Evaluating The Representation And Impact Of Convective Processes In The Ncars Community Climate System Model PDF Download
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Release | : 2008 |
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Download Evaluating the Representation and Impact of Convective Processes in the NCAR's Community Climate System Model Book in PDF, ePub and Kindle
Convection and clouds affect atmospheric temperature, moisture and wind fields through the heat of condensation and evaporation and through redistributions of heat, moisture and momentum. Individual clouds have a spatial scale of less than 10 km, much smaller than the grid size of several hundred kilometers used in climate models. Therefore the effects of clouds must be approximated in terms of variables that the model can resolve. Deriving such formulations for convection and clouds has been a major challenge for the climate modeling community due to the lack of observations of cloud and microphysical properties. The objective of our DOE CCPP project is to evaluate and improve the representation of convection schemes developed by PIs in the NCAR (National Center for Atmospheric Research) Community Climate System Model (CCSM) and study its impact on global climate simulations.
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Release | : 2008 |
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Download Final Report on Evaluating the Representation and Impact of Convective Processes in the NCAR Community Climate System Model Book in PDF, ePub and Kindle
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Release | : 2008 |
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Download Evaluating the Representation and Impact of Convective Processes in the NCAR{u2019}s Community Climate System Model Book in PDF, ePub and Kindle
Convection and clouds affect atmospheric temperature, moisture and wind fields through the heat of condensation and evaporation and through redistributions of heat, moisture and momentum. Individual clouds have a spatial scale of less than 10 km, much smaller than the grid size of several hundred kilometers used in climate models. Therefore the effects of clouds must be approximated in terms of variables that the model can resolve. Deriving such formulations for convection and clouds has been a major challenge for the climate modeling community due to the lack of observations of cloud and microphysical properties. The objective of our DOE CCPP project is to evaluate and improve the representation of convection schemes developed by PIs in the NCAR (National Center for Atmospheric Research) Community Climate System Model (CCSM) and study its impact on global climate simulations.
Author | : Division on Earth and Life Studies |
Publisher | : National Academies Press |
Total Pages | : 252 |
Release | : 2013-01-24 |
Genre | : Science |
ISBN | : 0309259770 |
Download A National Strategy for Advancing Climate Modeling Book in PDF, ePub and Kindle
As climate change has pushed climate patterns outside of historic norms, the need for detailed projections is growing across all sectors, including agriculture, insurance, and emergency preparedness planning. A National Strategy for Advancing Climate Modeling emphasizes the needs for climate models to evolve substantially in order to deliver climate projections at the scale and level of detail desired by decision makers, this report finds. Despite much recent progress in developing reliable climate models, there are still efficiencies to be gained across the large and diverse U.S. climate modeling community. Evolving to a more unified climate modeling enterprise-in particular by developing a common software infrastructure shared by all climate researchers and holding an annual climate modeling forum-could help speed progress. Throughout this report, several recommendations and guidelines are outlined to accelerate progress in climate modeling. The U.S. supports several climate models, each conceptually similar but with components assembled with slightly different software and data output standards. If all U.S. climate models employed a single software system, it could simplify testing and migration to new computing hardware, and allow scientists to compare and interchange climate model components, such as land surface or ocean models. A National Strategy for Advancing Climate Modeling recommends an annual U.S. climate modeling forum be held to help bring the nation's diverse modeling communities together with the users of climate data. This would provide climate model data users with an opportunity to learn more about the strengths and limitations of models and provide input to modelers on their needs and provide a venue for discussions of priorities for the national modeling enterprise, and bring disparate climate science communities together to design common modeling experiments. In addition, A National Strategy for Advancing Climate Modeling explains that U.S. climate modelers will need to address an expanding breadth of scientific problems while striving to make predictions and projections more accurate. Progress toward this goal can be made through a combination of increasing model resolution, advances in observations, improved model physics, and more complete representations of the Earth system. To address the computing needs of the climate modeling community, the report suggests a two-pronged approach that involves the continued use and upgrading of existing climate-dedicated computing resources at modeling centers, together with research on how to effectively exploit the more complex computer hardware systems expected over the next 10 to 20 years.
