Influence of savanna fire on Australian monsoon season precipitation and circulation as simulated using a distributed computing environment

Geophysical Research Letters (Impact Factor: 4.46). 01/2007; 34(20):20801-20801. DOI: 10.1029/2007gl030879

ABSTRACT Fires in the Australian savanna have been hypothesized to affect monsoon evolution, but the hypothesis is controversial and the effects have not been quantified. A distributed computing approach allows the development of a challenging experimental design that permits simultaneous variation of all fire attributes. The climate model simulations are distributed around multiple independent computer clusters in six countries, an approach that has potential for a range of other large simulation applications in the earth sciences. The experiment clarifies that savanna burning can shape the monsoon through two mechanisms. Boundary-layer circulation and large-scale convergence is intensified monotonically through increasing fire intensity and area burned. However, thresholds of fire timing and area are evident in the consequent influence on monsoon rainfall. In the optimal band of late, high intensity fires with a somewhat limited extent, it is possible for the wet season to be significantly enhanced.

1 Follower
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Debate concerning the environmental impact of human arrival in Australia has continued for more than a century. Here we review the evidence for human impact and the mechanisms by which humans may have affected the environment of tropical Australia. We limit our review to tropical Australia because, over three decades ago, it was proposed that the imposition of an anthropogenic fire regime upon human occupation of the Australian continent may have resulted in profound changes in regional vegetation and climate across this region. We conclude that ecological processes and vegetation–fire–climate–human feedbacks do exist that could have driven a significant shift in boundary conditions and ecosystem state at the sub-continental scale through the sustained imposition of an anthropogenic fire regime over tens of millennia. These potential feedbacks operate through the inhibition of forest expansion both directly, by targeted burning at established forest edges and newly irrupted forest patches, and indirectly, through lengthening of the dry season because of changes to the timing of burning. However, the impact of any such anthropogenic forcing may have been entirely overshadowed by the effects of natural climate change and variability, as well as the generally low nutrient status of Australian soils. A robust assessment of the degree to which the environment of tropical Australia at the large scale has been modified from its 'natural' state because of human occupation will require new, coordinated collaborations between indigenous traditional landowners, archaeologists, anthropologists, geochronologists, geoscientists, ecologists, climatologists and modellers.
    Journal of Quaternary Science 07/2013; 28(5):439-452. DOI:10.1002/jqs.2639 · 2.66 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Savanna ecosystems comprise 22% of the global terrestrial surface and 25% of Australia (almost 1.9 million km2) and provide significant ecosystem services through carbon and water cycles and the maintenance of biodiversity. The current structure, composition and distribution of Australian savannas have co-evolved with fire, yet remain driven by the dynamic constraints of their bioclimatic niche. Fire in Australian savannas influences both the biophysical and biogeochemical processes at multiple scales from leaf to landscape. Here we present the latest emission estimates from Australian savanna biomass burning and their contribution to global greenhouse gas budgets. We then review our understanding of the impacts of fire on ecosystem function and local surface water and heat balances, which in turn influence regional climate. We show how savanna fires are coupled to the global climate through the carbon cycle and fire regimes. We present new research that climate change is likely to alter the structure and function of savannas through shifts in moisture availability and increases in atmospheric carbon dioxide (CO2), in turn altering fire regimes with further feedbacks to climate. We explore opportunities to reduce net greenhouse gas emissions from savanna ecosystems through changes in savanna fire management.This article is protected by copyright. All rights reserved.
    Global Change Biology 07/2014; 21:62 - 81. DOI:10.1111/gcb.12686 · 8.22 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The sensitivity of the global sea-ice distribution in the Australian Climate Ocean Model (AusCOM) to a range of parameter values related to sea-ice physics was explored. The sea-ice component of AusCOM is the U.S. Los Alamos National Laboratory Sea Ice Model (CICE4.1) and the ocean component is the Modular Ocean Model developed at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL MOM4p1). We aimed to determine optimal sets of parameter values to produce as realistic a global sea-ice distribution as possible. A small number of sets of optimal parameter values was selected based on the closest match between the model and observationally constrained model climatologies. New detailed information is provided on the sensitivity of the global sea-ice distribution to the parameters not studied this extensively before. The sea-ice distribution shows a similar degree of sensitivity to parameters determining ice-ocean stress, mechanical redistribution, oceanic heat and shortwave radiation. Accordingly, AusCOM can be effectively tuned to produce realistic sea ice by parameters internal to the sea-ice model. The sensitivity of ice volume is stronger than that of ice area indicating that the internal ice model parameters mostly influence the ice thickness. The sea-ice area has significantly weaker sensitivity to the sea-ice model parameters considered, particularly in winter. Then, the evolution of sea ice is dominated by external factors, such as location of land, and atmospheric and oceanic forcing. The performance of the ocean model is crucial in producing a realistic sea-ice cover, in both the Arctic and the Antarctic.
    Ocean Modelling 07/2012; DOI:10.1016/j.ocemod.2012.04.002 · 2.59 Impact Factor


Available from
May 26, 2014