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Support Address: support@nsc.liu.se |
Paleo simulations with climate models
AbstractClimate model EC-Earth has been applied for producing historic simulations (e.g. 1850 to 2005 with known climate forcings such as greenhouse gas, volcanic, aerosol etc.) and future projections with different greenhouse gas scenarios (e.g., RCP45, RCP85 etc.). These experiments follow the CMIP5 protocol and the results have been reported in recent released IPCC Fifth Assessment Report. Most of the CMIP5 modeling groups have provided both the paleo simulations together with historic and future simulations, in order to show a systemic picture of climate variation along the time. However, the EC-Earth has not been used for paleo climate modeling yet. We know the climate models are built from the knowledge of present day and the physical parameterizations are based on present-day observation. But we don’t know if such model is valid for another unknown climate condition, i.e., the future and the past. Fortunately, natural archives such as tree-ring, ice-core, stalagmite etc., have recorded the past climate information and thus it is possible to validate the climate model for other climate conditions that differ from today. If the model is well tested for past climate, we will have more confidence for its ability to project the future climate. Being a new paleo-climate modeling group supported by the Bolin Centre for Climate Research in Stockholm University, we aim to perform paleo simulations with the latest version of EC-Earth. The first step is to follow the PMIP (Paleoclimate modeling intercomparison Project) protocols. The standard PMIP simulations include the time slice simulations for Mid-Holocene (6000 years before present) and Last Glacier Maximum (21,000 years before present), as well as a transient simulation for last millennium (850 AD to 1850 AD). The model output will be provided to the whole climate research community. Later we will run more specified experiments according to new developed scientific questions. At present the planned feasible simulations include two spin-up simulations (each about 500-800 years, depends on the steady state of ocean), five equilibrium simulations (each 500 years), at least two last millennium transient simulations (each 1000 years). Right now there are three scientists are setting-up and running these simulations. We are implementing the important physical processes such as orbital forcing in the model, as well as modifying the topography, ice sheet etc. for different past period. Besides the EC-Earth we also use other climate models such as CESM, CAM-iso, LOVECLIM for other projects. |
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