Abstract
The CNRM-Cerfacs Climate Prediction System (C3PS) is a new research
modeling tool for performing climate reanalyses and
seasonal-to-multiannual predictions for a wide array of earth system
variables. C3PS is based on the CNRM-ESM2-1 model including interactive
aerosols and stratospheric chemistry schemes as well as terrestrial and
marine biogeochemistry enabling a comprehensive representation of the
global carbon cycle. C3PS operates through a seamless coupled
initialization for the atmosphere, land, ocean, sea ice and
biogeochemistry components that allows a continuum of predictions across
seasonal to interannual time-scales. C3PS has also contributed to the
Decadal Climate Prediction Project (DCPP-A) as part of the sixth Coupled
Model Intercomparison Project (CMIP6).
Here we describe
the main characteristics of this novel earth system-based prediction
platform, including the methodological steps for obtaining initial
states to produce forecasts. We evaluate the entire C3PS initialisation
procedure with the most up-to-date observations and reanalysis over
1960-2021, and we discuss the overall performance of the system in the
light of the lessons learnt from previous and actual prediction
platforms. Regarding the forecast skill, C3PS exhibits comparable
seasonal predictive skill to other systems. At the decadal scale, C3PS
shows significant predictive skill in surface temperature during the
first two years after initialisation in several regions of the world.
C3PS also exhibits potential predictive skill in net primary production
and carbon fluxes several years in advance. This expands the possibility
of applications of forecasting systems, such as the possibility of
performing multi-annual predictions of marine ecosystems and carbon
cycle.