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Peter R Gent - One of the best experts on this subject based on the ideXlab platform.

  • the community earth System Model a framework for collaborative research
    Bulletin of the American Meteorological Society, 2013
    Co-Authors: James W Hurrell, Peter R Gent, Marika M Holland, Steven J Ghan, Jennifer E Kay, Paul J Kushner, Jeanfrancois Lamarque, William G Large, David M Lawrence, Keith Lindsay
    Abstract:

    The Community Earth System Model (CESM) is a flexible and extensible community tool used to investigate a diverse set of Earth System interactions across multiple time and space scales. This global coupled Model significantly extends its predecessor, the Community Climate System Model, by incorporating new Earth System simulation capabilities. These comprise the ability to simulate biogeochemical cycles, including those of carbon and nitrogen, a variety of atmospheric chemistry options, the Greenland Ice Sheet, and an atmosphere that extends to the lower thermosphere. These and other new Model capabilities are enabling investigations into a wide range of pressing scientific questions, providing new foresight into possible future climates and increasing our collective knowledge about the behavior and interactions of the Earth System. Simulations with numerous configurations of the CESM have been provided to phase 5 of the Coupled Model Intercomparison Project (CMIP5) and are being analyzed by the broad com...

  • the community climate System Model version 4
    Journal of Climate, 2011
    Co-Authors: Peter R Gent, Marika M Holland, David M Lawrence, Gokhan Danabasoglu, Leo J Donner, Elizabeth C Hunke, Steve R Jayne, Richard Neale, Philip J Rasch, Mariana Vertenstein
    Abstract:

    AbstractThe fourth version of the Community Climate System Model (CCSM4) was recently completed and released to the climate community. This paper describes developments to all CCSM components, and documents fully coupled preindustrial control runs compared to the previous version, CCSM3. Using the standard atmosphere and land resolution of 1° results in the sea surface temperature biases in the major upwelling regions being comparable to the 1.4°-resolution CCSM3. Two changes to the deep convection scheme in the atmosphere component result in CCSM4 producing El Nino–Southern Oscillation variability with a much more realistic frequency distribution than in CCSM3, although the amplitude is too large compared to observations. These changes also improve the Madden–Julian oscillation and the frequency distribution of tropical precipitation. A new overflow parameterization in the ocean component leads to an improved simulation of the Gulf Stream path and the North Atlantic Ocean meridional overturning circulati...

  • the community climate System Model version 2
    Journal of Climate, 2004
    Co-Authors: J T Kiehl, Peter R Gent
    Abstract:

    Abstract The Community Climate System Model, version 2 (CCSM2) is briefly described. A 1000-yr control simulation of the present day climate has been completed without flux adjustments. Minor modifications were made at year 350, which included all five components using the same physical constants. There are very small trends in the upper-ocean, sea ice, atmosphere, and land fields after year 150 of the control simulation. The deep ocean has small but significant trends; however, these are not large enough that the control simulation could not be continued much further. The equilibrium climate sensitivity of CCSM2 is 2.2 K, which is slightly larger than the Climate System Model, version 1 (CSM1) value of 2.0 K. Several aspects of the control simulation's mean climate and interannual variability are described, and good and bad properties of the control simulation are documented. In particular, several aspects of the simulation, especially in the Arctic region, are much improved over those obtained in CSM1. ...

  • the community climate System Model
    Bulletin of the American Meteorological Society, 2001
    Co-Authors: Maurice L Blackmon, J T Kiehl, Peter R Gent, Byron A Boville, Frank O Bryan, Robert E Dickinson, Richard E Moritz, David A Randall, J Shukla, Susan Solomon
    Abstract:

    Abstract The Community Climate System Model (CCSM) has been created to represent the principal components of the climate System and their interactions. Development and applications of the Model are carried out by the U.S. climate research community, thus taking advantage of both wide intellectual participation and computing capabilities beyond those available to most individual U.S. institutions. This article outlines the history of the CCSM, its current capabilities, and plans for its future development and applications, with the goal of providing a summary useful to present and future users. The initial version of the CCSM included atmosphere and ocean general circulation Models, a land surface Model that was grafted onto the atmosphere Model, a sea–ice Model, and a "flux coupler" that facilitates information exchanges among the component Models with their differing grids. This version of the Model produced a successful 300–yr simulation of the current climate without artificial flux adjustments. The mo...

  • the ncar climate System Model version one
    Journal of Climate, 1998
    Co-Authors: Byron A Boville, Peter R Gent
    Abstract:

    The NCAR Climate System Model, version one, is described. The spinup procedure prior to a fully coupled integration is discussed. The fully coupled Model has been run for 300 yr with no surface flux corrections in momentum, heat, or freshwater. There is virtually no trend in the surface temperatures over the 300 yr, although there are significant trends in other Model fields, especially in the deep ocean. The reasons for the successful integration with no surface temperature trend are discussed.

