Carbon-Land Model Intercomparison Project

Introduction

The purpose of this model-measurement intercomparison is to allow the international scientific community to evaluate the performance of biogeochemical models normally coupled to general circulation models (GCMs). Through a rigorous set of metrics, terrestrial models are scored based on their performance as compared to best-available site, field, and satellite observations. To this end, we encourage you to provide feedback on the experimental protocol, the metrics used to evaluate model performance, and the observational datasets available for use in the intercomparison.

In Experiment 1, biogeochemical land surface models are forced with an improved NCEP/NCAR reanalysis climate dataset. For these offline runs, the objective is to examine the ability of the models to reproduce surface carbon and energy fluxes at multiple sites, and to examine the influence of climate variability, prescribed atmospheric CO₂ concentrations, and land cover change on terrestrial carbon fluxes during the 20^th century, and specifically during the period for which the reanalysis data are available (1948-2004).

In Experiment 2, an active atmosphere model is used to couple energy flows between the atmosphere and the terrestrial biosphere. However, for both steady state and transient components of the experiment, atmospheric CO₂ follows a prescribed trajectory. The prescribed CO₂ is radiatively active and sea surface temperatures (SSTs) and ocean carbon fluxes are prescribed. The objective of these simulations is to examine the effect of a coupled biosphere-atmosphere on carbon fluxes and climate during the 20^th century.