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Helen Cleugh and Eva van Gorsel Near-real-time measurement of CO 2 , water and energy fluxes: Determining the best available estimates of continental carbon and water fluxes
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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

Dec 24, 2014

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Page 1: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

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

Page 2: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

“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

Page 3: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

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

Page 4: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

Logo

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

ETQ

Page 5: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

Logo

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

Page 6: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

OzFlux Data Path

OzFluxQC/post-processing

Page 7: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

time scales involved in the land – air exchanges of carbon and water

after M.Williams et al., www biogesciences.net/t/1341/2009/

Page 8: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

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

Page 9: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

time and length scales covered

Courtesy P. Isaac

Seconds

Minutes

Tim

e

Scale

10-3 10-2 10-1 100 101 102

103

104metres

Length Scale

10-1

100

101

102

103

104

105

106

Leaf Canopy

Patch Region

Days

Yearsseconds

Leaf LevelObservations

Flu

x To

wer

Aircraft Fluxes

Aircraft Remote Sensing

Satellite Remote Sensing

Land Surface Model

GCM

Plot LevelObservations

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.

Page 10: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh
Page 11: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

Modelling Framework BIOS2

Page 12: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

Observations for BIOS2 constraints and evaluation

Viney-Vaze unimpaired catchments

OzFlux sitesInventory sites (Injune, Kioloa)Above-ground phytomass (VAST+Raison+Hilbert)Above-ground litter (VAST)Litter-fall (VAST)Soil carbon (VAST)

Page 13: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

Multiple constraints on Australian terrestrial Net Primary Production: Eddy flux data provide the tightest constraint

error bars = uncertainty from propagated parameter uncertainties (1s)

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

Page 14: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

A reality check - comparing OzFlux measured ET, GPP and BIOS2 simulations

Monthly

Monthly

Annual

Annual

Page 15: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

BIOS2 evaluation: comparison with Viscarra Rossel observation-based soil carbon

Page 16: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

Aust

ralia

n CO

2 Bud

get

Haverd et al. 2013 a, b. Biogeosciences

Page 17: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

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

Page 18: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

OzFlux 2013Sites 28

Accounts 96Site-years 62

11 years of ecosystem breathing at Tumbarumba, NSW

Page 19: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

Thank

You and

Ques

tions

AcknowledgementsTERN HQ

• Tim, Stuart, Guru and the teamOzFlux

• Ray Leuning – Founding OzFlux Director• OzFlux Steering Committee: Mike Liddell,

Lindsay Hutley, Jason Beringer, Wayne Meyer, Alex Held, Peter Isaac

• OzFlux PIsCollaborators

• Vanessa Haverd• FluxNet

Page 20: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

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

Page 21: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

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)

OzFluxAnd TERN

Australian ecosystem and climate science

Page 22: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

3. Connections: Global

FLUXNET

GEWEX Future Earth: WCRP - ESSP

NEON

OzFluxAnd TERN

Global ecosystem, climate and Earth system science

Page 23: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

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”

Page 24: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

…. the TERN infrastructure “ecosystem”

Knowledge of ecosystem exchange of carbon, water &

energy

Vegetation typeGPP

Veg indices (NDVI, EVI)Leaf area index

FireCanopy properties .....

CO2 and H2O FluxesRadiation

Meteorology

Site characteristicsBiomass

Soil carbon & nutrients

Leaf-level photosynthesis

Data assimilation and integration into modelling applications

AusPlots and Australian Supersites Network

OzFlux Network

eMASTAusCover

Page 25: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh

abstractThe 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.

Page 26: Near real-time measurement of CO2, water and energy fluxes: determining the best available estimates of continental carbon and water fluxes_Cleugh