William D Collins - One of the best experts on this subject based on the ideXlab platform.

  • the integrated earth System Model version 1 formulation and functionality
    Geoscientific Model Development, 2015
    Co-Authors: William D Collins, Anthony Craig, John Truesdale, A V Di Vittorio, Andrew D Jones, Ben Bondlamberty, Katherine Calvin, Jae Edmonds, Allison M Thomson, Pralit Patel
    Abstract:

    Abstract. The integrated Earth System Model (iESM) has been developed as a new tool for projecting the joint human/climate System. The iESM is based upon coupling an integrated assessment Model (IAM) and an Earth System Model (ESM) into a common Modeling infrastructure. IAMs are the primary tool for describing the human–Earth System, including the sources of global greenhouse gases (GHGs) and short-lived species (SLS), land use and land cover change (LULCC), and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate System. The iESM project integrates the economic and human-dimension Modeling of an IAM and a fully coupled ESM within a single simulation System while maintaining the separability of each Model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore-omitted feedbacks between natural and societal drivers, we can improve scientific understanding of the human–Earth System dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural Systems. This paper describes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.

  • the community climate System Model version 3 ccsm3
    Journal of Climate, 2006
    Co-Authors: William D Collins, Maurice L Blackmon, Cecilia M Bitz, Gordon B Bonan, Christopher S Bretherton, James A Carton, Ping Chang, Scott C Doney, James J Hack, Tom Henderson
    Abstract:

    Abstract The Community Climate System Model version 3 (CCSM3) has recently been developed and released to the climate community. CCSM3 is a coupled climate Model with components representing the atmosphere, ocean, sea ice, and land surface connected by a flux coupler. CCSM3 is designed to produce realistic simulations over a wide range of spatial resolutions, enabling inexpensive simulations lasting several millennia or detailed studies of continental-scale dynamics, variability, and climate change. This paper will show results from the configuration used for climate-change simulations with a T85 grid for the atmosphere and land and a grid with approximately 1° resolution for the ocean and sea ice. The new System incorporates several significant improvements in the physical parameterizations. The enhancements in the Model physics are designed to reduce or eliminate several Systematic biases in the mean climate produced by previous editions of CCSM. These include new treatments of cloud processes, aerosol ...

Marcella Ruschi Mendes Saade - One of the best experts on this subject based on the ideXlab platform.

  • Investigating transparency regarding ecoinvent users’ System Model choices
    The International Journal of Life Cycle Assessment, 2019
    Co-Authors: Marcella Ruschi Mendes Saade, Alexander Passer, Sébastien Lasvaux, Maristela Gomes Da Silva, Vanessa Gomes, Cássia Maria Lie Ugaya, Guillaume Habert
    Abstract:

    PurposeLife cycle assessment (LCA) is a data-intensive methodology; therefore, experts usually focus collection efforts on a few activities, while generic data on remaining activities are taken from databases. Even though increased availability of databases has facilitated LCA takeoff, assuring data quality is fundamental to ensure meaningful results and reliable interpretation.MethodsEcoinvent has become a global reference for inventory data. Its current version released three impact partition Modeling options—the recycled content, “allocation at the point of substitution” (APOS), and consequential Models—whose adequate choice is crucial for yielding meaningful assessments. Tutorials and manuals describe the distribution algorithm that backs each System Model, to ground decision-making regarding the best fit to a study’s goals. We performed a Systematic literature review to investigate—within the papers published on the International Journal of LCA (IJLCA)—how transparently authors addressed the System Model choices.Results and discussionAbout 70% of LCA practitioners continued to use earlier versions of ecoinvent after version 3 was launched in 2013. The number of papers using versions 3.x only showed an increased growth trend 2 years later. Eighty-three papers actually adopted the newest version of the database. From those, only 29 papers clearly mentioned the adopted System Model. Our SLR also suggests a trend regarding authorship profile of LCA-related studies: the number of studies conducted by practitioners aware of the intricacies of sound Modeling of background and foreground data might have been surpassed by those conducted by non-LCA specialists who use LCA as a supporting tool for investigations in applied fields, and merely scratch the surface.ConclusionsOur results point to a need for a caveat : ecoinvent users must take time to understand the general concept behind each System Model and practice one of the most important actions when performing an LCA—state methodological choices clearly.