Author | : G. L. Potter |
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Total Pages | : 9 |
Release | : 2003 |
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Download EVALUATION OF AN IMPROVED CONVECTION TRIGGERING MECHANISM IN THE NCAR COMMUNITY ATMOSPHERE MODEL CAM2 UNDER CAPT FRAMEWORK. Book in PDF, ePub and Kindle
The problem that convection over land is overactive during warm-season daytime in the National Center for Atmospheric Research (NCAR) Community Atmosphere Model CAM2 and its previous version (CCM3) has been found both in its single-column model (SCM) simulations (Xie and Zhang 2000; Ghan et al. 2000; Xie et al. 2002) and in its full general circulation model (GCM) short-range weather forecasts (Phillips et al. 2003) and climate simulations (Dai and Trenberth 2003). These studies showed that this problem is closely related to the convection triggering mechanism used in its deep convection scheme (Zhang and McFarlane 1995), which assumes that convection is triggered whenever there is positive convective available potential energy (CAPE). The positive CAPE triggering mechanism initiates model convection too often during the day because of the strong diurnal variations in the surface isolation and the induced CAPE diurnal change over land in the warm season. To reduce the problem, Xie and Zhang (2000) introduced a dynamic constraint, i.e., a dynamic CAPE generation rate (DCAPE) determined by the large-scale advective tendencies of temperature and moisture, to control the onset of deep convection. They showed that positive DCAPE is closely associated with convection in observations and the dynamic constraint could largely reduce the effect of the strong diurnal variations in the surface fluxes on the initiation of convection. Using the SCM version of CCM3, which has the same deep convection scheme as CAM2, Xie and Zhang (2000) showed that considerable improvements can be obtained in the model simulation of precipitation and other thermodynamic fields when the dynamic constraint was applied to the model triggering function. However, the performance of the improved convection triggering mechanism in the full GCM has not been tested. In this study, we will test the improved convection trigger mechanism in CAM2 under the U.S. Department of Energy's Climate Change Prediction Program (CCPP)--Atmospheric Radiation Measurement Program (ARM) Parameterization Testbed (CAPT) framework, which provides a flexible environment for running climate models in Numerical Weather Prediction (NWP) mode. In comparison with testing physical parameterizations in climate simulations, the CAPT strategy uses more available observations and high-frequency NWP analyses to evaluate model performance in short-range weather forecasts. This allows specific parameterization deficiencies to be identified before the compensation of multiple errors masks the deficiencies, as can occur in model climate simulation. Another advantage of the CAPT approach is its capability to link model deficiencies directly with atmospheric processes through case studies using data collected from major field programs (e.g., ARM).
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Total Pages | : 20 |
Release | : 2002 |
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Download Land Processes in a High Resolution Community Climate Model with Sub-Grid Scale Parameterizations Final Report Book in PDF, ePub and Kindle
The characteristics of land important for climate are very heterogeneous, as are the key atmospheric inputs to land, i.e. precipitation and radiation. To adequately represent this heterogeneity, state-of-the-art climate models should represent atmospheric inputs to land, land properties, and the dynamical changes of land at the highest resolution accessible by climate models. The research funded under this project focused on the development of an alternative approach to this problem in which a sub-mesh is imposed on each atmospheric model grid square. This allows representation of the land climate dynamics at a higher resolution than that achievable in the global atmospheric models. The high spatial detail of the fine-mesh treatment provides not only a more accurate representation of land processes to the atmospheric model, but also the opportunity for direct downscaling of the surface climate. The proposed project continued the development and refinement of a high-resolution land surface model that is compatible for inclusion into the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM), a state-of-the-art atmospheric general circulation model (GCM) that is used for climate simulation and prediction.
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Total Pages | : 36 |
Release | : 2014 |
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ISBN | : 9789174479188 |
Download The Representation of Atmospheric Boundary Layer Processes in Global Climate Models Book in PDF, ePub and Kindle
Author | : Intergovernmental Panel on Climate Change. Working Group II. |
Publisher | : Cambridge University Press |
Total Pages | : 532 |
Release | : 1998 |
Genre | : Science |
ISBN | : 9780521634557 |
Download The Regional Impacts of Climate Change Book in PDF, ePub and Kindle
Cambridge, UK : Cambridge University Press, 1998.
Author | : Andrew Gettelman |
Publisher | : Springer |
Total Pages | : 282 |
Release | : 2016-04-09 |
Genre | : Technology & Engineering |
ISBN | : 3662489597 |
Download Demystifying Climate Models Book in PDF, ePub and Kindle
This book demystifies the models we use to simulate present and future climates, allowing readers to better understand how to use climate model results. In order to predict the future trajectory of the Earth’s climate, climate-system simulation models are necessary. When and how do we trust climate model predictions? The book offers a framework for answering this question. It provides readers with a basic primer on climate and climate change, and offers non-technical explanations for how climate models are constructed, why they are uncertain, and what level of confidence we should place in them. It presents current results and the key uncertainties concerning them. Uncertainty is not a weakness but understanding uncertainty is a strength and a key part of using any model, including climate models. Case studies of how climate model output has been used and how it might be used in the future are provided. The ultimate goal of this book is to promote a better understanding of the structure and uncertainties of climate models among users, including scientists, engineers and policymakers.
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Total Pages | : 88 |
Release | : 1961-05 |
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Download Bulletin of the Atomic Scientists Book in PDF, ePub and Kindle
The Bulletin of the Atomic Scientists is the premier public resource on scientific and technological developments that impact global security. Founded by Manhattan Project Scientists, the Bulletin's iconic "Doomsday Clock" stimulates solutions for a safer world.