The tenth IMSC, Beijing, China, 2007 - International Meetings on ...

Matthew Collins
Hadley Centre, UK Metoffice
Myles Allen
University of Oxford
Climateprediction.net is a simulation project harnessing the power of idle PCs to
forecast the climate of the 21st century. In collaboration with the BBC, we asked volunteer
members of the public to download a climate model from the project website and to run it
locally on their PC. Each model forms a single member of a massive, perturbed physics
ensemble in the world's largest climate forecasting experiment. As well as discussing the
design of the experiment, we present some of our first results.
Statistical characterization of ensemble prediction systems: Application to the DEMETER
ensemble
Speaker: Jesús Fernández
Jesús Fernández
University of Cantabria
Cristina Primo
ECMWF
Antonio S. Cofiño
University of Cantabria
Jose M. Gutierrez
University of Cantabria
Miguel A. Rodriguez
Instituto de Fisica de Cantabria
A novel approach is presented to characterize and graphically represent the
spatiotemporal evolution of ensembles by means of a simple diagram. <strong>The</strong> study focuses on
the evolution of perturbations, defined as differences between each ensemble member and a
control member. <strong>The</strong> lognormal character of these perturbations suggests a characterization in
terms of the first two moments of the logarithmic transformed values (the log-perturbations).
On one hand, the mean is associated with the spatially-averaged exponential growth in time.
On the other hand, the variance accounts for the inhomogeneous and localized spatial growth
component.
We introduce the MVL (Mean-Variance of Logarithms) diagram to intuitively represent the
interplay and evolution of these two magnitudes. We show how this diagram uncovers useful
information about the spatiotemporal dynamics of the ensemble by appling it to the analysis of
the multimodel ensemble for seasonal forecasting developed in the EU-project DEMETER.
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