  • investigating transparency regarding ecoinvent users System Model choices
    International Journal of Life Cycle Assessment, 2019
    Co-Authors: Marcella Ruschi Mendes Saade, Maristela Gomes Da Silva, Vanessa Gomes, Sebastie Lasvau, Alexande Passe, Cássia Maria Lie Ugaya, Guillaume Habe
    Abstract:

    Life cycle assessment (LCA) is a data-intensive methodology; therefore, experts usually focus collection efforts on a few activities, while generic data on remaining activities are taken from databases. Even though increased availability of databases has facilitated LCA takeoff, assuring data quality is fundamental to ensure meaningful results and reliable interpretation. Ecoinvent has become a global reference for inventory data. Its current version released three impact partition Modeling options—the recycled content, “allocation at the point of substitution” (APOS), and consequential Models—whose adequate choice is crucial for yielding meaningful assessments. Tutorials and manuals describe the distribution algorithm that backs each System Model, to ground decision-making regarding the best fit to a study’s goals. We performed a Systematic literature review to investigate—within the papers published on the International Journal of LCA (IJLCA)—how transparently authors addressed the System Model choices. About 70% of LCA practitioners continued to use earlier versions of ecoinvent after version 3 was launched in 2013. The number of papers using versions 3.x only showed an increased growth trend 2 years later. Eighty-three papers actually adopted the newest version of the database. From those, only 29 papers clearly mentioned the adopted System Model. Our SLR also suggests a trend regarding authorship profile of LCA-related studies: the number of studies conducted by practitioners aware of the intricacies of sound Modeling of background and foreground data might have been surpassed by those conducted by non-LCA specialists who use LCA as a supporting tool for investigations in applied fields, and merely scratch the surface. Our results point to a need for a caveat: ecoinvent users must take time to understand the general concept behind each System Model and practice one of the most important actions when performing an LCA—state methodological choices clearly.

Christof Fetzer - One of the best experts on this subject based on the ideXlab platform.

  • The timed asynchronous distributed System Model
    IEEE Transactions on Parallel and Distributed Systems, 1999
    Co-Authors: Flaviu Cristian, Christof Fetzer
    Abstract:

    We propose a formal definition for the timed asynchronous distributed System Model. We present extensive measurements of actual message and process scheduling delays and hardware clock drifts. These measurements confirm that this Model adequately describes current distributed Systems such as a network of workstations. We also give an explanation of why practically needed services, such as consensus or leader election, which are not implementable in the time-free Model, are implementable in the timed asynchronous System Model.

  • the timed asynchronous distributed System Model
    IEEE International Symposium on Fault-Tolerant Computing, 1998
    Co-Authors: Flaviu Cristian, Christof Fetzer
    Abstract:

    We propose a formal definition for the timed asynchronous distributed System Model and we describe extensive measurements of actual message and process scheduling delays and hardware clock drifts that confirm that this Model adequately describes current distributed Systems built from networked workstations.

J T Kiehl - One of the best experts on this subject based on the ideXlab platform.

  • the community climate System Model version 2
    Journal of Climate, 2004
    Co-Authors: J T Kiehl, Peter R Gent
    Abstract:

    Abstract The Community Climate System Model, version 2 (CCSM2) is briefly described. A 1000-yr control simulation of the present day climate has been completed without flux adjustments. Minor modifications were made at year 350, which included all five components using the same physical constants. There are very small trends in the upper-ocean, sea ice, atmosphere, and land fields after year 150 of the control simulation. The deep ocean has small but significant trends; however, these are not large enough that the control simulation could not be continued much further. The equilibrium climate sensitivity of CCSM2 is 2.2 K, which is slightly larger than the Climate System Model, version 1 (CSM1) value of 2.0 K. Several aspects of the control simulation's mean climate and interannual variability are described, and good and bad properties of the control simulation are documented. In particular, several aspects of the simulation, especially in the Arctic region, are much improved over those obtained in CSM1. ...

  • the community climate System Model
    Bulletin of the American Meteorological Society, 2001
    Co-Authors: Maurice L Blackmon, J T Kiehl, Peter R Gent, Byron A Boville, Frank O Bryan, Robert E Dickinson, Richard E Moritz, David A Randall, J Shukla, Susan Solomon
    Abstract:

    Abstract The Community Climate System Model (CCSM) has been created to represent the principal components of the climate System and their interactions. Development and applications of the Model are carried out by the U.S. climate research community, thus taking advantage of both wide intellectual participation and computing capabilities beyond those available to most individual U.S. institutions. This article outlines the history of the CCSM, its current capabilities, and plans for its future development and applications, with the goal of providing a summary useful to present and future users. The initial version of the CCSM included atmosphere and ocean general circulation Models, a land surface Model that was grafted onto the atmosphere Model, a sea–ice Model, and a "flux coupler" that facilitates information exchanges among the component Models with their differing grids. This version of the Model produced a successful 300–yr simulation of the current climate without artificial flux adjustments. The mo...