Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh
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![“Today, a new scientific revolution is emerging [...] where groups
of scientists are producing global scale information on carbon
and water fluxes. They are doing so by merging of information
from networks of flux towers, biophysical models, ecological
databases and satellite-based remote sensing to produce a new
generation of flux maps.”
Dennis Baldocchi, UC Berkeley](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
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Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh
- 1. Helen Cleugh and Eva van Gorsel Near-real-time measurement of CO2, water and energy fluxes: Determining the best available estimates of continental carbon and water fluxes
- 2. “Today, a new scientific revolution is emerging [...] where groups of scientists are producing global scale information on carbon and water fluxes. They are doing so by merging of information from networks of flux towers, biophysical models, ecological databases and satellite-based remote sensing to produce a new generation of flux maps.” Dennis Baldocchi, UC Berkeley
- 3. Why are we interested in fluxes? Globally terrestrial ecosystems annually sequester about one quarter of anthropogenic emissions of CO2 They provide an ecosystem service worth millions of dollars In sequestering carbon they also use water. Water use by vegetation (through evapotranspiration) is the biggest loss term in the terrestrial water budget Through land management, evapotranspiration is the only term in the water budget that we can manage Terrestrial landscapes also affect the local and regional climate through changing the surface properties of reflectance and roughness Quantifying the exchanges of carbon, water and energy in space and time provides critical information required to underpin the sound management of Australia’s landscapes and the ecosystem services they provide
- 4. Purpose is to measure ecosystem fluxes CO2 and water vapour using eddy covariance method - Water ( E, ET) and CO2 (NEE) Energy - Radiation (Q) and heat (H, G) Above canopy; spatially-averaged Continuous: hourly to multi-annual OzFlux infrastructure and processes A continental network of flux stations NEE ET H Q G ET Q
- 5. Drivers: • Above-canopy meteorology • Soil temperature and moisture Data for analysis & interpretation: • Within-canopy temperature, CO2, humidity and wind profiles Purpose is to measure ecosystem fluxes and … OzFlux infrastructure and processes A continental network of flux stations Flux towers measuring vineyard and forest CO2 and water fluxes
- 7. time scales involved in the land – air exchanges of carbon and water after M.Williams et al., www biogesciences.net/t/1341/2009/
- 8. spatial scales involved... ... span about 14 orders of magnitude after D. Baldocchi, 5th annual flux course, 'Biosphere Breathing' Chloroplast: 10-6 m Stomata: 10-5 m Plant: 1-100 m Leaf: 0.01-0.1 m Canopy: 100-1000 m Globe: 10'000 km Landscape: 1-100 km Continent: 1000 km
- 9. time and length scales covered Courtesy P. Isaac Seconds Minutes TimeScale 10-3 10-2 10-1 100 101 102 103 104 metres Length Scale 10-1 100 101 102 103 104 105 106 Leaf Canopy Patch Region Days Years seconds Leaf Level Observations Flux Tower Aircraft Fluxes Aircraft Remote Sensing Satellite Remote Sensing Land Surface Model GCM Plot Level Observations Leaf Level Physiology assumed to apply Direct measurement Indirect measurement (remote sensing) Modelling Remote sensing observations are rich in spatial information content and can be used to ‘scale up’ from local to larger scales Tower observations provide information on ecosystem processes for the exchanges of energy, water and carbon on all relevant time scales. Scaling up through modelling allows quantification through space and time and physical understanding.
