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Topic: Climate model


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In the News (Fri 10 Jul 09)

  
  Climate model - Wikipedia, the free encyclopedia
Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice.
Alternatively, the zero-dimensional model may be expanded horizontally to consider the energy transported - ahem - horizontally in the atmosphere.
This model has the advantage of allowing a plausible dependence of albedo on temperature - the poles can be allowed to be icy and the equator warm - but the lack of true dynamics means that horizontal transports have to be specified.
en.wikipedia.org /wiki/Climate_model   (893 words)

  
 Global climate model - Wikipedia, the free encyclopedia
A simple general circulation model (SGCM), a minimal GCM, consists of a dynamical core, for example the primitive equations, energy input into the model, and energy dissipation in the form of scale-dependent friction, so that atmospheric waves with the highest wavenumbers are the ones most strongly attenuated.
A debate over how to reconcile climate model predictions that upper air (tropospheric) warming should be greater than surface warming, with observations some of which appeared to show otherwise [16] now appears to have been resolved in favour of the models, following revisions to the data: see satellite temperature record.
The global climate models used for climate projections are very similar in structure to (and often share computer code with) numerical models for weather prediction but are nonetheless logically distinct: see climate vs weather for details.
en.wikipedia.org /wiki/General_circulation_model   (2850 words)

  
 Climate Change 2001: The Scientific Basis
The model ranges for Bern-CC were obtained by combining different bounding assumptions about the behaviour of the CO fertilisation effect, the response of heterotrophic respiration to temperature and the turnover time of the ocean, thus approaching an upper bound on uncertainties in the carbon cycle.
Both models adopted a “reference case” with mid-range behaviour of the carbon cycle and climate sensitivity of 2.5°C. In contrast with the SAR, the results presented here are based on approximating the behaviour of spatially resolved process-based models in which CO and climate responses are not constrained by prior assumptions about the global carbon budget.
In addition to varying the climate sensitivity (1.5 to 4.5°C), parameters of the terrestrial and ocean components (strength of CO fertilisation, temperature response of NPP and heterotrophic respiration; ocean heat and DIC transport) were adjusted to mimic the ranges of CO and climate responses as shown by existing process-based models (Figure 3.10).
www.grida.no /climate/ipcc_tar/wg1/122.htm   (1323 words)

  
 Climate Change 2001: The Scientific Basis
The model was designed to work in flux adjusted mode and it is possible that the non-flux adjusted SST errors could have been reduced by relatively minor “tuning” of the model.
In this chapter, we assess climate models on the basis of their ability to simulate present and past climates.
Overall, differences have been seen in the climate change response of flux adjusted and equivalent non-flux adjusted models (Fanning and Weaver, 1997b; Gregory and Mitchell, 1997), but it is not clear whether the differences are due to the flux adjustment itself, or to the systematic errors in the non-flux adjusted model.
www.grida.no /climate/ipcc_tar/wg1/315.htm   (1275 words)

  
 CCCma: Models, The First Generation Coupled Global Climate Model (CGCM1)
The model uses heat and water flux adjustments obtained from uncoupled ocean and atmosphere model runs (of 10 years and 4000 years duration respectively), followed by an `adaption' procedure in which the flux adjustment fields are modified by a 14 year integration of the coupled model.
A multi-century control simulation with the coupled model has been performed using the present-day CO concentration to evaluate the stability of the coupled model's climate, and to compare the modelled climate and its variability to that observed.
In addition, the `technology' of coupling various model components is receiving considerable attention with new methods of `spinning up' the ocean model to equilibrium, reducing the `shock' the model components experience upon coupling, and minimizing or eliminating the requirement for flux adjustment.
www.cccma.bc.ec.gc.ca /models/cgcm1.shtml   (1416 words)

  
 Hadley Centre: Climate Models
Simple models of the climate system have been developed and used both to gain physical insight into major features of the behaviour of the climate system, and to produce climate projections for a range of assumptions about emissions of carbon dioxide and other greenhouse gases.
This type of model predicts changes in sea-surface temperatures and sea ice by treating the ocean as though it were a layer of water of constant depth (typically 50 metres), heat transports within the ocean being specified and remaining constant while climate changes.
The carbon cycle model is needed in order to capture several important climate feedbacks on carbon dioxide concentration, for instance fertilisation of plant growth by carbon dioxide and uptake or outgassing of carbon dioxide by the oceans.
www.met-office.gov.uk /research/hadleycentre/models/modeltypes.html   (939 words)

  
 NCAR Releases New Version of Premier Global Climate Model - News Release
NCAR developed the model in collaboration with researchers at universities and laboratories across the country, with funding from the National Science Foundation, the Department of Energy, the National Oceanic and Atmospheric Administration, and the National Aeronautics and Space Administration.
CCSM3 is one of the world's leading general-circulation climate models, which are extraordinarily sophisticated computer tools that incorporate phenomena ranging from the effect that volcanic eruptions have on temperature patterns to the impact of shifting sea ice on sunlight absorbed by the oceans.
Climate models work by solving mathematical formulas, which represent the chemical and physical processes that drive Earth's climate, for thousands of points in the atmosphere, oceans, sea ice, and land surface.
www.ucar.edu /news/releases/2004/ccsm.shtml   (797 words)

