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Modeling directional reflectance spectra of coastal marsh vegetation for remote sensing applications. Proposal Defense Kevin Ross Turpie Dept of Geography University of Maryland 6 December 2006. Dr. Michael Kearney Dr. Stephen Prince Dr. Michelle Hofton Dr. Robert Hudson
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Modeling directional reflectance spectra of coastal marsh vegetation for remote sensing applications Proposal Defense Kevin Ross Turpie Dept of Geography University of Maryland 6 December 2006 Dr. Michael Kearney Dr. Stephen Prince Dr. Michelle Hofton Dr. Robert Hudson Dr. David Tilley
Brackish and Salt Marshes • CHARACTERISTICS: • Important habitat for coastal flora and fauna. • High primary productivity (0.5 to 6.2 kg C m-2 yr-1) (Day et al. 1989). • Strong nutrient sink - reduces eutrophication. • Sediment sink - reduces silting. • Wave energy sink - protect coasts. • Key pathway of detritus and CDOM to coastal systems. • (Bouchard et al. 2003, Mendonca et al. 2004) • Salinity and hydrology produce characteristic zonation. • Inundated graminaceous and herbaceous monospecific canopies.
Brackish and Salt Marshes • ISSUES: • Sea level rise - drown marsh, increase erosion, change hydrology and salinity gradient. • Disturbances • Storms - effect hydrology, nutrient flux, erosion. • Construction - effect nutrient flux and hydrology. • Fire - can damage rhizomes, effects not fully understood. • Invasive Species - can affect trophic, edaphic, hydological characteristics of the marsh.
Statement of Problem • BRDF of vegetation canopies changes with wavelength, thus spectral features change with viewing and solar angles. • This affects remote sensing techniques that depend on the marsh spectral characteristics (e.g., classification). • This can be compensated for with a canopy RT model, but water produces BRDF affects in inundated canopies that is not handed by current models.
Example: BRDF Effects from Water Data provided by Schill (Schill 2004). from Vanderbilt et al. 2002, with permission
Spartina patens Schoenoplectus americanus Water Level 10 Water Level Reflectance (%) Reflectance (%) 25 20 15 10 900 0 1000 30 700 5 0 12 6 14 16 700 800 900 1000 4 8 800 2 Wavelength (nm) Wavelength (nm) Example: Spectral Effects of Water Data digitzed from Stutzer 2004
PROPOSED THESIS RESEARCH • Objective: Develop an RT model for the marsh canopy. • Development - Build RT model on existing work. • Validation - Validate the model against field data. • Model Inversion - Test model inversion against field data. • Closure Experiment - Test agreement of model, ground truth, and RS data. • Geometric Optimization - Optimize viewing and solar angles for best vegetation spectral signature.
Role of a Marsh Canopy RT Model Invert Model • Canopy Structure • Geochem Cycling • Coastal Ecology Remote Sensing Imaging • Albedo • Light Field / FPAR Integrate Model • Productivity • Energy Budget • Climatology • Image Comparison • Classification • Vegetation Indices • Apps for RS Adjust for BRDF • Invasive Species • Dieback • Regn Monitoring Applications for RS • Geochem Cycling • Coastal Ecology • Standing biomass • Litter Decomposition • Productivity • Sub-lethal Stress Field Radio- metry Adjust for BRDF • Local Monitoring • Vic Cal • Validation • Tie to RS Imaging
Marsh Canopy Radiative Transfer Model Model Selection Criteria • Accounts for majority of variation in BRDF. • Few input parameters. • Invertible. • Accessible code. • Flexibility of design and implementation. Modifications • Must add aquatic background (Water RT). • May need to generalize for RS applications. • Any parameterization done against training data.