- 12. Observations for BIOS2 constraints and evaluation
- 13. Multiple constraints on Australian terrestrial Net Primary Production: Eddy flux data provide the tightest constraint error bars = uncertainty from propagated parameter uncertainties (1 ) NPP (GtC y -1 ) 0 1 2 3 4 Eddy fluxes + Litterfall + Streamflow Streamflow + Eddy fluxes Streamflow + Litterfall Eddy fluxes + Litterfall Litterfall Streamflow Eddy fluxes Prior estimate
- 14. A reality check - comparing OzFlux measured ET, GPP and BIOS2 simulations Monthly Monthly Annual Annual
- 15. BIOS2 evaluation: comparison with Viscarra Rossel observation-based soil carbon
- 16. AustralianCO2Budget Haverd et al. 2013 a, b. Biogeosciences
- 17. Concluding comments: carbon and water budgets at ecosystem to continental scales OzFlux data have been used to: • Test and improve the land surface model [CABLE] for Australian ecosystems • CABLE is part of Australia’s newly developed global climate model [ACCESS] • Significantly reduce the uncertainty in estimated NPP for Australia, using CABLE as part of BIOS2 • Foundation for the first comprehensive carbon budget for Australia
- 18. OzFlux 2013 Sites 28 Accounts 96 Site-years 62 11 years of ecosystem breathing at Tumbarumba, NSW
- 19. Thank You and Questions Acknowledgements TERN HQ • Tim, Stuart, Guru and the team OzFlux • Ray Leuning – Founding OzFlux Director • OzFlux Steering Committee: Mike Liddell, Lindsay Hutley, Jason Beringer, Wayne Meyer, Alex Held, Peter Isaac • OzFlux PIs Collaborators • Vanessa Haverd • FluxNet
- 20. Concluding comments: carbon and water budgets at ecosystem to continental scales Insights into the carbon and water budgets for the Australian continent, e.g.: • Large inter-annual variability in NPP driven by variation in available moisture • Larger than anthropogenic greenhouse gas emissions
- 21. 3. Connections: Australia Regional carbon and water budgets (e.g. RECCAP) Australian Water Resources Assessments Australian Climate Change Science Program Climate and Earth System Modelling (ACCESS) OzFlux And TERN Australian ecosystem and climate science
- 22. 3. Connections: Global FLUXNET GEWEX Future Earth: WCRP - ESSP NEON OzFlux And TERN Global ecosystem, climate and Earth system science
- 23. A capability to determine carbon and water budgets at ecosystem to continental scales • Uptake and release of CO2 and other GHG [fluxes] • Carbon stocks in soil, plants and air [stores] • Water and carbon • Measurements and models …. the TERN infrastructure “ecosystem”
- 24. …. the TERN infrastructure “ecosystem” Knowledge of ecosystem exchange of carbon, water & energy Vegetation type GPP Veg indices (NDVI, EVI) Leaf area index Fire Canopy properties ..... CO2 and H2O Fluxes Radiation Meteorology Site characteristics Biomass Soil carbon & nutrients Leaf-level photosynthesis Data assimilation and integration into modelling applications AusPlots and Australian Supersites Network OzFlux Network eMASTAusCover
- 25. abstract The role played by natural land and ocean sinks in sequestering greenhouse gas (GHG) emissions, and the trajectory of these sinks into the future, is critically important information needed to underpin climate mitigation and adaption policies. Providing this information requires carbon cycle observations that track the uptake and release of greenhouse gases in land, air and oceans over long periods so that effects of a varying and changing climate, along with land management, can be captured. Climate models need to adequately represent ecosystems and ecosystem processes to provide credible and useful future scenarios. We also need information on how land can be managed to maximise carbon uptake and thus mitigate GHG emissions, including the effect of elevated carbon dioxide levels on plants. This talk will describe the capability needed to determine carbon and water budgets at ecosystem to continental scales – much of which has been developed by TERN, the Terrestrial Ecosystem Research Network. The talk will then focus on the important role that OzFlux plays through directly measuring the exchanges of energy, water and CO2 and the use of these measurements in determining carbon, GHG and water budgets and therefore answering these critical questions.
Editor's Notes
- The Australian terrestrial carbon budget has been published with an a companion paper which looks at the modeling behind the biospheric contribution.This work was motivated by a global study, called RECCAP, which is an initiative of the global carbon project, led by Pep Canadell. A main aim is to try to reconcile top down and bottom up estimates of the global carbon budget where the top down is derived from atmospheric concentrations of the CO2 growth rate and the bottom up is derived by combining regional estimates of carbon budgets, so by taking large terrestrial regions (10) of which Australia is one and large ocean basins. So with this work we attempt to get the best possible estimate of the Australian contribution to the global carbon budget.
