Climate Modeling (Meteo 523)
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description of Parameterization Project 2.
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Project 3 description.
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AMIP Project 4 discussion for this class. REVISED
Discussion
topics and dates are listed here.
The aim of this class is to familiarize students with the background needed to understand the strengths and limitations of climate models. Background on typical treatments of the numerics is given - and further explored in project form; a typical structure of climate models is presented; and some of the major validation issues are addressed.
Active and interactive learning is strongly encouraged. Thus, the following project topics provide the basis for much of the material to be covered here:
(REVISED: 19 March 1997)
This project consists of a 20 minute conference-style presentation addressing the major components of the climate system. You may choose to do a general overview or elect to be more superficial about most aspects and focus predominantly on one component.
Your audience is a group of non-science professionals in management roles. These are people to whom knowledge of the climate provides useful background in their daily decision making. Such folks might be building engineers, town planners, power and water management, county officers,...
Project Two: Climate Model Parameterization Proposal
(Completed)
Familiarization with assumptions, components and formulation of physical parameterizations in GCMs is the goal of this project. Students will nominate a particular physical process whose parameterizations they will study. Students then adopt one (or possibly more) parameterization of this type, becoming familiar with the inherent assumptions of the parameterization and relating these to the expression of this process in the atmosphere. These links are drawn in consideration of both the atmospheric processes and constraints that must be met in expressing these numerically. Students will perform in the role of scientific investigators, identifying weaknesses in the systems currently available and proposing a course of investigation that would lead to an improved parameterization. Ideally, the proposed improvements would work within the confines of current or near future computational capabilities.Creative investigation and improvements to the parameterization chosen are a necessary component for successful completion of this project. Do not allow your relative newness to the field to limit your imaginations!
Click here for some inspiration for Project 2!
Revised, Tuesday 18 February:
Presentations successfully completed on Tuesday 4th and Thursday 6th of March 1997.
NCAR's Climate and Global Dynamics Group developed this model as a research and teaching tool. You will use this model to familiarize yourselves with the structure of a spectral model. Further, you will design and carry out some numerical experiments of your own to investigate the response of the global circulations to your chosen forcing condition.
Information on the model can be found here.
Information on the test cases used to asses the model performance can be found here.
Please use this information to download your own copy of the model. NOTE I have the datafiles for the NetCDF subdirectory - they are not on the NCAR Web site.
Indicative equivalent resolutions for various GCM truncations are here.
Project Four: AMIP Model Climate Intercomparison
The Atmospheric Model Intercomparison Project (AMIP) has been designed to validate the current generation of climate models. It is ``an international effort to determine the systmatic climate errors of atmospheric models under realistic conditions'' (Gates, BAMS 1992). Over 30 modeling centers are participating in AMIP.
All of the modeling groups participating in AMIP
report their model configurations and agree to run their
atmospheric GCMs for a decade long simulation, using a common SST (sea
surface temperature) and sea ice dataset as the surface forcing. Standard
model outputs are stored and collected in a central data bank at the
Lawrence Livermore National Labs in California. Data
available are given here. More information on the AMIP project and
climate analyses being done or proposed can be found at:
http://www-pcmdi.llnl.gov/amiphome.html
As the build-up to this project, you will have investigated the different ways in which physical processes are parameterized in these models and the schemes used to project forward in time. It is time now to apply this knowledge to the diagnosis of results from actual climate model simulations run under control conditions (the AMIP group of simulations).
4.2.1 GCMs Selected for our Study
REVISED
This GCMs selected for this study are:
The strawman of AMIP model analyses to be performed is as follows:
Inspection of the analysis goals leads me to request these data (all global fields) for each GCM listed above:
Core reference list for this class.
There may be some overlap between the following lists. They are suggestions
for starting points in your reading.
Feel free to explore much
further than these lists.
(i) Broecker, W. S., D. M. Peteet and D. Rind, 1985: "Does the ocean-atmosphere system have more than one stable mode of operation?" Nature, 315, 21-26.
(ii) Manabe, S., and R. J. Stouffer, 1988: "Two stable equilibria of a coupled ocean-atmosphere model". J. Climate, 1, 841-866.
(iii) Toggweiler, R., and B. Samuels, 1997: "On the relative roles of wind forces and buoyancy forces." J. Phys. Oceanogr., (submitted). This paper is available for copying in the front office of Meteorology (503 Walker).
A classic paper on this work (you may also want to reference) is that of Stommel:
Stommel, H., 1961: "Thermohaline convection with two stable regimes of flow". Tellus, 13, 224-230.
FYI, more
references to Dr Toggweiler's work can be found here..
This discussion was sparked (in my mind) by the comments that Suki Manabe made when he was here. You will note that the document you are to read forms the basis of a document to be given to policymakers and government officials. The framework of our class discussion will begin from exploring the two questions of (1) climate model accuracy in a scientific context and (2) translation of climate model results for decisionmakers. The question of whether scientists should be the ones in the front lines here is to be the topic of another discussion, so try to leave it out of this one.
(i) Stephens, G. L., and S.-C. Tsay, 1990: "On the cloud absorption anomaly. Quart. J. Roy. Meteor. Soc., 116, 671-704.