Marsh Canopy Radiative Transfer Model CANOPY i Air-Water Interface WATER t SOIL
Marsh Canopy Radiative Transfer Model Sample of Existing Models 3-D Ray-tracing Raytran Govaerts & Verstraete 1998, SPRINT Goel & Thompson Radiosity / Rectangular Cell Kimes et al. 1984, DART Gastellu-Etchegorry et al. 1996 Röhrig et al. 2000 1-D Turbid Medium Kubelka Monk 1931 Duntley 1942 Allen Gayle & Richardson 1971 Suits1972 SAIL Verhoef 1984 DISORD Myneni et al. 1988 Geometric Optical CR Kuusk 1995, 1996 MCRM Kuusk 1995, 1-D (Markov Chain) IAPI Iaquinta et al. 1997 NADIM Gobron et al. 1997 2-Layer Kuusk 2001 Ni et al. 1999 FLAIR White et al. 2001 Kernel Ross 1981 Strahler & Jupp 1991 Ross-thick Roujean et al. 1992 RPV Rahman et al. 1993 Walthall 1995 Ross-thin Wanner et al. 1995 Li-sparse Wanner et al. 1996 Bicheron & Leroy 2000 MRPV Martonchik et al. 2002 SGM Chopping et al. 2003 Hybrid SAIL-H Kuusk, GeoSAIL Huemmrich 2001 García-Haro & Sommer 2002
Field Data • Phase I - Locate sites and plan itinerary. • Phase II - Measurements: • Multiple monospecific canopy types. • BRF on SPP from 60º to 60º. • Plant R and T. • LAI, LAD, Height. • Soil and water samples - optics. • Tide, weather, salinity. • Digitial photos.
Validation and Closure • Validation • Constrained optimization to fit model to validation dataset from field data. • Test hypothesis that model fitted input and results are within confidence intervals for observations. • Inversion - Invert model for comparison with field data (no constraints). • RS Closure - Compare with data at remote sensing scales. Key candidates: • AISA - airborne hyperspectral, with roll maneuver • CHRIS / Proba - ESA sat with5 angles, hyperspectral
Geometry Optimization • Create “pure” vegetation spectral signature. • leaf reflectance and transmittance. • modeled BRDF for dense canopy and “black background.” • Create synthetic dataset from field data for canopy and background conditions. • Autocorrelate veg signature across entire modeled BRDF. • Use results to identify regions of viewing and solar angles ideal for identification (e.g., spectral angle type classification). • See if inverse of the model improves in these regions.
Disseminating Results Primary Publications Proposed
Disseminating Results General Structure of Proposed Dissertation
Work so far… • Literature search. • Contacted and/or met with many researchers. • Consulted and observed researchers doing field work. • Spoke with government and other groups on marsh issues. • Acquired marsh BRDF data and leaf optics and analyzed. • Acquired several models and did initial experiments. • Explored several coastal marshes by boat, SUV, and foot. • Wrote proposal for special use permit of CBMNWRC. • On science team for CBMNWRC; expected to file regular reports. • Wrote proposal for CHRIS/Proba data. • SpecTIR Corp has agreed to shoulder IR&D costs for AISA flight. • Got approval for radiometry instruments from GSFC. • Have access to lab equipment for water analysis at GSFC. • Got back-up and lab equipment at USDA. • Borrowing a ASD handheld spectrometer. • Attended data user workshop for MISR.
Work so far… Analysis of Schill BRDF data for Spartina alterniflora data from Schill, TNC data from Ramsey and Rangoonwala, USGS
Viewing Angle (º) Work so far… NADIM Run Compiled and ran models NADIM MCRM RPV, MRPV SAIL SAIL-H GeoSAIL data from Ramsey and Rangoonwala, USGS
Work so far… Adviser, discussions on research topic. Marsh field trip, April 2006 Discussions on marsh research, 2005 SAIL model, BRDF info Contacts on marsh research Talks & meeting on marsh field work Discussion, supported marsh RT model Field work experience and discussion Discussion on modeling canopy RT USDA contact, met and discussed work USDA contact, met and discussed work Info and advise on marsh work Discussed modeling canopies Discussed modeling canopies Hyperion project scientist Experience with CDOM measurements Discussed flyover of LIDAR Discussed flyover of LIDAR Discussed radiometry and BRDF Discussed goniometers, toured facility Dr. Michael Kearney Dr. David Tilley Dr. Andy Rogers Dr. Fred Huemmrich, UMBC Dr. Victor Klemas, U of Del Dr. Richard Field, U of Del Dr. John Jensen, U of SC Dr. Betsy Middleton, NASA Dr. John Norman, U of Wisc Dr. Martha Anderson, USDA Dr. Charlie Walthall Dr. Andrew Baldwin, UMCP Dr. Narandra Goel Dr. Wenhan Qin Dr. Steven Unger, NASA Dr. Antonio Mannino, NASA Dr. Wayne Wright, NASA Dr. Amar Nayegandhi, USGS Dr. James Irons, NASA Dr. James Butler, NASA
