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Third Radiation Transfer Model Intercomparison (RAMI) exercise: Documenting progress in canopy reflectance models

Widlowski, JL; Taberner, M; Pinty, B; Bruniquel-Pinel, V; Disney, M; Fernandes, R; Gastellu-Etchegorry, JP; ... Xie, D; + view all (2007) Third Radiation Transfer Model Intercomparison (RAMI) exercise: Documenting progress in canopy reflectance models. Journal of Geophysical Research - Atmospheres , 112 (D9) , Article D09111. 10.1029/2006JD007821. Green open access

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Abstract

The Radiation Transfer Model Intercomparison ( RAMI) initiative benchmarks canopy reflectance models under well-controlled experimental conditions. Launched for the first time in 1999, this triennial community exercise encourages the systematic evaluation of canopy reflectance models on a voluntary basis. The first phase of RAMI focused on documenting the spread among radiative transfer (RT) simulations over a small set of primarily 1-D canopies. The second phase expanded the scope to include structurally complex 3-D plant architectures with and without background topography. Here sometimes significant discrepancies were noted which effectively prevented the definition of a reliable "surrogate truth,'' over heterogeneous vegetation canopies, against which other RT models could then be compared. The present paper documents the outcome of the third phase of RAMI, highlighting both the significant progress that has been made in terms of model agreement since RAMI-2 and the capability of/need for RT models to accurately reproduce local estimates of radiative quantities under conditions that are reminiscent of in situ measurements. Our assessment of the self-consistency and the relative and absolute performance of 3-D Monte Carlo models in RAMI-3 supports their usage in the generation of a "surrogate truth'' for all RAMI test cases. This development then leads ( 1) to the presentation of the "RAMI Online Model Checker'' (ROMC), an open-access web-based interface to evaluate RT models automatically, and ( 2) to a reassessment of the role, scope, and opportunities of the RAMI project in the future.

Type: Article
Title: Third Radiation Transfer Model Intercomparison (RAMI) exercise: Documenting progress in canopy reflectance models
Open access status: An open access version is available from UCL Discovery
DOI: 10.1029/2006JD007821
Publisher version: http://dx.doi.org/10.1029/2006JD007821
Language: English
Additional information: Copyright 2007 by the American Geophysical Union
Keywords: Digital hemispherical photography, Vegetation canopies, Leaf orientation, Solar-radiation, Plant canopies, Scattering, Project, Surface, Validation, Absorption
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL SLASH
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Geography
URI: https://discovery.ucl.ac.uk/id/eprint/10998
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