattering models F Independent combination of Ω = polarization measurements � I ntegral Equation Method [Fung et al., 1992; Fung, 1994; Wu et al., 2001 ] ( ) ( ) ∞ − 2 j ( 2 , 0 ) k W k ∑ σ = − 0 2 2 2 j 2 z exp 2 k s s I PP z PP 2 ! j = 1 j � Extended-Bragg Model [Schuler et al., 2002; Hajnsek et al., 2003] � Coherency m atrix ( Bragg scatter and the orientation of facets) ⎡ ⎤ − σ 2 exp( 2 ) 0 C C rms slope 1 [ 2 ] ⎢ ⎥ σ = m = − σ + − σ * 2 2 s [ ] exp( 2 ) 1 exp( 8 ) 0 T ⎢ C C ⎥ θ sin 2 3 [ ] 2 ⎢ ⎥ − − σ 2 0 0 1 exp( 8 ) C ⎣ ⎦ 3 � Finding the set of unknown surface parameters from ( ) Θ = − 1 Ω F polarization measurement 5

SAPHIR Roughness Retrieval � Surface sediments can be assumed to be fully saturated with water throughout intertidal mudflats. � The effect of the dielectric constant on backscatter signals can thus be neglected in the specific case of the intertidal mudflats. � The intertidal mudflat is an ideal study site for the reduction of surface variables. � Roughness parameters can be estimated from two independent polarization observations. Inversion from co-pol using IEM Inversion using the extended-Bragg ⎡ ⎤ 2 ⎡ ⎤ + ⎡ ⎤ σ ⎡ ⎤ s 0 S S s − = ⎢ ⎥ 1 = − HH VV 1 ⎢ ⎥ G ⎢ HH ⎥ ⎢ ⎥ F ρ σ ⎣ ⎦ ⎢ ⎥ l 0 ⎣ ⎦ ⎣ ⎦ l ⎣ ⎦ RRLL VV 6

SAPHIR Experimental Results – AIRSAR PACRIM-2 (2000.09.30) NASA/JPL AIRSAR L-band, Full-pol 7

SAPHIR Experimental Results – AIRSAR Correlation length rms height 0 0.4 cm 0 6 cm σ σ 0 0 2 σ σ 2 ρ + ρ + from , 0 0 l from , from , from , l S S s s S S HH VV RRLL HH VV HH VV RRLL HH VV rms error of the rms height rms error of the correlation length 0.1 0.1 8.4 3.8 8

SAPHIR o Fine Quad Pol (FQ6) o Incidence angle: 24.5 ° ~26.4 ° o Ascending o 2008.12.14 RADARSAT-2 9

SAPHIR Experimental Results – RADARSAT-2 rms height from rms height from AIRSAR RADARSAT-2 0.3cm 0 1 0

SAPHIR Experimental Results – RADARSAT-2 AIRSAR RADARSAT-2 2000.09.30 2008.12.14 1 1

SAPHIR Experimental Results – RADARSAT-2 rms height AIRSAR RADARSAT-2 2000.09.30 2008.12.14 0 0.7 cm 1 2

SAPHIR Study Area – Kyunggi Bay R A S L A P S O L A SEOUL o 2007.04.13 o Quad Pol Mode o Ascending o Incidence angle: 21.5 ° R A D A R S A T - 2 o 2008.11.21 o Quad Pol (FQ16) o Descending o Incidence angle: 35.5 ° ~37.0 ° 1 3

SAPHIR ALOS PALSAR Natural intertidal m udflats Sea dike � Surface sediments are saturated with sea water Reclaim ed m udflats � Surface water drained out � Mud crack developed 1 4

SAPHIR Geophysical Parameter Inversion � Roughness Inversion for reclaimed mud flats � Impossible to reduce the number of surface variables � Fully polarimetric inversion ⎡ ⎤ + ⎡ ⎤ 2 | | S S m V HH VV ⎢ ⎥ ⎢ ⎥ − = ρ RRLL 1 | | s F ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ α ⎣ ⎦ l ⎣ ⎦ 1 � Simulations Soil Min. Max. Interval parameters m V 0.1 0.6 0.01 s 0.1 cm 1.5 cm 0.1 cm 1 5 l 1 cm 15 cm 0.1 cm

SAPHIR Experimental Results – PALSAR Moisture content Correlation length rms height Reclaimed mudflat Intertidal flats Reclaimed mudflat 0 m V 0.6 0 l 12 cm 0 s 0.4 cm 1 6

SAPHIR Experimental Results – PALSAR � rms heights � probably connected with the surface sediment texture of the intertidal flats [Korea Ocean Research & Development Institute, 2004] 1 7

SAPHIR Experimental Results – RADARSAT-2 Moisture content rms height (PALSAR) rms height Reclaimed mudflat Correlation length Intertidal flats 0 m V 0.6 Reclaimed 0 s 0.3 cm mudflat � Lim itation of m odel � Calibration � Missing param eter 0 l 10 cm 1 8

SAPHIR Future Study R A S L A P S O L A SEOUL TerraSAR-X R A D A R S A T - 2 TerraSAR-X 1 9

SAPHIR RADARSAT-2 2008.11.21 Future Study PALSAR 2007.04.13 2 0

SAPHIR Conclusions � Application of polarimetric SAR data for intertidal flats was investigated with inversion of the roughness characteristics of surface sediments. � First results of surface roughness parameters retrieval from L-band and C-band space-borne polarimetric SAR observations. � Continuous monitoring using the multi-temporal, multi-frequency space-born SAR data sets, such as ALOS PALSAR (L-band), RADARSAT-2 (C-band), and TerraSAR-X (X-band). 2 1