Regionally aggregated, stitched and de‐drifted CMIP‐climate data, processed with netCDF‐SCM v2.0.0

The world's most complex climate models are currently running a range of experiments as part of the Sixth Coupled Model Intercomparison Project (CMIP6). Added to the output from the Fifth Coupled Model Intercomparison Project (CMIP5), the total data volume will be in the order of 20PB. Here, we present a dataset of annual, monthly, global, hemispheric and land/ocean means derived from a selection of experiments of key interest to climate data analysts and reduced complexity climate modellers. The derived dataset is a key part of validating, calibrating and developing reduced complexity climate models against the behaviour of more physically complete models. In addition to its use for reduced complexity climate modellers, we aim to make our data accessible to other research communities. We facilitate this in a number of ways. Firstly, given the focus on annual, monthly, global, hemispheric and land/ocean mean quantities, our dataset is orders of magnitude smaller than the source data and hence does not require specialized ‘big data’ expertise. Secondly, again because of its smaller size, we are able to offer our dataset in a text-based format, greatly reducing the computational expertise required to work with CMIP output. Thirdly, we enable data provenance and integrity control by tracking all source metadata and providing tools which check whether a dataset has been retracted, that is identified as erroneous. The resulting dataset is updated as new CMIP6 results become available and we provide a stable access point to allow automated downloads. Along with our accompanying website (cmip6.science.unimelb.edu.au), we believe this dataset provides a unique community resource, as well as allowing non-specialists to access CMIP data in a new, user-friendly way

Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5

We present the global general circulation model IPSL-CM5 developed to study the long-term response of the climate system to natural and anthropogenic forcings as part of the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). This model includes an interactive carbon cycle, a representation of tropospheric and stratospheric chemistry, and a comprehensive representation of aerosols. As it represents the principal dynamical, physical, and bio-geochemical processes relevant to the climate system, it may be referred to as an Earth System Model. However, the IPSL-CM5 model may be used in a multitude of configurations associated with different boundary conditions and with a range of complexities in terms of processes and interactions. This paper presents an overview of the different model components and explains how they were coupled and used to simulate historical climate changes over the past 150 years and different scenarios of future climate change. A single version of the IPSL-CM5 model (IPSL-CM5A-LR) was used to provide climate projections associated with different socio-economic scenarios, including the different Representative Concentration Pathways considered by CMIP5 and several scenarios from the Special Report on Emission Scenarios considered by CMIP3. Results suggest that the magnitude of global warming projections primarily depends on the socio-economic scenario considered, that there is potential for an aggressive mitigation policy to limit global warming to about two degrees, and that the behavior of some components of the climate system such as the Arctic sea ice and the Atlantic Meridional Overturning Circulation may change drastically by the end of the twenty-first century in the case of a no climate policy scenario. Although the magnitude of regional temperature and precipitation changes depends fairly linearly on the magnitude of the projected global warming (and thus on the scenario considered), the geographical pattern of these changes is strikingly similar for the different scenarios. The representation of atmospheric physical processes in the model is shown to strongly influence the simulated climate variability and both the magnitude and pattern of the projected climate changes

OPA 8.1 Tracer Model reference manual

The tracer transport model implemented in OPA deals with passive tracers, which are transported by but do not affect ocean circulation. These contrast with active tracers such as temperature and salinity that feedback on ocean dynamics. The tracer transport model computes the evolution of passive tracers either “on-line” along with the dynamics, or “off-line“ using fields of advection and diffusion that have been previously calculated and stored to disk. Passive tracers in the ocean are typically biogeochemical, biological or radioactive. They are transported by the oceanic circulation, but they may in nature also degrade or interact with one another. Typically, the associated "Source-Minus-Sink" (SMS) terms are also included in the transport equation and depend upon the application

OPA-9: French experiments on the Earth Simulator and Teraflop workbench timings

International audienc

The PRISM software framework and the OASIS coupler

The increasing complexity of Earth system models (ESMs) and computing facilities puts a heavy technical burden on the research teams active in climate modelling. PRISM provides the Earth System Modelling community with a forum to promote sharing of development, maintenance and support of standards and software tools used to assemble, run, and analyse ESMs based on state-of-the-art component models (ocean, atmosphere, land surface, etc..) developed in the different climate research centres in Europe and elsewhere. PRISM is organised as a distributed network of experts who contribute to five "PRISM Areas of Expertise" (PAE): 1) Code coupling and I/O, 2) Integration and modelling environments, 3) Data processing, visualisation and management, 4) Meta-data, and 5) Computing. For example, the PAE “Code coupling and I/O” develops and supports the OASIS coupler, a software allowing synchronized exchanges of coupling information between numerical codes representing different components of the climate system. OASIS successfully demonstrates shared software, capitalising about 25 person-years of mutual developments and fulfilling the coupling needs of about 15 climate research groups around the world

Changes in tropospheric aerosol and reactive gases burdens and concentrations under IPCC-AR5 emission scenarios for 1850-2100

International audienceTropospheric ozone and aerosols are major climate forcing agents but the quantification of their forcings are still highly uncertain. In the framework of the ACC-MIP, a global decadal dataset describing the emissions of aerosols and ozone precursors and consistent with those provided for long-lived GHG, was made available. It allowed chemistry-climate models to simulate the evolution of short-lived GHG over the historical period (1850-2005) and for 4 future projections (Representative Concentration Pathways). This work describes the results obtained with the LMDz-INCA model using these state-of-the-art emissions and considering past and future climate change trajectories in a General Circulation Model. These concentrations are currently used as forcing by the two French Earth system models (IPSL-CM5 and CNRM-CM5) to simulate the climate evolution in the CMIP5 framework. The variability and trends of the concentrations along with their relevance will be discussed. In parallel to these projections considering the anthropogenic emissions changes, a short insight on the potential impact of natural isoprene emission changes on ozone will be shown