A Versatile Two-Stream Model for Retrieving Surface Spectral Albedos
| Li, Zhanqing | University of Maryland |
| Barker, Howard | Meteorological Service of Canada |
| Trishchenko, Alexander | Canada Centre for Remote Sensing |
Surface spectral albedo (SSA) has numerous applications in climate and environmental studies. Given that ground-based observations of SSA are very limited to small areas, space-borne remote sensing has been a primary means of acquiring SSA on large or global scales. To date, many satellite sensors measure reflectances in different spectral regions from which values of SSA can be inferred. Inversion algorithms range from simple linear relationships to complex full-fledged radiative transfer models. Often, algorithms were designed for application to a particular sensor or spectral band. In this study, we propose a more versatile parameterised algorithm that can be used for estimating SSA from satellite measured spectral albedos at the top of the atmosphere (TOA). The algorithm was developed based on a two-layer atmospheric model. Monochromatic and band-mean transmittances due to various absorbing species are accounted for. The reflectance and transmittance for direct and diffuse radiation in the second layer are determined by the generalised 2-stream solutions. Except for the parameterisation coefficients that vary with satellite sensor’s bandpass and spectral response function, the framework of the inversion model is applicable to any sensor or spectral region. The model is tested by applying to results from full-fledged radiative transfer simulations for a wide range of conditions for various satellite sensors and spectral bands. The complexity and accuracy of the model are intermediate relative to what are currently used.
This poster will be displayed at the ARM Science Team Meeting.