INTRODUCTION

1. Carbon, Energy and Water Cycles Across Australia’s ‘Top End’Stephen Wood1, Jason Beringer1, Nigel Tapper1, Lindsay Hutley2, Jorg Hacker3, Kyaw Tha Paw U4 Air Temperature Spec. Humidity Vertical Wind Horizontal Wind Sensible Heat Latent Heat Surface Temperature Altitude (m) Trees and Shrubs (m) Flying height (m) 1 2 3 1School of Geography and Environmental Science, Monash University, Clayton, Victoria, 3800, Australia;2 Faculty of Education, Health and Science, Charles Darwin University, Darwin, NT, Australia;3Airborn Research Australia, The Flinders University of South Australia, Salisbury, SA, 5106, Australia;4Department of Land, Air and Water Resources, University of California, Davis, CA 95616, USA; Contact: stephen.wood@arts.monash.edu.au • INTRODUCTION • Savannas account for 30% of net primary production (NPP) of all terrestrial vegetation (Grace et al., 2006), Giving them the potential to influence the global carbon cycle (Chen et al., 2003). • Savannas cover 16 million km2, ~20% of the Earth’s surface. making them a major ecosystem in the global carbon cycle (Grace et al., 2006). • The wet-dry tropics of Northern Australia features ~2 Million km2 of savanna vegetation, equivalent to 12.5% of the worlds tropical savannas (Scholes and Hall, 1996) OBJECTIVE 3:Aircraft transect data and boundary layer budgeting will be used to map the spatial variability of the landscape. This data will be used to validate the results from the model used to expand from point to region. The aircraft being used are 2 Diamond aircraft HK36TTC ECO-Dimona from Airborne Research Australia that can fly from 5-7000m. • ~25% of the Australian continent (O'Grady et al., 1999), making this region one of global significance (Beringer et al., 2003, Williams et al., 2005). • In Australia, savannas occur in North-West Western Australia, the northern half of the Northern Territory and northern Queensland (Figure 1) Transects are done to cover a selected area so spatial variability can be recorded (LEFT) Figure 3: (ABOVE) Comparison between the energy balance and radiation balance at Howard Springs, Daly River and Fogg Dam. Figure 4. (LEFT) Comparison between the CO2 fluxes at Howard Springs, Daly River and Fogg Dam Figure 1: Map of Australia indicating extent of tropical savanna in Northern Australia. Source: Tropical Savannas CRC. There has been a large amount of data collected around Darwin through other studies (Figure 3), however this data focuses on the temporal variability and it is necessary to understand how carbon, water and energy vary spatially across the northern Australian landscape before we can fully grasp the carbon budget of this region. OBJECTIVE 2:The CSIRO atmosphere biosphere land exchange (CABLE) model and the advanced canopy-atmosphere-surface algorithm (ACASA) will be used to simulate the eddy covariance results. The model that does this best will be used to expand from point to region. Within a mesoscale model The results of one of these transects show the extent of data that can be measured (ABOVE) OBJECTIVE 1:The spatial variability of the carbon, water and energy cycles will be measured using eddy covariance towers at 3 different sites, representing key terrestrial ecosystem types. Enabling us to observe significant differences during the wet and dry seasons and what characteristics drive this variability. The transect data can be used to map the spatial variability of chosen factors e.g. Latent and Sensible heat. This will then be compared to the results from the modelling. (LEFT) CABLE consists of 3 submodels: 1) canopy microclimate, 2) soil and snow, 3)Cabon pool and soil respiration ACASA is made up of several main components: 1) vertical resolution, 2) surface temperature calculations, 3) turbulance closure, 4) physiological response, 5) soil moisture and heat transfer Sites OBJECTIVE 4:The model that best simulates the results from the key ecosystem types will be used along with historic data from the Bureau or Meteorology to show a time line of the fluxes in the region over the past decades. This will enable us to document past events such as El Niño Southern Oscillation (ENSO) and monsoon onset for the region over a significant period. This project will create tools for the spatially explicit determination of carbon, water and energy budgets for the ‘Top End’ region, which will assist in the management of Northern Australian ecosystems for carbon uptake. It will also provide new information to the existing National Carbon Accounting System (NCAS). References Beringer, J., Hutley, L. B., Tapper, N. J., Coutts, A., Kerley, A. and O'Grady, A. P., (2003) Fire impacts on surface heat, moisture and carbon fluxes from a tropical savanna in northern Australia. International Journal of Wildland Fire12: 333-340. Chen, X. Y., Hutley, L. B. and Eamus, D., (2003) Carbon balance of a tropical savanna of northern Australia. Oecologia137: 405-416. Grace, J., San Jose, J., Meir, P., Miranda, H. S. and Montes, R. A., (2006) Productivity and carbon fluxes of tropical savannas. Journal of Biogeography33: 387-400. Scholes, R. J. and Hall, D. (1996) In Global change : effects on coniferous forests and grasslands(Eds, Breymeyer, A. I., Hall, I. D., Melillo, J. M. and Agren, G. I.) John Wiley, New york, pp. 69-100. Tropical Savanna CRC http://savanna.ntu.edu.au/ Williams, R. J., Carter, J., Duff, G. A., Woinarski, J. C. Z., Cook, G. D. and Farrer, S. L., (2005) Carbon accounting, land management, science and policy uncertainty in Australian savanna landscapes: introduction and overview. Australian Journal Of Botany53: 583-588. Figure 5: Visual representation of the processes within MM5-ACASA (ABOVE). Figure 6: Schematic of the components and implementation of ACASA (RIGHT). Figure 7: Schematic of the components and implementation of CABLE (FAR RIGHT). Acknowledgements We would like to thank the Australian Research Council (ARC) for funding this project (DP0772981). Figure 2: Photos of 1) Howard Springs, 2) Daly River and 3) Fogg Dam showing the EC towers