Simplifying the Interaction of Land Surfaces with Radiation for Relating Remote Sensing Products to Climate Models

The amount of radiation absorbed in the photosynthetically active spectral region and the Leaf Area Index (LAI), are operationally available from Space Agencies. Climate models may benefit from these products provided their one dimensional radiation transfer schemes effectively represent, when appropriate, the three dimensional effects implied by the internal spatial variability of vegetation canopies, e.g., the leaf area density, at all scales and resolutions involved (typically from 1 to 100 kilometers). Failing to do so leads to inherent inconsistencies between the domain-averaged reflected and absorbed fluxes, and the implied Leaf Area Index. We propose a comprehensive approach which introduces a parameterization of the internal variability of the LAI in the 1-D representation of the radiation scheme, called a domain-averaged structure factor, and provides a description of the radiant fluxes fully consistent with the LAI specified by remote sensing. We take this opportunity to revisit and update the two-stream formulations implemented in climate models to accurately estimate the fractions of radiation absorbed separately by the vegetation canopy and the underlying surface.

PINTY Bernard;  LAVERGNE Thomas;  DICKINSON R.E.;  WIDLOWSKI Jean-Luc;  GOBRON Nadine;  VERSTRAETE Michel; 

2006-03-14

AMER GEOPHYSICAL UNION

JRC30843

https://publications.jrc.ec.europa.eu/repository/handle/JRC30843,