Estimating land surface albedo in the HAPEX-Sahel southern super-site: Inversion of two BRDF models against multiple angle ASAS images

Abstract The provision of spatially and temporally disaggregated values of albedo is critical to an improved understanding of energy interactions at the Earth surface. Remotely sensed estimates of land surface albedo can best be obtained by inverting models of the Bidirectional Reflectance Distribution Function (BRDF) against bidirectional reflectance factor measurements sampled at different sensor view angles and solar illumination angles. This paper describes the preliminary results obtained using such an approach over the HAPEX-Sahel (Hydrological and Atmospheric Pilot Experiment) southern super-site in Niger. Two BRDF models, one empirical (modified-Walthall) and one semi-empirical (a linear kernel-driven model, employing isotropic, geometric and volume scattering kernels), are inverted analytically against each pixel in a set of co-registered multispectral images acquired by NASA's Advanced Solid-state Array Spectroradiometer (ASAS). The paper describes the methods used to register these images to sub-pixel accuracy, to perform radiometric and first-order atmospheric correction of the data, and to invert the BRDF model against the pre-processed image data to yield spatially referenced estimates of the model parameters and angularly integrated terms related to albedo. Spatial patterns, closely related to variations in land cover type, are clearly evident in these data. It is shown that, in this instance, the simple empirical model provides a better fit to the measured data, particularly at red and near-infrared wavelengths. The poorer performance of the semi-empirical model at this particular study site is discussed in terms of the assumptions that the model makes about energy interaction with the land surface. The impacts of changes in the projected instantaneous field-of-view as a function of sensor view angle and of residual image-to-image mis-registration on the derived BRDF model parameters and estimated albedo values are also examined.

[1]  A. Kuusk,et al.  A reflectance model for the homogeneous plant canopy and its inversion , 1989 .

[2]  N. Goel Models of vegetation canopy reflectance and their use in estimation of biophysical parameters from reflectance data , 1988 .

[3]  A. Strahler,et al.  Bidirectional reflectance modeling of data from vegetation obtained in the Changchun Solar Simulation Laboratory , 1995, 1995 International Geoscience and Remote Sensing Symposium, IGARSS '95. Quantitative Remote Sensing for Science and Applications.

[4]  S KimesD,et al.  直下方向及び方向性反射データを用いた地表からの半球状スペクトル反射(アルベド)の抽出 , 1987 .

[5]  Alan H. Strahler,et al.  An analytic BRDF model of canopy radiative transfer and its inversion , 1993, IEEE Trans. Geosci. Remote. Sens..

[6]  Darrel L. Williams,et al.  An off-nadir-pointing imaging spectroradiometer for terrestrial ecosystem studies , 1991, IEEE Trans. Geosci. Remote. Sens..

[7]  C. Tucker,et al.  Invertibility of a 1-D discrete ordinates canopy reflectance model , 1994 .

[8]  A. Strahler,et al.  Retrieval of surface BRDF from multiangle remotely sensed data , 1994 .

[9]  V. Salomonson,et al.  MODIS: advanced facility instrument for studies of the Earth as a system , 1989 .

[10]  J. Roujean,et al.  A bidirectional reflectance model of the Earth's surface for the correction of remote sensing data , 1992 .

[11]  H. Rahman,et al.  Coupled surface-atmosphere reflectance (CSAR) model: 2. Semiempirical surface model usable with NOAA advanced very high resolution radiometer data , 1993 .

[12]  R. Myneni,et al.  A review on the theory of photon transport in leaf canopies , 1989 .

[13]  P. Lewis,et al.  The utility of kernel-driven BRDF models in global BRDF and albedo studies , 1995, 1995 International Geoscience and Remote Sensing Symposium, IGARSS '95. Quantitative Remote Sensing for Science and Applications.

[14]  David J. Diner,et al.  A multiangle imaging spectroradiometer for terrestrial remote sensing from the earth observing system , 1991, Int. J. Imaging Syst. Technol..

[15]  Craig S. T. Daughtry,et al.  Surface albedo from bidirectional reflectance , 1991 .

[16]  D. Kimes Dynamics of directional reflectance factor distributions for vegetation canopies. , 1983, Applied optics.

[17]  G. Campbell,et al.  Simple equation to approximate the bidirectional reflectance from vegetative canopies and bare soil surfaces. , 1985, Applied optics.

[18]  Bernard Pinty,et al.  Extracting information on surface properties from bidirectional reflectance measurements , 1991 .

[19]  Bernard Pinty,et al.  The effect of surface anisotropy and viewing geometry on the estimation of NDVI from AVHRR , 1995 .

[20]  J. Muller,et al.  Terrestrial remote sensing science and algorithms planned for EOS/MODIS , 1994 .

[21]  P. J. Camillo,et al.  A canopy reflectance model based on an analytical solution to the multiple scattering equation , 1987 .

[22]  J-P Muller,et al.  Automatic Seed Point Generation For Stereo Matching And Multi-image Registration , 1991, [Proceedings] IGARSS'91 Remote Sensing: Global Monitoring for Earth Management.

[23]  Piers J. Sellers,et al.  A Global Climatology of Albedo, Roughness Length and Stomatal Resistance for Atmospheric General Circulation Models as Represented by the Simple Biosphere Model (SiB) , 1989 .

[24]  J-P Muller,et al.  An automated system for sub-pixel correction and geocoding of multi-spectral and multi-look aerial imagery , 1992 .

[25]  Donald W. Deering,et al.  A simple analytical function for bidirectional reflectance , 1992 .

[26]  Piers J. Sellers,et al.  Inferring hemispherical reflectance of the earth's surface for global energy budgets from remotely sensed nadir or directional radiance values , 1985 .

[27]  J. Muller,et al.  Sampling the surface bidirectional reflectance distribution function (BRDF): 1. evaluation of current and future satellite sensors , 1994 .

[28]  E. Vermote,et al.  Second Simulation Of The Satellite Signal In The Solar Spectrum - 6s Code , 1990, 10th Annual International Symposium on Geoscience and Remote Sensing.

[29]  R. Dickinson,et al.  A physical model of the bidirectional reflectance of vegetation canopies: 2. Inversion and validation , 1990 .

[30]  J. Ross The radiation regime and architecture of plant stands , 1981, Tasks for vegetation sciences 3.

[31]  Philip Lewis,et al.  Precise geometric registration of ASAS airborne data for land surface BRDF studies , 1994, Proceedings of IGARSS '94 - 1994 IEEE International Geoscience and Remote Sensing Symposium.

[32]  J. S. Wallace,et al.  Measurements of albedo variation over natural vegetation in the sahel , 1994 .

[33]  F. E. Nicodemus,et al.  Geometrical considerations and nomenclature for reflectance , 1977 .

[34]  A. Marshak,et al.  Calculation of canopy bidirectional reflectance using the Monte Carlo method , 1988 .

[35]  A. Strahler,et al.  On the derivation of kernels for kernel‐driven models of bidirectional reflectance , 1995 .

[36]  A. Henderson‐sellers,et al.  A global archive of land cover and soils data for use in general circulation climate models , 1985 .

[37]  R. Dickinson,et al.  A physical model for predicting bidirectional reflectances over bare soil , 1989 .

[38]  David J. Diner,et al.  Extraction of spectral hemispherical reflectance (albedo) of surfaces from nadir and directional reflectance data , 1987 .

[39]  Ann Henderson-Sellers,et al.  Surface albedo data for climatic modeling , 1983 .

[40]  B. Pinty,et al.  A physical model of the bidirectional reflectance of vegetation canopies , 1990 .