  
 Models, Models...
This map was derived from an NCAR model used to study the effects of land surfaces on climate and atmospheric chemistry.
To the initiated, they are known as "general circulation models" (defined) and their purpose in life is to simulate past, present and future climate.
One way to test the model, says Hurrell, is to ask it to model climate for a particular time, say 1990 to 1995, and then compare the model's output with what the climate was really like.
whyfiles.org /021climate/models.html   (794 words)

  
 MIT Integrated Global System Model
The current IGSM formulation includes an economic model for analysis of greenhouse and aerosol precursor gas emissions and mitigation proposals, a coupled model of atmospheric chemistry and climate, and models of terrestrial ecosystems.
To calculate atmospheric composition, the model of atmospheric chemistry includes analysis of the climate-relevant reactive gases and aerosols at urban scales, coupled to a model of the processing of exported pollutants from urban areas (plus the emissions from non-urban areas) at the regional to global scale.
A natural emissions model component is used to simulate the natural emissions from the terrestrial biosphere to the atmosphere.
web.mit.edu /globalchange/www/if.html   (771 words)

  
 NASA GISS: General Circulation Models   (Site not responding. Last check: 2007-11-05)
The GCMs are all Cartesian grid-point models which can be run at a variety of horizontal and vertical resolutions; e.g., 8°×10°, 4°×5°, or 2°×2.5° in the horizontal (latitude × longitude) and nine-layer, eighteen-layer, 23-layer, and 31-layer in the vertical.
Model II used a second-order scheme for the advection of momentum, temperature, and humidity, but a higher-order numerical scheme for advection of temperature and specific humidity has been incorporated into Model II' ("two-prime").
The new model includes the option of coupling to a variety of ocean models, up to and including fully dynamic three-dimensional (3D) ocean general circulation models (OGCMs) and the full incoporation into the model of a number of tracer subsystems including atmospheric chemistry and aerosol transport.
www.giss.nasa.gov /research/modeling/gcms.html   (330 words)

  
 Climate System Model
The purpose of this model is to provide a tool for you to build your intuition of how the climate system works, to explore how it responds to perturbations, and to examine how sensitive it is to the various feedbacks we have discussed in class.
In this model, all of the anthropogenic carbon release must be accounted for by either uptake by the biosphere or an increase in the amount of carbon in the atmosphere.
The first four plots (all in a line) are just to remind you of the exact nature of the climate model that you're working with and the values for the solar constant and other parameters that you have chosen.
www.atmos.washington.edu /honors_220/model/model_instructions.html   (1630 words)

  
 PNNL News and Publications
The model, created by researchers at the Department of Energy's Pacific Northwest National Laboratory, indicates the Northwest will have significantly warmer and wetter winters in 80 years unless carbon dioxide emissions are reduced greatly.
PNNL scientists begin by using a global climate model to determine the environmental influences in a specific region, such as the Northwest.
The laboratory's regional climate model incorporates environmental data from areas as small as one square kilometer.
www.pnl.gov /news/1999/climate.htm   (677 words)

  
 6 box climate model
The outgoing long-wavelength or infrared energy in this model is basically the difference between the energy emitted by the land and the atmosphere to space and the energy re-radiated to the land surface by the atmosphere.
Since this model has different latitude zones, there have to be flows between the reservoirs representing the transfer of heat from the equators to the poles, which is one of the major jobs of the atmospheric and oceanographic circulation.
Zone 6, in the model, has a difficult time staying cold and one possible explanation is that the heat diffusion coefficient should not be the same for this zone as for the rest of the globe.
www.carleton.edu /departments/geol/DaveSTELLA/climate/6box/6_box_climate_model.htm   (3738 words)

  
 NCAS-ACMSU: Research - UKCA Model
In the modelling for the 3rd assessment report of the IPCC, tropospheric chemistry modelling using HadCM3 was performed off-line from other components of the climate model.
There is clearly a case for combining the best aspects of these models in a framework to create a flexible model environment based on the UM with the added advantage of being accessible to more users in the research community than the current generation of models.
New aerosol observations and detailed model simulations highlight the importance of aerosol types that are not presently included in the current model; the most important being nitrate and secondary organic aerosol, the latter formed from biogenic and anthropogenic source gases.
www.atm.ch.cam.ac.uk /acmsu/research_ukca.html   (1122 words)

  
 ClimatePrediction.Net gateway   (Site not responding. Last check: 2007-11-05)
GCMs try to simulate as much as possible about the climate system: the incoming and outgoing radiation, the way the air moves, the way clouds form and precipitation falls, the way the ice sheets grow or shrink, etc. They are frequently (as in the model we use) coupled to a representation of the ocean.
This is sometimes avoided by using a simplified model called a "slab ocean", which effectively just represents the top 50m of the ocean, with none of the deep sea currents which can transport a huge amount of heat, albeit very very slowly.
Fluxes of heat, wind, and freshwater are passed between the ocean model and the atmosphere model at the ocean-atmosphere interface.
www.climateprediction.net /science/model-intro.php   (2857 words)

