摘要
A new model for light-absorption and alhedo of a vegetation cover combines principles of geometric optics and radiative transfer.It relies on the gap probabilities and path length distributions to model the penetration of the irradiance from a parailel source and the single and multiple scattering of that irradi- ance.The model is applied to the vegetation covers of the discrete plant crowns that are randomly centred both on the plane and within a layer of variable thickness(from h_1 to h_2)above it.Crowns assume a spheroi- dal shape with an arbitrary height to width ratio(B/R).Geometric optics easily models the irradianee that penetrates the vegetation cover directly,and is scattered by the soil,and exist without further scattering by the vegetation.Within a plant crown,the probability of scattering is a negative exponential function of path length.Within crown scattering provides the source for the singly scattered radiation,which provides the source for double scattering,and then higher order pairs of scattering are solved successively by a convolution- like funaion.Early validations using data from a conifer stand near Howland,Maine of USA show reasonable agreement between the modeled and observed albedo.
A new model for light-absorption and alhedo of a vegetation cover combines principles ofgeometric optics and radiative transfer.It relies on the gap probabilities and path length distributions to modelthe penetration of the irradiance from a parailel source and the single and multiple scattering of that irradi-ance.The model is applied to the vegetation covers of the discrete plant crowns that are randomly centredboth on the plane and within a layer of variable thickness（from h<sub>1</sub> to h<sub>2</sub>）above it.Crowns assume a spheroi-dal shape with an arbitrary height to width ratio（B/R）.Geometric optics easily models the irradianee thatpenetrates the vegetation cover directly,and is scattered by the soil,and exist without further scattering by thevegetation.Within a plant crown,the probability of scattering is a negative exponential function of pathlength.Within crown scattering provides the source for the singly scattered radiation,which provides thesource for double scattering,and then higher order pairs of scattering are solved successively by a convolution-like funaion.Early validations using data from a conifer stand near Howland,Maine of USA show reasonableagreement between the modeled and observed albedo.
基金
the National Natural Science Foundation of China
the Director Grant of IRSA
NSF of USA
