Helen Cleugh_Near-real-time measurement of carbon dioxide, water and energy fluxes: determining the best available estimates of ecosystem carbon and water fluxes at continental scales
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TERN Ecosystem Surveillance Plots Kakadu National Park
Helen Cleugh_Near-real-time measurement of carbon dioxide, water and energy fluxes: determining the best available estimates of ecosystem carbon and water fluxes at continental scales
1. Near-real-time measurement of CO2, water
and energy fluxes: Determining the best
available estimates of continental carbon and
water fluxes
Helen Cleugh, Eva van Gorsel and Vanessa Haverd
CSIRO Marine and Atmospheric Research
2. Some climate policy questions and
the research needed to provide the
answers
What is the role of natural land and ocean sinks in
sequestering greenhouse gas (GHG) emissions and what will
happen to these sinks in the future?
• Carbon cycle observations that track the uptake and release of
greenhouse gases in land, air and oceans
• How does climate change and variability affect Australia’s carbon
budget (sources and sinks; anthropogenic and biogenic)?
• Climate models (such as ACCESS) include coupled carbon and water cycle
3. Some climate policy questions and
the research needed to provide the
answers
How can we use our natural land sinks to mitigate Australia’s
GHG emissions?
What is the impact of natural disturbance regimes; how are
they changing?
• Investigate how climate and land management affect the stability of
Australia’s land-based carbon sinks
• How will carbon dioxide fertilisation affect Australian vegetation?
• Ensuring global and regional climate simulations represent Australian
terrestrial ecosystem processes
4. 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”
6. AusPlots and
OzFlux Australian
Network Supersites Network
Site characteristics
CO2 and H2O Fluxes Biomass
Radiation Soil carbon & nutrients
Meteorology
Leaf-level photosynthesis
AusCover eMAST
Data assimilation and
Vegetation type
integration into
GPP
Veg indices (NDVI, EVI)
Knowledge of modelling applications
Leaf area index ecosystem exchange
Fire of carbon, water &
Canopy properties .....
energy
…. the TERN infrastructure “ecosystem”
7. OzFlux: a continental network of flux
stations to measure ecosystem fluxes
using nationally-consistent approaches
Flux towers measuring vineyard
and forest CO2 and water H
fluxes
ET
Q • CO2 (NEE) and water use (ET)
• Energy: Radiation (Q) and heat (H, G)
Q
NEE • Spatially-averaged at canopy-scale
• Continuous: hourly to multi-annual
G
10. OzFlux: carbon and water fluxes
available via a data portal for a range of
Australian climates and ecosystems
See OzFlux Data
Portal demo. by
Peter Isaac this
afternoon
11. What is Australia’s net carbon balance?
• How does climate change and variability affect
Australia’s carbon budget (sources and sinks;
anthropogenic and biogenic)?
• How much water is required for an ecosystem to
sequester CO2?
12. Determining Australia’s net biogenic carbon & water
balance by combining models and observations
• Haverd et al (2012) Using multiple observation types to
reduce uncertainty in Australia’s terrestrial carbon and water
cycles, Biogeosciences Discuss., 9 (2012)
• BIOS2 modelling environment
• Multiple observations
13. BIOS2 Model Environment
(Haverd et al, 2012)
BIOS2 = CABLE-SLI-CASAcnp in AWAP operational framework
CABLE = Community SLI = Soil-Litter-Iso CASAcnp =
Atmosphere-Biosphere-Land • Soil hydrology, evaporation Biogeochemical model
Exchange model • Soil & plant C, N, P
Haverd et al. (2011)
• Water, energy, carbon fluxes dynamics
Wang et al. (2011) Wang et al. (2007)
AWAP = Australian Water Availability Project
• Meteorology and soil data
• Continental processing framework
• Model-Data Fusion
Raupach et al. (2009)
14. Determining Australia’s net biogenic carbon & water
balance by combining models and observations
• Haverd et al (2012)
• BIOS2 modelling environment = CABLE + CASAcnp + SLI
• Multiple data sets:
• OzFlux carbon, water and energy fluxes
• Streamflow from gauged catchments
• Litterfall (leaf NPP)
• Carbon pools (above ground biomass, soil carbon)
15. Including OzFlux data to constrain
BIOS2 simulations of NPP (Net Primary
Production) for Australian continent
Prior estimate
Eddy fluxes
Streamflow
Litterfall
Eddy fluxes + Litterfall
error bars = uncertainty
Streamflow + Litterfall from propagated parameter
Streamflow + Eddy fluxes uncertainties (1 std. dev.)