  
 History of the NCAR Community Climate Model
The use of one basic model for both forecasting and climate studies was also seen to have great potential scientific value since a major part of medium-range (one- to two-week) forecast error is due to the drift toward a model climate which differs from that of the atmosphere.
The resulting model code, designated CCM0B, was described in a series of technical notes which included a User's Guide [31], a description of model subroutines [39], a detailed description of the continuous algorithms [38], and circulation statistics from long January and July simulations [42].
The advantages of the community model concept, in which many scientists use the same basic model for a variety of scientific studies, were demonstrated in workshops held at NCAR in July 1985 [1], July 1987 [44], and July 1990 [45].
www.csm.ornl.gov /chammp/pccm2.1/doc/node2.html   (1400 words)

  
 Climate model predicts dramatic changes over next 100 years
Climate models are sophisticated computer codes that attempt to incorporate as many details about the complex workings of our environment as possible.
With their improvements over previous models, the team has been able to make several observations about the change in climate over the next century, particularly for the late century when greenhouse gas accumulation could have greater effect than, say, a decade from now.
The model, Diffenbaugh said, assumes that greenhouse gases will attain a concentration more than twice their current levels, but he said he is confident that the model's performance gives as accurate a picture of the future as we can hope for at the moment.
www.eurekalert.org /pub_releases/2005-10/pu-cmp101405.php   (1574 words)

  
 New observations and climate model data confirm recent warming of the tropical atmosphere
Until recently, climate modelers compared their simulations with temperatures from a single satellite dataset, which showed slight cooling of the tropical troposphere since 1979.
This region of the atmosphere is predicted to warm in climate model simulations that include observed increases in greenhouse gases.
The computer models analyzed in the Livermore study show that in the deep tropics, temperature changes in the troposphere are larger than at the surface.
www.eurekalert.org /pub_releases/2005-08/dlnl-noa081105.php   (502 words)

  
 Topographic Features Improve Climate Model Predictions
By adding topographic features to their hydrologic model, researchers at the University of Illinois can better assess the impact of climate variability and global warming on terrestrial systems such as stream ecology, water quality and water resources management.
The researchers validated their model by comparing model predictions against streamflow data collected by the USGS on rivers such as the Mississippi, Missouri and Ohio.
The model properly portrayed the impact of the drought through decreased streamflow and increased water table depths within the affected region.
unisci.com /stories/20012/0611012.htm   (447 words)

  
 New Scientist Breaking News - Distributed climate model aims for errors
A key use of climate models is to estimate how much the Earth's temperature will rise as the concentration of carbon dioxide in the atmosphere increases.
The climate model used divides the surface of the Earth into boxes measuring hundreds of kilometres across, while the atmosphere and oceans are split into roughly 20 layers.
Of these, 225 still accurately simulated the current climate and were therefore run forwards for 45 years, to measure the effect of doubling the carbon dioxide concentration.
www.newscientist.com /article.ns?id=dn4159   (481 words)

  
 RealClimate » Climate model scenarios Les scénarios des modèles climatiques
Since climate scientists certainly don't have a crystal ball, we generally take a range of scenarios or projections of future emissions of CO and other important forcings such as methane and aerosols.
The models are not going to be able to tell you what will happen in 2080, but more what may happen at the time of doubling of CO whenever that may be.
Models are using these (which range from no further change in greenhouse gases to a 'Business as usual' continuation of the past increases) to run simulations for the next IPCC report due 2007.
www.realclimate.org /index.php?p=3   (756 words)

  
 EdGCM: Climate Modeling for Research and Education - Home
EdGCM, or the Educational Global Climate Model, is a suite of software applications that allows educators and students to run a fully functional 3D global climate model (GCM) on desktop computers in the classroom.
In this report, we simulate the effects of major changes to certain climate forcings in an effort to reproduce, with our model, the climatic conditions suggested by the geologic record.
The first part of this investigation on the last Ice Age was published on MTG Climate in November.
edgcm.columbia.edu   (650 words)

  
 Coupled Parallel Climate Model (PCM) Applications to Climate Change   (Site not responding. Last check: 2007-11-05)
The atmospheric component is the National Center for Atmospheric Research (NCAR) Community Climate Model; the ocean component is the Parallel Ocean Program with a resolution of 32 levels and 2/3 degree horizontal grid; and the sea ice component is the Naval Postgraduate School model using a resolution of 27 km.
This model has higher-resolution ocean and sea ice components than are used in previous coupled climate model simulations; thus we can see much more realistic eddy structures in the ocean that are closer to the observed patterns.
Because of an observed warming of the earth's climate that is probably caused by increased greenhouse gases, the Department of Energy is very interested in making better estimates of possible impacts on future states of climate.
www.nersc.gov /news/annual_reports/annrep98/washington.html   (373 words)

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