Principal Investigator John A Taylor Project m33

Centre for Resource and Environmental Studies Machine VP

Co-Investigators P Zimmerman and D Erickson

Atmospheric Chemistry Division, National Center for Atmospheric Research, USA

A 3-D Tropospheric Transport and Chemistry Model

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.

What are the basic questions addressed?

What are the sources and sinks of the greenhouse gases?

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

Model calculations for the TRANSCOM model intercomparison of atmospheric CO2 were performed this year. 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 developed. These models represent the most detailed and highest resolution models yet developed to study the greenhouse gases. Ultimately, the results of this work are used to quantify the sources and sinks of greenhouse gases, predict future concentrations of greenhouse gases and develop policies to control the release of greenhouse gases to the atmosphere.

What computational techniques are used and why is a supercomputer required?

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 VP2200 require approximately 10 minutes of CPU time at the new higher resolution per model year. A fully vectorized Lagrangian trajectory code has been developed.

Publications

A simulation of methane and methyl chloroform using the NIRE global three-dimensional tracer transport model, S Taguchi and J A Taylor, Proceedings of the International Symposium on Global Cycles of Atmospheric Greenhouse Gases, Sendai, Japan, March 7-11, 319-332 (1994).

Fossil fuel emissions required to achieve atmospheric CO2 stabilisation, J A Taylor, Proceedings of The International Symposium on Global Cycles of Atmospheric Greenhouse Gases, Sendai, Japan, March 7-11, 308-314 (1994).

On the temperature dependence of soil respiration, J J Lloyd and J A Taylor, Functional Ecology, 8, 315-323 (1994).

A global model of natural volatile organic compound emissions, A Guenther, C Hewitt, D Erickson, R Fall, C Geron, T Graedel, P Harley, L Klinger, M Lerdau, B McKay, T Piece, R Scholes, R Steinbrecher, R Tallamraju, J Taylor and P Zimmerman, Journal of Geophysical Research (1994), in press.

A 3-D modelling study of the sources and sinks of atmospheric carbon monoxide, J A Taylor, P R Zimmerman and D J Erickson, Ecological Modelling, in press.

Fossil fuel emissions required to achieve atmospheric stabilisation using ANU-BACE: a box diffusion carbon cycle model, J A Taylor, Ecological Modelling, in press.