The CHRIS/PROBA Jornada Experiment: Exploitation of Data from the CHRIS Mark J. Chopping Department of Earth and Environmental Studies Montclair State University April 4, 2003

The CHRIS/PROBA Jornada Experiment: Exploitation of Data from the CHRIS Collaborators: Mark Chopping, Earth and Environmental Studies, Montclair State University Thomas Schmugge, USDA, ARS Hydrology & Remote Sensing Laboratory Albert Rango, USDA, ARS Jornada Experimental Range Jerry Ritchie, USDA, ARS Hydrology & Remote Sensing Laboratory Charles Walthall, USDA, ARS Hydrology & Remote Sensing Laboratory Lihong Su, Research Ctr. for Remote Sensing, Beijing Normal University. William Kustas, USDA, ARS Hydrology & Remote Sensing Laboratory Previously: Physical Structure and Composition of Desert Grasslands and Shrublands via Hyperspectral Multiple View Angle (MVA) Reflectance Data from the CHRIS sensor on PROBACHRIS/PROBA PLANNING MEETING ESA-ESTEC Noordwijk 4th/5th July 2000 Physical Structure and Composition of Desert Grasslands and Shrublands via Hyperspectral Multiple View Angle (MVA) Reflectance Data from the CHRIS sensor on PROBA CHRIS Jornada Experiment

Preparation for the Exploitation of Data from the CHRIS over the Jornada: 1.Multi-Angle Observations (MAO) from Air 2.A Simplified Geometric CR Model 3.Field Data Collection (canopy maps, detailed plant measurements, radiometry/spectroscopy) 4.Radiosity Graphics Method (RGM): cross- validation between RGM, SGM and MAO 5.PROBA orbital prediction from TLEs (angles) 6.Registration of CHRIS images 7.Multiband Radiometer (Langley Analysis)

Location of the Jornada Core Site and Transition Study Area CHRIS Jornada Experiment airphotogrid Grid = 25 m plots

Jornada Transition Study Area BRDF effects are big soils are bright, so shadows have greater impact red w.length has largest contrast CHRIS Jornada Experiment

SCALE MATTERS! Previously we only had Multi-Angle Observations meter & km scales… However we m CHRIS Jornada Experiment

25 miles We know that MAO provide information on the surface not available via other methods: these images were obtained using only ONE AVHRR spectral band. CHRIS Jornada Experiment 50 miles NOAA AVHRR,1.1km+

meter scales: ground and tower radiometry km scales: AVHRR, POLDER, EOS satellites m observations are only possible from the AIR (or rather, were) CHRIS Jornada Experiment

University of Chiba (Japan) Centre For Remote Sensing Applications gathers POINT (1-D) BRDF data over the Jornada, w/PC-controlled helicopter, 16m IFOV 2.5 m CHRIS Jornada Experiment

Courtesy: USDA, ARS Aerial acquisition can provide good multi-angle sampling. Photo: setting markers for the flights, 09/2002.

BRDF SAMPLES from the Air: w e used a Duncan tilting, digital, multi-spectral camera to acquire MAO images in the Principal 3 sun angles. t=5 t=4 t=3 t=2 t=1 t=0 Images of view zeniths CHRIS Jornada Experiment

Flightlines (Cessna 404/DuncanTech Camera) CHRIS Jornada Experiment

Typical angular sampling for ONE point CHRIS Jornada Experiment

Multi-angle Reflectance Images over the transition test site from the air: 2-D BRDF for the first time. CHRIS Jornada Experiment

The image set overlap: coverage is variable (8-17 samples) but still provides for a wide variation in upper canopy/understory density and soil exposure. CHRIS Jornada Experiment

Spectral reflectance at 650 nm 300 m Coverage is variable (8-17 samples per location) but still provides for a wide variation in upper canopy & understory density and soil exposure.