(ii) Cess, R. D., et al., 1989: "Interpretation of cloud-climate feedback as produced by 14 atmospheric general circulation models". Science, 245, 513-516.
(iii) Kiehl, J. T., J. J. Hack, M. H. Zhang and R. D. Cess, 1995: "Sensitivity of a GCM climate to enhanced shortwave cloud absorption". J. Climate, 8, 2200-2212.
Dr Ackerman brings new thoughts from the observational perspective, which he will share with us at the start of class, but I expect you to be familiar with the work in at least these 3 papers.
(i) Hume, B., 1991: "An Intercomparison of model and observed global precipitation climatologies".Geophys. Res. Letters, 18, 1715-1718
(ii) Kaurola, J., 1997: "Some diagnostics of the Northern wintertime climate simulated by the ECHAM3 model ".J. Climate, 10, 201-222.
(iii) Robock, A., et al., 1997:"Soil moisture parameterization in GCMs and evaluation of AMIP simulations". Earth Interactions, (Submitted).
(iv) Wang, W.-C., et al., 1995: "Atmospheric ozone as a climate gas". Atmos. Res., 37, 247-256.
Copies of all but the GRL paper are available with Dana in Room 503 Walker.
(i) Bengtsson, L., H. Bottger and M. Kanamitsu, 1982: "Simulation of hurricane-type vortices in a general circulation model". Tellus, 34, 440-457.
(ii) McBride, J. L., 1984: "Comments on Simulation of hurricane-type vortices in a general circulation model. Tellus, 36A, 92-93.
(iii) Bengtsson, L., H. Bottger and M. Kanamitsu, 1984: "Reply to a comment by J. L. McBride". Tellus, 36A, 94-96.
(iv) Broccoli, A. J., and S. Manabe, 1990: "Can existing climate models be used to study anthropogenic changes in tropical cyclone climate?" Geophys. Res. Letters, 17, 1917-1920.
(v) Evans, J. L., 1992: "Comment on Can existing climate models be used to study anthropogenic changes in tropical cyclone climate?". Geophys. Res. Letters, 19, 1523-1524.
(vi) Broccoli, A. J., and S. Manabe, 1992: "Reply to Evans". Geophys. Res. Letters, 19, 1525-1526.
(vii) Bengtsson, L., M. Botzet and M. Esch, 1994: "Will greenhouse gas-induced warming over the next 50 years lead to a higher frequency and greater intensity of tropical cyclones?". Max-Planck-Institut fur Meteorologie Report No. 139, Hamburg, August 1994.
(viii) Ryan, B. F., I. G. Watterson and J. L. Evans, 1992: "Tropical cyclone frequencies inferred from Grays yearly genesis parameter: Validation of GCM tropical climates". Geophys. Res. Letters, 19, 1831-1834.
Project 4 meeting dates are scheduled below. If the results are there to discuss and process - and draft - I am willing to begin work on them next Tuesday. See the revisions for the remainder of the semester. You should all be nearing some results by now.
(i) Giorgi, F., 1990: "Simulation of regional climate using a limited area model nested in a general circulation model". J. Climate, 3, 941-963.
(ii) Risbey, J. S., and P. H. Stone, 1996: "A case sudy of the adequacy of GCM simulations for input to regional climate change assessments". J. Climate, 9, 1441-1467.
(iii) Giorgi, F., and L. Mearns, 1991: "Approaches to the simulation of regional climate change: a review". Rev. Geophysics, 29, 191-216.
(i) Kutzback, J. E., P. J. Guetter, W. F. Ruddiman and W. L. Prell, 1989: ``Sensitivity of climate to Late Cenozoic uplift in south Asia and the American west: Numerical experiments''. J. Geophys. Res., 94 (D15), 18393-18407.
(ii) Kutzback, J. E., W. L. Prell and W. F. Ruddiman, 1993: ``Sensitivity of Eurasian climate to surface uplift of the Tibetan Plateau''. J. Geology, 101, 177-190.
(i) Thompson, S., and S. Schneider, 1979: ``A seasonal zonal energy balance climate model with an interactive lower layer''. J. Geophys. Res., 84 (C5), 2401-2414.
(ii) Stocker, T. F., D. G. Wright and L. A. Mysak, 1992: ``A zonally averaged, coupled ocean-atmosphere model for paleoclimate studies''. J. Climate, 5, 773-797.
Seminar
entitled ``Millenial-scale climate variability during the Holocene, last
glaciation and last interglacial in the subpolar North Atlantic - Ice sheet
versus ocean-atmosphere forcing'' will be given by Gerard Bond
(Lamont-Dougherty) in Room 112 Walker on Tuesday, 29 April at 4pm.
Those of
you interested in ocean-atmosphere interactions on shorter climate timescales
should consider applying for the NCAR Summer Colloquium from 20 July to 1
August 1997. The topic is ``A systems approach to El Nino/Southern
Oscillation (ENSO): Oceanic, atmospheric, societal, environmental and policy
perspectives''.
Last Updated: April 23, 1997
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