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Modeling of microscale variations in methane fluxes

Modeling of microscale variations in methane fluxes. Anu Kettunen Jan 17th, 2003. Solar energy and cycling of elements. Natural green house phenomenon. Atmosphere  surface temperature of Earth ca 30 o C higher than without atmosphere

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Modeling of microscale variations in methane fluxes

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  1. Modeling of microscale variations in methane fluxes Anu Kettunen Jan 17th, 2003

  2. Solar energy and cycling of elements

  3. Natural green house phenomenon • Atmosphere  surface temperature of Earth ca 30oC higher than without atmosphere • Green house gases prevent Solar energy from escaping from Earth • H2O, CO2, CH4, N2O, CFC compounds

  4. Human activities • Use of fossil fuel etc. human actions increase green house gas concentrations = enhances green house phenomenon  climate change Robert T. Watson, IPCC chair

  5. Future climate • On average warmer • Regional differences • Precipitation patterns • Likelihood for extreme events (drought, storms) increases

  6. Mires • Northern mires carbon sinks during last millenia, huge amount of carbon in peat • Sources of green house gases (CO2 ja CH4) • Important to understand role of mires in carbon cycle

  7. Methane • CH4 important green house gas • Concentration increases ca 1% per year • Wetlands (20-30 %), rice paddies, ruminants, landfills, artificial lakes

  8. Research problem • Previously no satisfactory description of spatial and seasonal variations in methane fluxes • Growing season measurument: CH4, T, WT etc. from different mire surfaces • Methane production and oxidaton potentials • Process model connects methane flux to vegetation cover, photosynthetic cycle and peat thermal and moisture conditions

  9. Process model

  10. Model predictions

  11. Fresh carbon, NPP and T • Model sensitive to fresh carbon • If T ja CO2  NPP   substrate  CH4  • If only T  CH4  less

  12. Transport of oxygen to peat • The more sedges transport oxygen to peat, the lower the CH4 flux • If methane oxidation   CH4  Change in transport capacity of sedges

  13. The effect of drought • Long dry periods  methanogens   CH4  • If > 4-6 week drought, no recovery even after rains come

  14. Main contribution of the thesis • Simulation model for CH4 fluxes from different mire surfaces  CH4 fluxes from boreal mires can be predicted under current and future climate • Increased understanding • Connection to general circulation models

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