Work so far… Dr. Vern Vanderbilt, NASA Dr. Lawrence Corps, USDA Roger Stone, US FWS Dr. Dixie Birch, US FWS Dr. Glenn Carowan, US FWS Dr. Craig Daughtry, USDA Dr. Nancy Adamson, U of Md CE Leslie Hunter-Caro, Environmental Concern Penny Grealy, Environmental Concern Dr. David Nemerson, National Aquarium Dr. LeeAnne Chandler, DNR Dr. Roman Jensien, MCBP Jay Charland, Assateague Coast Keeper Dr. Darlene Wells, DNR/MGS Dr. Fred Irani, DNR Dr. Court Stevenson, UMCES Dr. Steven Schill Dr. Amina Rangoonwala, USGS Dr. Elijah Ramsey III, USGS Dr. Oliver Weatherbee, SpecTIR Corp.v Lengthy discussion on RT and RS. Radiometric field work CBMNWRC info, tour of Blackwater CBMNWRC info, handled proposal CBMNWRC info, proposal info Radiometric field work Contacts on growing S. alterniflora Info on growing S. alterniflora Info on growing S. alterniflora Info on growing S. alterniflora Contacts on critical areas Tour of two coastal bay marshes Tour of one coastal bay marsh Info on critical areas Info on RS work, contacts on field work Discussion on research topic S. alterniflora BRDF Data Optic data and papers Optic data and papers SpecTIR contact, info on AISA
Work so far… Discussed marsh spectra and instruments Discussed marsh classification & collab Contacts for instrument and data MISR proj scientist, PARABOLA III Advice and help with GSFC rad inst Info on marsh field work Discussion on marsh BRDF and RS Discussed measuring BRDF Discussed measuring BRDF and DART Discussed instruments for BRDF Lengthy discussion on BRDF and RS Provided paper on sun glint work Lengthy discussion on BRDF field inst Info on flight cost, photos, etc. Info on KNMEC and Bishop’s Head Info on KNMEC Info on DNR mapping resources Info on ASD resources Contact for Hyperion data Tour and overview of GSFC goniometer Dr. Francisco Artigas, MERI Dr. Martha Gilmore, Wesleyan U Dr. William Lawrence, BSU Dr. David Diner, NASA Milton Hom, NASA Amy Jacobs, Delaware DNR Dr. Ann Nolin, OSU Dr. Don Deering, NASA Dr. Dan Kimes, NASA Dr. V. Martins Dr. Ray Hunt, USDA Dr. Susan Ustin, UCD/CSTARS Dr. Mark Chopping, Montclair State U Kent Lawrenson, DCAir Photos Cassy Gurbisz, CBF Matt Mullin, CBF Kevin Boone, DNR David Hatchell, ASD Inc. Lawrence Ong, SSAI Georgi Georgiev, SSAI
Flow of Planned Research Tasks and Products Task Flow Diagram Generate Synthetic Data Research Products Characterization of canopy reflectance for marsh canopies Develop Model Collect Field Data Characterization of canopy structure parameters Directional reflectance model for marshes Validate Model Model inversion using ground truth Optimize Geometry Strategy for measuring canopy reflectance Validated of model for remote sensing Obtain and Process RS Data Closure Experiment Validation of optimized geometry Inversion of model using remote sensing data
Study Sites Blackwater Lake Crocheron Fishing Bay Maple Dam Road Bishops Head Marsh Hoopers Strait
Schneider et al. 2004 Kuusk 2004 http://www.aai.ee/~andres/fieldwork.html 2006/12/05 Schill 2000 Walter-Shea, Mesarch 1998 http://snrs.unl.edu/okarmcart/Addedphotos.html 2006/12/05 Kuusk 2004 http://www.aai.ee/~andres/fieldwork.html 2006/12/05
Terminology of Radiometry Radiant Flux (Energy / time) (Joules / s or Watts) (Watts m-2 sr-1) Radiance (Watts m-2) Irradiance
Terminology of Radiometry Specular reflectance
Terminology of Radiometry Bidirectional Reflectance Distribution Function (BRDF) (sr-1) Bidirectional Reflectance Factor (BRF)
Terminology of Radiometry • IMPORTANT PROPERTIES OF BRDF • Inherent optical property: is independent of source or receiver. • Instantaneous quantity: can only be approximated in the real world; usually by measuring BRF. • Can vary with the wavelength of light, so spectra can change with geometry. • BRDF is dependent on: • underlying structure of the reflecting medium, • optical properties of the medium’s constituents, • optical properties of the medium’s background.
Sky Veg Air- Water I/F Under Water Bottom Sensor Marsh Canopy Radiative Transfer Model
BRDF Spectral Effects in Grass Backscattering Forward Scattering Sun in front of viewer Sun behind viewer Photos from Sandmeier et al. 1999