1 / 22

Overview of PROSPECT and SAIL Model

Overview of PROSPECT and SAIL Model. Bo Qian bqian@umd.edu. 2nd IR/Microwave emissivity group meeting NOAA/NESDIS/STAR 2008.08.01. Introduction of PROSPECT. PROSPECT is a radiative transfer model that represents the optical properties of plant leaves from 400 nm to 2500 nm.

diem
Download Presentation

Overview of PROSPECT and SAIL Model

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Overview of PROSPECT and SAIL Model Bo Qian bqian@umd.edu 2nd IR/Microwave emissivity group meeting NOAA/NESDIS/STAR 2008.08.01

  2. Introduction of PROSPECT • PROSPECT is a radiative transfer model that represents the optical properties of plant leaves from 400 nm to 2500 nm. • The key parameters in the model are leaf structure parameter (N), chlorophyll a+b (Cab) and the equivalent water thickness (Cw) .

  3. PROSPECT- Leaf Optical Properties Spectra MODEL reflected +emitted depend on anatomical leaf structure and biochemical leaf composition absorbed transmitted+ emitted S.Jacquemoud and F.Baret, REMOTE SENS. ENVIRON.34:75-91(1990)

  4. Description of the PROSPECT model reflectance () Is Surface effects Elementary layer: n: refractive index K: global absorption coefficient Nidentical layers Hemispheric fluxes Global absorption: () transmittance (A.Olioso, S.Jacquemoud ,F.Baret, Adaptation of the leaf optical propertymodel PROSPECT to thermalinfrared,2006) Specificabsorptioncoefficients Content inabsorbingmaterial

  5. PROSPECT INPUTS Nleaf structure parameterCabchlorophyll a+b concentration (g.cm2)Cbpbrown pigment concentration (g.cm2)Cwequivalent water thickness (cm)Cmdry matter content (g.cm2) PROSPECT OUTPUTS R() T() –leaf reflectance – leaf transmittance

  6. Comparison of two different version 1998 version3.01 Cw=0 Cw=0.002 1995 version 2.01

  7. PROSPECT V3.01 outputs under Cw from 0.0 to 0.02 cm-1(0.0,0.0002, 0.0011, 0.0065, 0.0155, 0.02 cm-1) 0.02 0.0 0.0 0.02 N = 1.5, Cab = 50 g.cm2, Cdm = 0.005 g.cm2

  8. One question ? • Energy balance • Kirchhoff’s Law The emissivity of a body equals its absorptivity at thermal equilibrium So, absorptivity = emissivity ???

  9. Sensitivity of the Leaf Structure Parameter N • N=1~1.5 Albino maize leaf and monocotyledons with compact mesophyll • N=1.5~2.5 Dicotyledons by a spongy parenchyma with air cavities on the abaxial face • N>2.5 Senescent leaves with a disorganized internal structure

  10. Cw=0, N=1.0,1.5,2.0,2.5,3.0 3.0 2.5 2.0 1.5 1.0 Visible light Region

  11. Cw=0.02, N=1.0,1.5,2.0,2.5,3.0 3.0 2.5 2.0 1.5 1.0 400,690,1450,1950,2500

  12. Non-reasonable reasonable In fact, N=3 ,represents senescent leaves with disorganized structure, the Cw should be small even it is zero. So the combination given parameters of Cw=0.02 and N=3 should be non-reasonable. Relatively, the Cw=0.0 and N=3 will be a better choice.

  13. Questions: • The key point is how to determine the value of the combination inputs parameters. • What is the relationships between inputs parameters realistically? (N, Cab, Cw,Cm,Cbp) • Need in-situ data and satellites data validation

  14. Scattering by Arbitrarily Inclined Leaves-SAIL Model

  15. Introduction • The scattering and extinction coefficients of SAIL model are derived for the case of arbitrary leaf inclination angle and a random leaf azimuth distribution. • SAIL Model includes the G.H.Suits uniform model.

  16. Canopy Layer Morphology Characteristics The idealized morphology of a canopy layer assumed for the SAIL Model is given as following: • The layer is horizontal and infinitely extended • The only canopy components are small and flat leaves • The layer is homogenous

  17. SAIL model (Verhoef 1984-1985) sun bi-directional reflectance directional-hemispherical reflectance plant canopy absorption of directionalincoming radiation soil surface

  18. LAI mean leaf angle (θl) leaf reflectance (ρl) leaf transmittance (τl) soil reflectance (ρs) geometry of observation Sun position SAIL Model parameters Inputs • spectral reflectances • absorption of solar radiation Outputs

  19. W.VERHOEF, (1984),Remote sensing of Environment,16:15-141 Suits Model SAIL Model H=1.000 V=1.571 Bidirectional reflectance profiles in the green(550nm)

  20. W.VERHOEF, (1984),Remote sensing of Environment,16:15-141 Suits Model SAIL Model H=1.000 V=1.571 Bidirectional reflectance profiles in the near infrared

  21. Conclusions • The SAIL Model is an improved version of Suits’s canopy reflectance model • The extinction and scattering coefficients in the Suits’s Model are calculated on the basis of a given LAI and leaf inclination distribution • The calculation of canopy reflectance is the same both models, the uniform Suits model is included as a special case

  22. Next to do • As a very important aspect is try to understand how to exactly determine the inputs parameters for these two models • Understand the optical parameters calculation and details theory in the model

More Related