Natural carbon dioxide exchanges in the ECMWF Integrated Forecasting System: Implementation and offline validation

TitleNatural carbon dioxide exchanges in the ECMWF Integrated Forecasting System: Implementation and offline validation
Publication TypeMiscellaneous
Year of Publication2012
AuthorsBoussetta, S, Balsamo, G, Beljaars, ACM, A. Panareda, A, Calvet, J-C, Jacobs, C, van den Hurk, BJJ, Viterbo, P, Lafont, S, Dutra, E, Jarlan, L, Balzarolo, M, Papale, D, van der Werf, G
Secondary TitleTechnical Memorandum
Number675
Abstract

A carbon module has been added to the land surface model of the European Centre for Medium-Range Weather Forecasts (ECMWF) in order to simulate the photosynthesis processes fixing carbon dioxide into the biomass (the gross primary production) and the release of carbon dioxide via land biogenic processes (ecosystem respiration). This land carbon parameterization, integrated with the Hydrology-Tiled ECMWF Scheme for Surface Exchange over Land (HTESSEL), benefits from accurate simulations of soil moisture and introduces the capability of interacting with atmospheric carbon transport models by providing a biospheric CO2 flux (the Net Ecosystem Exchange NEE) as surface boundary condition. A description of the new carbon-based land surface scheme is provided here, together with its optimization and extensive verification based on field site experiments representing different types of vegetation and climate regimes. In areas where field-sites observations are not available, inter-comparison with well established and widely used NEE products are presented and discussed. The key features and the limitations of the model are evaluated in offline simulations driven by realistic meteorological forcing. In addition, global land surface carbon fluxes are compared with similar outputs from other state-of-the-art carbon models both in offline and in atmospheric-coupled simulations within a global transport model, showing an improved description of the interannual variability of atmospheric CO2 concentrations.