The aim of the UJCC (UK-Japan Climate Collaboration) project is to exploit the power of the Earth Simulator to produce world-leading climate simulations. The enhanced resolution models will allow unprecedented fidelity of simulation, and allow many emergent phenomena to be resolved. The science of the project will then be to understand how the increased resolution changes the large scale mean climate, consider whether the emergent processes are therefore essential to produce reliable climate models, and consider if these processes can be parameterised in lower resolution models, or if their importance is enough to drive model resolution to increase.

The UK-Japan Climate Collaboration (UJCC) officially started in 2005. UK scientists, residing in Japan for the duration of this three-year project, have successfully ported the Hadley Centre's current climate model, HadGEM, to the Earth Simulator supercomputer, one of the most powerful on Earth. After developing a range of high-resolution model versions, UJCC scientists have performed climate simulations with unprecedented detail, enabling the study of important processes, such as ENSO, and of climate extremes, such as cyclones, typhoons, hurricanes.

The project is a joint project between the Hadley Centre (DEFRA) and the NCAS-CGAM (Centre for Global Atmospheric Modelling) at the University of Reading.

Access to UJCC data at the BADC is currently restricted to:

• UJCC investigators
• UK-HiGEM investigators
• Met Office staff

Access to the UJCC data sets is available via the UJCC data browser directory . Alternatively you can ftp the data from ftp.ceda.ac.uk.

UJCC is making use of a broad group of models in order to systematically explore the role and value of resolution in climate system research. All the UJCC models have as their baseline science the initial reference HadGEM1a models used at the Hadley Centre. These build on the IPCC AR4 version of the model, and include various small improvements to the science and fixing of known problems. More details of HadGEM1a can be found here (this link is restricted to those with HiGEM privileges).

The UJCC data archived at the BADC are 30 year simulations from models at the following resolutions:

• N96 Atmosphere (1.25 lat x 1.875 lon), 1 degree ocean (HadGEM1a)
• N96 Atmosphere (1.25 lat x 1.875 lon), 1/3 degree ocean
• N144 Atmosphere (0.83 lat x 1.25 lon), 1 degree ocean
• N144 Atmosphere (0.83 lat x 1.25 lon), 1/3 degree ocean (HiGEM)

Simulations from the Nihon-UK Global Environmental Model (NUGEM) will also be archived at the BADC. NUGEM is a version of HadGEM1a run at very high N216 resolution (0.83 lat x 0.56 lon, corresponding to ~60 km in mid-latitudes). The BADC will be archiving:

• NUGAM Atmosphere only version of NUGEM
• NUGEM Coupled atmosphere and ocean

The BADC have provided a list of the simulations that make up the UJCC datset matrix in the BADC archive. A comprehensive overview of the matrix of UJCC climate models can be found here.

The current status of the UJCC dataset at the BADC can be found here.

We have now launched a web page showing the status of the current UJCC-HiGEM simulation. This service displays the evolution of certain key parameters including net top of atmosphere radiation flux, global mean sea surface and surface temperature and ocean salinity. The North Atlantic Oscillation and Nino-3 indices are also shown. These plots are updated as new data from the UJCC-HiGEM simulation arrives at the BADC.

Data file format
All UJCC data are held as 64 bit UM pp files.

Software
Software is available to manipulate and view the data. xconv provides an easy to use point and click interface to the data. convsh provides a subset of the functionality of xconv, but in a scriptable form, so it can be used to automate some common data processing tasks. Jeff Cole at CGAM Reading, who developed both xconv and convsh, provides some example uses of convsh.

• UJCC
• UK HiGEM
• Earth Simulator Center
• NCAS CGAM
• Frontier Research Center for Global Change (FRCGC-Japan)
• University of Tokyo - Center for Climate System Research (CCSR-Tokyo)

• The UJCC Principal Investigators in the UK are Pier Luigi Vidale (University of Reading) and Malcolm Roberts (Hadley Centre, Met Office).
• General queries about these pages and access to the data should be directed to the BADC help desk. Your query should be answered within one working day. When follow-up work is required, the BADC support will carry out the work as quickly and efficiently as possible, and in any case, the user will be kept informed of progress.