Geoscientific Model Development

CMIP5 represents the most ambitious and computer-intensive model inter-comparison project ever attempted. Integrating a new generation of Earth system models and sharing the model results with a broad community has brought with it many significant technical challenges, along with new community-wide efforts to provide the necessary software infrastructure. This special issue will focus on the software that supports the scientific enterprise for CMIP5, including: couplers and coupling frameworks for Earth system models; the Common Information Model and Controlled Vocabulary for describing models and data; The development of the Earth System Grid Federation; the development of new portals for providing data access to different end-user communities; the scholarly publishing of datasets, and studies of the software development and testing processes used for the CMIP5 models. We especially welcome papers that offer comparative studies of the software approaches taken by different groups, and lessons learnt from community efforts to create shareable software components and frameworks.

The climate record of the last millennium holds much promise for identifying the links between forcings and responses at the global, hemispheric and regional scale. The specifications for the Paleoclimate Model Intercomparison Project Phase III (PMIP3) and the Coupled Model Intercomparison Project Phase V (CMIP5) include controlled experiments for the period 850 to 1850 CE. The implementation of those experiments, the collation and development of the climate drivers over this period, and the assessment of the model responses are the focus of this special issue of Geoscientific Model Development.

The CSIRO Mk3L climate system model is a computationally-efficient coupled general circulation model, designed primarily for the study of climate variability and change on millennial timescales. The model distribution is freely available to the research community. This Special Issue allows the history and evolution of Mk3L to be comprehensively documented within a single issue of a journal. Papers are welcome which describe and evaluate components of the model, and which describe and evaluate subsequent enhancements to the modelling system. The issue is also intended for papers which document specific experiments, particularly those which contribute towards Model Intercomparison Projects.

In 2008 the temporal focus of the Palaeoclimate Modelling Intercomparison Project was expanded to include a model intercomparison for the mid-Pliocene warm period (ca. 3 Ma BP). This project is referred to as PlioMIP (Pliocene Model Intercomparison Project). Two experiments have been agreed upon and comprise phase 1 of the PlioMIP. The first (Experiment 1) will be performed with atmosphere-only GCMs. The second (Experiment 2) will utilise fully coupled ocean-atmosphere GCMs. In previous PMIP-style studies it has often been challenging to disentangle the effects of differences in model parametrisations and physics from differences in the methodology employed to implement the palaeo-boundary conditions. This special issue of Geoscientific Model Development provides a means for each participating group within PlioMIP to provide detailed information on how Pliocene boundary conditions were included within their models. This will help facilitate the identification of discrepancies between models at the intercomparison phase. The issue also provides a means for each group to provide basic climatology's from each PlioMIP experiment, ensuring that a minimum level of output is readily available for the intercomparison phase. Finally the issue includes two papers that describe in detail the experimental design and boundary conditions used for both PlioMIP Experiments 1 and 2.

FAMOUS is climate model based on the widely-used "HadCM3" atmosphere-ocean general circulation code, a version of the UK Met Office Unified Model. Run at a lower resolution than HadCM3 its computational requirements make it suitable for large ensembles and millennial-scale climate simulations. This ongoing Special Issue collects technical documentation and evaluations of the model climatology as FAMOUS is developed and coupled to models of other Earth system components.