Eddy fluxes + Litterfall + Streamflow
0 1 2 3 4
Net Primary Production (NPP) =y2.1 GT carbon per year
NPP (GtC )
-1
Including OzFlux flux data yields the greatest reduction in
uncertainty in NPP and ET
16. A reality check - comparing OzFlux
measured GPP and BIOS2 simulations
OzFlux = ensemble
annual cycle
BIOS2 = long-term
mean annual cycle
17. A reality check - comparing OzFlux
measured ET and BIOS2 simulations
OzFlux = ensemble
annual cycle
BIOS2 = long-term
mean annual cycle
18. A reality check - comparing OzFlux
measured ET and BIOS2 simulations
Monthly Annual
Monthly Annual
19. Australia’s water and carbon balance
from BIOS2, constrained by data
Soil Evaporation
• Energy, carbon, water budgets
• 1990 – 2009 (monthly)
• 5 km resolution
• Using BIOS2 (CABLE + SLI + CASAcnp)
Total NPP
Transpiration
20. NPP (g m-2 d-1)
3pg
3 i AussieGrass
BiosEquil
Century
2 CenW
dLdP
Miami-oz
12 mean NPP estimates 1
Miami
Olson
for Australia RFBN
TMS
(Roxburgh et al 2004) 0 Vast
ET (mm y-1)
ii AWAP
7 mean ET estimates for 1000 AWRA
Guerschman
Australia NDTI
etlook
(King et al 2012) MODIS
500
0
Australia
Savanna
Tropics
Warm Temp
Cool Temp
Mediterr
Desert
1 2 3 4 5 6 A
21. Concluding Comments (1)
• Climate mitigation and adaptation policy drivers requires a
capability to determine carbon and water budgets at ecosystem
to continental scales
– TERN provides model – data research infrastructure needed
– OzFlux + AusCover + Supersites + AusPlots + Soils
• 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
22. Concluding Comments (2)
• Insights into the dynamic
carbon and water budgets
for the Australian
continent, e.g.:
– Large inter-annual
variability in NPP driven by
variation in available
moisture
– And larger than
anthropogenic greenhouse
gas emissions
Hinweis der Redaktion
Q1: Under the Mitigation science deliverables
Q2: Under the Mitigation science deliverables
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
Shows range in climates
Shows range in climates
Currently, there is significant uncertainty about Australia’s net primary productivity - the difference between carbon that is taken up by vegetation from the atmosphere and carbon respired by plants and microbes. There is corresponding significant uncertainty about rates of water loss through transpiration from plants and evaporation from soil and water bodies. This obviously limits our understanding of and capacity to manage Australia’s interlinked carbon and water cycles.
Note that each obs. type has different space and time scales
Currently, there is significant uncertainty about Australia’s net primary productivity. There is corresponding significant uncertainty about rates of water loss through transpiration from plants and evaporation from soil and water bodies. This obviously limits our understanding of and capacity to manage Australia’s interlinked carbon and water cycles. Long-term continental Carbon balance (RHS) using BIOS2, constrained by data including OzFlux dataPrior parameters and their uncertainties lead to a continental NPP of 2.5±1.1 PgCyr−1, while the estimate constrained by all three data sets is2.1±0.4 GtCyr−1,->including eddy fluxes reduces uncertainty considerably (strongest effect). The impact of each of three data sets (leaf –NPP (litter-fall), streamflow and eddy flux data) and combinations thereof on the long-term mean Australian continental NPP estimate and its uncertainty. Each data set individually leads to a reduction in uncertainty compared with the prior estimate, although with quite different values, reflecting possible biases in the model and/or observations for the particular observable. The estimates are more convergent when 2 data sets are used simultaneously, and the estimate constrained by all three is a compromise between the results obtained using each data set individually.The error bars in Figure 3 indicate that eddy flux data provide a stronger constraint than leaf-NPP, even though leaf NPP observations more widely distributed (Figure 2). This reflects the high precision of the eddy flux measurements, compared with disparate litterfall observations which do not share a common methodology and are subject to large errors from fine scale heterogeneity. Long-term evaporation from streamflow provides a relatively weak constraint because in most regions of Australia, it is largely driven by rainfall (continentally, evaporation accounts for 90% of precipitation).
Verification – using allConstraints - Tumba, HS and Daly’s – see map at Slide 20
Long-term continental water balance (LHS) and Carbon balance (RHS) using BIOS2, constrained by data including OzFlux data
Here, the top two panes of the previous slide (NPP and ET) are shown with all elements greyed out. Superimposed in colour on the NPP pane are the various Roxburgh results. Superimposed on the ET pane are most of the WIRADA ET estimates. The old CABLE results from WIRADA will be removed for publication. Also left out of the WIRADA results are those of Yongqiang, which have some problems. All ET results are for the period Jan 2000-Dec 2005, except etlook which is for 2002/07-2005/06.
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.