Canopy reflectance and radiosity models must be driven by plant and soil measurements from air and field. CHRIS Jornada Experiment

Frequency distribution of plant heights in two 25m 2 plots (1,250 sq m). Sample field data sheet for the small plant (understory) survey (dimensions of all the plants were recorded). Plant Survey and Mapping Honey mesquite (Prosopis glandulosa) Map of one 25 m 2 plot near the JORNEX grass-shrub transition site, showing the locations and heights in cm of large shrubs (grey polygons) and the locations of small plants (dots) such as broom snakeweed (sparse in this plot relative to other plots in the vicinity). CHRIS Jornada Experiment

Calibration of the Duncan camera images was checked by reference to BRFs over tarps. Atmospheric modeling used 6S (Vermote et al., 1997), v4.2. CHRIS Jornada Experiment

Modeling Canopy Reflectance CHRIS Jornada Experiment

The Radiosity Graphics Method Stores 3-D computer models of plants Needs shapes/brightness of plants + locations Driven by plant maps and field spectroscopy Light scattering is handled explicitly (few assumptions, approximations)… …but cannot be inverted easily CHRIS Jornada Experiment

Solar zenith angle = 37°   = probabilities x direct:diffuse ratio x spectral reflectance of plant types CHRIS Jornada Experiment

Top: Aerial photograph chips (25 m 2 ) for sparse plots (L) and dense plot (R). Bottom: views of the plants in modeled as spheroids, and their shadows. CHRIS Jornada Experiment 25 m Canopy 3-D simulations using radiosity modeling with air- and field- acquired measurements

Views of sparse snakeweed plot generated at various angular configurations by the Radiosity Graphics Method (a) (b) (c) CHRIS Jornada Experiment

Views of dense snakeweed plot generated at various angle configurations by the Radiosity Graphics Method (a) (b) (c) CHRIS Jornada Experiment

Simple Geometric Model (SGM)  designed for invertibility (has to be simple, with small # parms.)  invert = MAO in ---> information out  Uses principles of Boolean geometry + RT (empirical coupling)  Parameters are mean plant # density, width, height, shape, soil/understory BRDF.  Must first be tested and validated… CHRIS Jornada Experiment

SGM Sensitivity Tests: Change in output with mean plant radius (similar results for density, height and shape). CHRIS Jornada Experiment

Validation: Bi-directional Reflectance Factors from the Radiosity Graphics Method (RGM) and the Simple Geometric Model (SGM) assessed against each other (a) sparse plot (b) dense plot. CHRIS Jornada Experiment

Validation against MAO. Progress but still work to do: Refining models New (better) data Determining which assumptions are poor CHRIS Jornada Experiment (d), (e), (f) Dense case (a), (b), (c) Sparse case Solar Zenith = 38° Solar Zenith = 49°Solar Zenith = 59° View Zenith Angle (°) RGM w/snakeweed “removed” Observed (DuncanTech camera) RGM w/non-Lambertian soil SGM (h/b=2.92) (a)(b)(c) (d)(e)(f)

Inversion of SGM With MAO (transition site) INVERSIONS: (a) LAI, rescaled (b) shrub density (c) RMSE (d) fractional cover. Brighter = higher values. REFERENCE : L: 1m panchromatic IKONOS image R: 4m MSAVI 2 IKONOS image (a)(b)(c)(d) CHRIS Jornada Experiment

FIRST CHRIS IMAGE ACQUIRED over the JORNADAEXPERIMENTALRANGE FIRST CHRIS IMAGE ACQUIRED over the JORNADAEXPERIMENTALRANGE CHRIS Jornada Experiment

Aug 5, 2002 (browse only in Nov’02) CHRIS Jornada Experiment

CHRIS/PROBA 08/05/02 Chihuahuan Desert, S.NM 18 wavelengths multi-view angle18 wavelengths multi-view angle CHRIS Jornada Experiment 800 meters cloud cloud- shadow Aeolian soil erosion & deposition remnant desert grassland prevailing wind direction swales Desert shrubland (mesquite) Bands 17,9,1 Roads & fencelines

CHRIS/PROBA 08/05/02 Chihuahuan Desert, S.NM 18 wavelengths multi-view angle18 wavelengths multi-view angle 800 meters Transition (grass- shrub) remnant grassland swale desert shrubland Aeolian deposition Spectral Sampling Sites CHRIS Jornada Experiment

PROBA ORBIT over the Jornada (5th Aug. 2002) Xephem prediction from NORAD TLEs

CHRIS Jornada Experiment The Future: More modeling… More fieldwork… More validation… More data from CHRIS (five looks please!)