A 3-D Tropospheric Transport and Chemistry Model

Principal Investigator

John A Taylor

Centre for Resource and Environmental Studies

The study of the biogeochemical cycles of greenhouse gases has become a problem of considerable concern to both the scientific community and the general public. The primary concern associated with the large-scale change in the chemistry of the atmosphere has been with the potential for producing a substantial global warming. The study of the atmospheric chemistry and the biogeochemical cycles of greenhouse gases represents an important and challenging area of scientific research which aims to improve our understanding of climate change arising from the anthropogenic alterations to the composition of the atmosphere. A major problem facing research into the biogeochemical cycles of greenhouse gases has been the need to develop high-resolution three-dimensional models of the sources and sinks, atmospheric transport and chemistry of these gases which have in the past, placed enormous computational demands even on supercomputers. This project has involved the development of a highly efficient atmospheric transport model. The basic approach of the model is to divide the atmosphere into 1,000,000 air parcels of equal mass. Trajectories for these air parcels are calculated using available global wind field data. While the air parcels are being transported around the globe they are able to exchange chemical species between the oceans and the biosphere, receive industrial emissions of greenhouse gases and exchange chemical species amongst themselves . Model simulations using the NCAR CCM2/CCM3 global climate models have also been undertaken in collaboration with researchers in the United States to study the impact of biomass burning on climate. Initial results of this work have been reported.

Co-Investigators

P Zimmerman

D Erickson

Atmospheric Chemistry Division

National Center for Atmospheric Research, USA

Projects

m33 - VPP, PC


What are the results to date and future of the work?

Model calculations for the TRANSCOM model intercomparison of atmospheric CO2 were carried out. High-resolution 3-D models of the sources and sinks, atmospheric transport and chemistry of the greenhouse gases CO2, CFC-11, CFC-12, methyl chloroform, methane and nitrous oxide have been developed. A model of the sources and sinks of CO, an important atmospheric trace gas, has also been completed. The latest development has been the



modification of the model to perform simulations using ECMWF data sets for the time period 1980-1994 and the incorporation of a model of the atmospheric boundary-layer. Ultimately, the results of this work are used to quantify the sources and sinks of greenhouse gases, predict future concentrations of greenhouse gases, study the impact of greenhouse gas emissions on present and future climate and develop policies to control the release of greenhouse gases to the atmosphere.

What computational techniques are used?

Three-dimensional computations of high resolution atmospheric transport and chemistry are extremely intensive. The models demand large amounts of memory and generate large amounts of output. Model runs on the new VPP-300 require approximately 8 minutes of CPU time at the new higher resolution per model year. A fully vectorized Lagrangian trajectory code has been developed.

Publications

Taylor J.A., Zimmerman P.R. and Erickson D.J. III (1996) A 3-D modelling study of the sources and sinks of atmospheric carbon monoxide, Ecological Modelling 53-71.

Taylor J.A.(1996) Fossil fuel emissions required to achieve atmospheric stabilisation using ANU-BACE: a box diffusion carbon cycle model. Ecological Modelling, 195-199.

Bouwman A.F. and Taylor J.A. (1996) Testing high-resolution nitrous oxide emission estimates against observations using an atmospheric transport model. Global Biogeochemical Cycles, 307-318.

Klinger L.F., Taylor J.A. and Franzen, L.G. (1996) The potential role of peatland dynamics in Ice-Age initiation, Quaternary Research 89-92.

Taylor J.A.(1996) Global Carbon Dioxide Sinks: An investigation of the role of the biosphere in the tropics and middle to high latitudes in the Northern Hemisphere. Mathematics and Computers in Simulation (in press).

Hyman D.E., Whitehouse D.R., Taylor J.A., Larson J.W. and Lindesay, J.A.(1996) The ANU Translator: Facilitating computer visualization and data analysis of climate model outputs. Environmental Software, (in press).

Marshall S., Taylor J.A., Prager S.D., Oglesby R.J., Larson J.W. and Erickson III, D.J. (1996) Climatic effects of biomass burning. Environmental Software , 51-58 (1996).

Hansen D., Larson J.W. and Taylor J.A.(1996) The NCAR CCM2 (Community Climate Model 2) on the ANU Fujitsu VP2200. Environmental Software (in press).

Rayner P.J., Law R.M. with model results from Denning A.S., Erickson III D.J., Heimann M., Law R.M., Piper S.C., Ramonet M., Rayner P.J., Taguchi S., Taylor J.A., Trudinger C.M. and Watterson I.G. (1996) A comparison of modelled responses to prescribed CO, Global Biogeochemical Cycles (in press)

- Appendix A