S. Jacquemoud & L. Bousquet Institut de Physique du Globe de Paris Space Studies and Planetology Université Paris 7 - Denis Diderot Department of Earth, Environmental, and Planetary Studies Modeling spectral, directional, and emissional leaf optical properties: past, present, future

Biochemical leaf composition water (vacuole): 90-95% dry matter (cell walls): 5-10% - cellulose: 15-30% - hemicellulose: 10-30% - proteins: 10-20% - lignin: 5-15% - starch: % - sugar - etc. A typical cell of a green-fresh leaf contains: chlorophyll a and b (chloroplasts) other pigments - carotenoids - anthocyanins, flavons - brown pigments - etc. B. Hosgood, S. Jacquemoud, G. Andreoli, J. Verdebout, A. Pedrini & G. Schmuck, 1994, Leaf Optical Properties EXperiment 93 (LOPEX93), Joint Research Centre, Ispra, Italy.

Anatomical structure of a typical dicot leaf Lower epidermis Cross section upper epidermis lower epidermis palissade parenchyma spongy mesophyll stomata

Tessa Traeger, 1997, Sight transmitted + emitted absorbed reflected + emitted T.R. Sinclair, M.M. Schreiber & R.M. Hoffer, 1973, Diffuse reflectance hypothesis for the pathway of Solar radiation through leaves, Agronomy Journal, 65: Propagation of photons in a leaf

Bidirectional properties Bidirectional Reflectance Distribution Function D. Combes, L. Bousquet, S. Jacquemoud, H. Sinoquet, C. Varlet-Grancher & I. Moya, 2006, A new spectro-photo- goniometer to measure leaf spectral and directional optical properties, Remote Sensing of Environment, submitted.

Bidirectional properties: effect of surface roughness specular effect LaurelEuropean beechHazel roughness L. Bousquet, S. Lachérade, S. Jacquemoud & I. Moya, 2005, Leaf BRDF measurement and model for specular and diffuse component differentiation, Remote Sensing of Environment, 98:

chlorophyll achlorophyll b  -carotene Absorption by foliar pigments anthocyanin + glucose a b

Absorption and emission of chlorophyll a Chlorophyll a solution in methanol Source : Juliette Louis (ESE-CNRS)

Spectral properties VISNIRSWIR Trifolium pratense Directional Hemispherical Reflectance Function

 anthocyanins  carotenoids  brown pigments  chlorophylls Spectral properties: effect of leaf pigments

corn (Zea mays)sunflower (Helianthus annuus) Spectral properties: effect of leaf internal structure

Moldau (1967), Allen et al. (1969, 1970), Gausman et al. (1970), Jacquemoud et al. (1990, 1996, 2000, PROSPECT), Fourty et al. (1996), Baret & Fourty (1997) (1) Plate models N couches   z = 0 z = N  = J(0)  = I(N) J I Allen & Richardson (1968), Andrieu et al. (1988), Fukshansky et al. (1991), Yamada & Fujimura (1991), von Remisowsky et al. (1992), Conel et al. (1993), Richter & Fukshansky (1996) (2) N-flux models

(3) Melamed model Dawson et al. (1995, 1997, LIBERTY) (4) Radiative transfer equation Ma et al. (1990), Ganapol et al. (1998, LEAFMOD), Berdnik & Mukhamed’yarov (2001), Wang et al. (2005)

(5) Stochastic models Tucker and Garratt (1977, LFMOD1), Lüdeker and Günther (1990), Maier et al. (1997, 2000, SLOP), Baranoski and Rokne (1997, 1998, 2000, ABM, 2006 ABM-B and ABM-U) (6) Ray tracing models   Allen et al. (1973), Kumar & Silva (1973), Govaerts et al. (1996, RAYTRAN), Jacquemoud et al. (1997), Ustin et al. (2001)

plate model N plates model W.A. Allen, H.W. Gausman, A.J. Richardson & J.R. Thomas, 1969, Interaction of isotropic light with a compact plant leaf, Journal of the Optical Society of America, 59: G.G. Stokes, 1862, On the intensity of the light reflected from or transmitted through a pile of plates, Proceedings of the Royal Society of London, 11: PROSPECT: principle

N C ab C w C m PROSPECT  ( )  ( ) leaf structure parameter chlorophyll a+b concentration (  g.cm  2 ) equivalent water thickness (cm) dry matter content (g.cm  2 ) N = 1.5, C ab = 50  g.cm  2, C m = g.cm  2 PROSPECT: direct mode

PROSPECT: sensitivity analysis Leaf structure parameter, N Chlorophyll content, C ab Equivalent water thickness, C w Dry matter content, C m Sum of the contributions to reflectance Source: Gabriel Pavan (LED)

P. Bowyer, C. Bacour, S. Jacquemoud, F.M. Danson, 2006, Global sensitivity analyses in remote sensing, in preparation. PROSPECT: sensitivity analysis

PROSPECT: model inversion model measurement