- I am going to dive into more detail into some of the large components of the carbon budget and I am going to start with NPP and NEP which we define here as the difference between NPP and Heterotrophic Respiration in the absence of disturbance.NPP and NEP components were derived using the modelling framework BIOS2, constrained by multiple observation types, and forced using remotely sensed vegetation cover.BIOS2 is a fine-spatial-resolution (0.05) offline modelling environment built on capability (initially developed for the Australian Water Availability Project)It includes a modification of the CABLE land surface scheme with additional funcionality around soil hydrology and evaporation, the SLI soil model and the CASA-CNP biogeochemical model. BIOS2 parameters are constrained and predictions are evaluated using multiple observation sets from across the Australian continent, including streamflow from 416 gauged catchments, eddy flux data (CO2 and H2O) from 12 OzFlux sites, litterfall data, and data on soil, litter and biomass carbon poolsAny non-zero NEP is resulting from a combination of climate variability and rising CO2 and we will deal with desturbance effects seperately
- This map presents the location of the observations used to constrain the BIOS2-modellingFlux sites, already mentioned, a range of carbon stock information, also streamflow which is a constraint on the water balance which is intrinsically coupled to the carbon balance via photosynthesis
- Similar plot as before, but this is a reality check:Verification – using allConstraints - Tumba, HS and Daly’s – see map at Slide 20Some important differences: tell us where the model is deficient: another role that the collected data sets have
- We have also been using a observation based soil carbon product from Raphael Viscarra Rossel, This map was derived using spectroscopic measurements of soil organic C and soil bulk density of a couple of thousand soil samples across the continent and using predictive spatial modeling to develop relationships between soil organic C density and a suite of environmental variables that accounted for climate, vegetation, soil type and geology, topography and land use.On the left BIOS map, right obs based product, the bar plot shows the level of regional agreement which is quite good!
- Check numbersThis is an overview of the Australian territorial carbon budget for the 1990–2011 periodThe boxes denote stores, the arrows denote fluxes. What that tells immediately is that the biosphere is accumulatig carbon at the rate of 59 TgC/year during the budget period and is much smaller than the amount of carbon that is emitted by fossil fuel burning.That number of 59 is actually the net impact of NPP and all the losses of carbon from the biosphere. The major loss is due to heterotrophic respiration (90%). Fire accounts for 6% (of NPP), LUC for about 1%, about 1% through the combined effects of logging, harvest and life stock production and a small amount is transported offshore by rivers and dust.We also want to point out that for the change of FF we see that 95 TgC/yr is released from FFburning but a much larger amount is actually shipped offshore. What that means is that our contribution to the accumulation in the atmosphere is actually dominated by our non territorial contribution, which is largely dominated by fossil fuel export.
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- Net primary production is slightly larger (uptake) than heterotrophic respiration, largely because of the CO2 fertilisation effect. This leads to a small positive net ecosystem production (uptake), which is negated by fire and land use change emissions to give a small net biome production that is an emission. The interannual variability of net biome production is driven largely by variation in net ecosystem production due to moisture availability. This interannual variability is significantly larger than the entire greenhouse gas emissions (in GT C(eq) y-1).NBP = 0.056 Pg C year – emission; interannual variability about 0.4 Pg C, cf 0.15 CO2 emissionsNEP (NEE) Uptake about 0.1; cf 0.15 for anthropogenicTotal land atmopshere exchange for Australia is 0.15 + 0.0506 = 0.205 Pg C year.
- The benefits of this cooperative development of data infrastructure are beginning to be realised, inside and outside the OzFlux community. Other research groups within Australia (e.g. the Regional Carbon Cycle Assessment Program) and the international ecosystem exchange community (via FluxNet) are already achieving efficiency and productivity gains by routinely using OzFlux-generated data for their projects. OzFlux remains committed to further refining its data infrastructure as it continues into its second decade of flux data collection.
- The benefits of this cooperative development of data infrastructure are beginning to be realised, inside and outside the OzFlux community. Other research groups within Australia (e.g. the Regional Carbon Cycle Assessment Program) and the international ecosystem exchange community (via FluxNet) are already achieving efficiency and productivity gains by routinely using OzFlux-generated data for their projects. OzFlux remains committed to further refining its data infrastructure as it continues into its second decade of flux data collection.
- Quantify ecosystem carbon and water fluxes, and their consequences in terms of primary productivity and carbon storage, can now expand from beyond the local scale to regional, ecosystem and continental-scales
- Check numbersThis is an overview of the Australian territorial carbon budget for the 1990–2011 periodThe boxes denote stores, the arrows denote fluxes. What that tells immediately is that the biosphere is accumulatig carbon at the rate of 59 TgC/year during the budget period and is much smaller than the amount of carbon that is emitted by fossil fuel burning.That number of 59 is actually the net impact of NPP and all the losses of carbon from the biosphere. The major loss is due to heterotrophic respiration (90%). Fire accounts for 6% (of NPP), LUC for about 1%, about 1% through the combined effects of logging, harvest and life stock production and a small amount is transported offshore by rivers and dust.We also want to point out that for the change of FF we see that 95 TgC/yr is released from FFburning but a much larger amount is actually shipped offshore. What that means is that our contribution to the accumulation in the atmosphere is actually dominated by our non territorial contribution, which is largely dominated by fossil fuel export.