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Encyclopedia > HadCM3

HadCM3 (Hadley Centre Coupled Model, version 3) is a coupled atmosphere-ocean general circulation model (AOGCM) developed at the Hadley Centre in the United Kingdom and described by Gordon et al (2000) and Pope et al (2000). It was one of the major models used in the IPCC TAR in 2001. ... The Hadley Centre for Climate Prediction and Research, which is part of the Met Office, provides a focus in the United Kingdom for the scientific issues associated with climate change. ... IPCC is science authority for the UNFCCC The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess the risk of human-induced climate change. The Panel is open to all... The Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) was issued in 2001. ...


Unlike earlier AOGCMs at the Hadley Centre and elsewhere (including its predecessor HadCM2), HadCM3 does not need flux adjustment (additional "artificial" heat and freshwater fluxes at the ocean surface) to produce a good simulation. The higher ocean resolution of HadCM3 is a major factor in this; other factors include a good match between the atmospheric and oceanic components; and an improved ocean mixing scheme (Gent and McWilliams). HadCM3 has been run for over a thousand years, showing little drift in its surface climate.


HadCM3 is composed of two components: the atmospheric model HadAM3 and the ocean model (which includes a sea ice model).

Contents

Atmosphere model (HadAM3)

Zonal mean temperatures in JJA (top) and DJF (bottom)
Zonal mean temperatures in JJA (top) and DJF (bottom)

HadAM3 is a grid point model and has a horizontal resolution of 2.5x3.75 degrees in latitude x longitude. This gives 96x73 grid points on the scalar (pressure, temperature and moisture) grid; the vector (wind velocity) grid is offset by 1/2 a grid box. [1]. This gives a resolution of approximately 300 km, roughly equal to T42 in a spectral model. There are 19 levels in the vertical. Image File history File links Download high-resolution version (800x787, 27 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): HadCM3 User:William M. Connolley/My Images/Computer-generated images ... Image File history File links Download high-resolution version (800x787, 27 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): HadCM3 User:William M. Connolley/My Images/Computer-generated images ... NCEP T62 gaussian grid points A gaussian grid is used in the earth sciences as a grid for scientific modeling on a sphere (i. ...


The timestep is 30 minutes (with three sub-timesteps per timestep in the dynamics). Near the poles, fields are fourier-filtered to prevent instabilities due to the CFL criterion. In mathematics, the Courant–Friedrichs–Lewy condition (CFL condition) is a condition for certain algorithms for solving partial differential equations to be numerically stable. ...


Ocean model (HadOM3)

Ocean temperatures
Ocean temperatures

The ocean model has a resolution of 1.25x1.25 degrees and a timestep of 1 hour. Thus there are 6 ocean grid points for every atmospheric one. For ease of coupling the two models the grids are aligned and the ocean coastline is forced to be aligned to the atmospheric grid. Image File history File links Download high-resolution version (799x787, 10 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): HadCM3 User:William M. Connolley/My Images/Computer-generated images ... Image File history File links Download high-resolution version (799x787, 10 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): HadCM3 User:William M. Connolley/My Images/Computer-generated images ...


Coupling

The atmospheric model is run for a day, and the fluxes (of heat, moisture and momentum) at the atmos-ocean interface are accumulated. Then the ocean model is run for a day, with the reverse fluxes accumulated. This then repeats through the length of the run. Unlike its predecessor HadCM2 there is no need for flux correction - the model climate remains stable and does not significantly drift. The lack of flux correction is cited by the IPCC as one of the advances in modelling since the SAR [2]. SAR may stand for: (in pharmacology and computational chemistry) structure-activity relationship In plant disease resistance Systemic acquired resistance Salanter Akiba Riverdale, a modern Orthodox yeshiva in Riverdale, New York Saudi riyal (ISO 4217 currency code SAR) Search and rescue IPCC Second Assessment Report Segmentation and Reassembly of data packets...


The ocean model incorporates a thermodynamic-dynamic seaice model with a primitive (ocean drift) dynamics.


Slab model (HadSM3)

The atmospheric model may be run coupled to a simpler "slab ocean" rather than the full dynamic ocean. This is faster (and requires less memory) than the full model, but lacks dynamical feedbacks from the ocean, which are incorporated into the full coupled-ocean-atmosphere models used to make projections of climate change out to 2100. To do this the model needs a calibration phase in which the ocean temperatures are held to climatology while it calculates the "flux correction"; extra ocean-atmosphere fluxes that would be needed to keep the model ocean in balance (the model ocean does not include currents; these fluxes to some extent replace the heat that would be transported by the missing currents). Then the model may be run in climate mode.


See also

Attribution of recent climate change is the problem of discovering what mechanisms are responsible for observed changes in climate. ... ESC cabinets The Earth Simulator (ES) was the fastest supercomputer in the world from 2002 to 2004, located at the Earth Simulator Center (ESC) in Kanazawa-ku (ward), Yokohama-shi, Japan. ... The National Center for Atmospheric Research (NCAR), in Boulder, Colorado, was established in 1960 to serve as a focus for United States research on atmospheric and related science problems, including climate change, atmospheric chemistry, changes in atmospheric composition, mesoscale and microscale meteorology, Earth-Sun interactions, weather formation and forecasting, and... EdGCM is an educational version of a global climate model (GCM) that has been ported for use on desktop computers and integrated with a relational database, a graphical user interface, and scientific visualization utllities, all of which are aimed at helping improve the quality of teaching and learning of climate...

External links

  • http://www.met-office.gov.uk/research/hadleycentre/models/HadCM3.html
  • http://cera-www.dkrz.de/IPCC_DDC/IS92a/HadleyCM3/hccpruns.html

References

  • Gordon, C., C. Cooper, C.A. Senior, H. Banks, J.M. Gregory, T.C. Johns, J.F.B. Mitchell and R.A. Wood, 2000: The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments. Climate Dynamics 16: 147-168 [3].
  • Pope, V. D., M. L. Gallani, P. R. Rowntree and R. A. Stratton, 2000: The impact of new physical parameterizations in the Hadley Centre climate model -- HadAM3. Climate Dynamics, 16: 123-146 [4].

  Results from FactBites:
 
HadCM3 - Wikipedia, the free encyclopedia (457 words)
HadCM3 ( Had ley Centre C oupled M odel, version 3) is a coupled atmosphere-ocean general circulation model (AOGCM) developed at the Hadley Centre and described by Gordon et al (2000) and Pope et al (2000).
The higher ocean resolution of HadCM3 is a major factor in this; other factors include a good match between the atmospheric and oceanic components; and an improved ocean mixing scheme (Gent and McWilliams).
HadCM3 is composed of two components: the atmospheric model HadAM3 and the ocean model (which includes a sea ice model).
Draft for CLIVAR Exchanges Mag. (2210 words)
HadCM3 has an atmosphere with a 3.75x2.5 degree longitude-latitude grid and 19 vertical levels, and an ocean with a 1.25x1.25 degree grid and 20 levels in the vertical.
A simple yet quantitative way of comparing the variability of HadCM3 with the tree-ring estimates is to compute the variance (or standard deviation) of temperature regionally and over the northern hemisphere as a whole (fig 2a-b).
The control simulation of HadCM3 only represents the "internal" variability of the climate system - that which is a consequence of non-linear interactions within (and between) the atmosphere and the ocean.
  More results at FactBites »

 
 

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