Australia’s National Science Agency

Using satellite observations to model net carbon dioxide
emissions from AFOLU (REgional Carbon Cycle Assessment andProcesses (RECCAP) under the Global Carbon Project
Yohanna Villalobos, Pep Canadell, and the Australasia RECCAP2 team

IPCC TFI Expert Meeting on Use of Atmospheric Observation Data in Emission Inventories
5 – 7 September 2022
Presenter: Yohanna Villalobos
Tuesday, 6 September 2022

Geneva - Switzerland

What is RECCAP-2?
•RECCAP-2 is a global assessment to develop regionaland national (for big countries) carbon, methane andnitrous oxide budgets.

•To contribute to the Paris Agreement global stocktake
and tracking towards net zero emissions ofanthropogenic and natural GHG sources and sinks.

•To quantify and further constrain anthropogenic
greenhouse gas emissions and thus support theimprovement of National greenhouse gas inventories(NGHGIs).

Figure 1: The RECCAP2 budget considers ten land regions and five ocean regions that together
cover the entire globe (Kondo et al., 2021)

Two-tier approach for national/regional GHG balance
Tier 2Tier 1

Global Products

National/Regional-Specific Products

Regional fluxes
from global
atmospheric inversions

Regional

atmosphericinversion+

Higher resolution

Low resolution
Global prior flux

Regional observations
and prior fluxes

Regional Carbon Balance

Regional cuts
from global
biosphericmodeling
Low resolution

GCP, RECCAP1+

Regional cuts
from global
data-flux
products+

National model
applications(continental,basin, biome,land use change,others)+

National
specific
observations(fluxes, remotesensing, LULUCF
forest inv., others)

How we compare AFOLU/LULUCF from NGHGI with inversions?
National GHG inventory (NGHGI)(IPCC guidelines, 2006, 2019)

National/Regional
Carbon Budget
Agriculture, Forestry
and Other Land Use(AFOLU/LULUCF)

In Australia, all lands are considered managed lands(except 8 per cent from desert areas).

National/Regional

Atmospheric Inversion
Satellite-based inversion
Provides best estimate of net C balanceNational/Regional

Global Atmospheric Inversions

Atmospheric Inversion
Satellite-based inversion
Provides best estimate of net C balance

Spatial &temporal resolvedfluxes

Prior fluxes for assimilation

National/Regional application of

National/Regional

Biospheric
Modeling

Carbon Budget
Comprehensive C balance
Anthropogenic and natural fluxes(NGHGI, biospheric modeling, otherdata & modeling,

Parameterized and benchmarked with datafrom the C budget (w/NGHGI), and other fluxes
and observations

Australia carbon integrated system

Regional Australia carbon Budget (2010-2019) (Units Tg C yr-1)- Work in Progress Atmosphere∆C = 145.06 (territorial) + 387.22 (non-territorial)
304.95

7.33

16.66

Non-Territorial
emissions

11.84

water-airfluxesNEE

Riverevasion

6.05

Lakes
evasionExportinto estuaries
12.73

Coastalwetlands

0.16 Estuaries

riversTidal | deltas DOC: 2.21
POC: 2.30
Lagoons

Mangroves
Tidal marshes
Seagrasses∆C burial
1.18

2037.49 108.95

Net primary
productivity
Heterotrophic
respiration Fire

Lakes
/reservoir

-2.81

0.66

Land use
Change0.01

Waste

Agriculture

6.45∆C burial
0.26

Fjords∆C burial
4.09

2130.99

Inland waters
22.66

Terrestrial
Ecosystem

Logging∆C = -59.41

harvest

DIC: 4.16

LOAC

12.81
4.18
Live
produce

4.55

Wood
decay

7.72

Weathering CO2
Crop
uptakeConsumption
Livestock
Consumption

Wood∆C = 1.23∆C = 304.95

Territorial Fossil
fuel Emissions

Fossil fuel1.04

∆C = -396.15

GeologicalLivestock
BiologicalProducts

5.16Non-Territorial emissions

109.92∆ ClithoC
dissolved

CropcropExport

Transfer to theopen ocean

3.12

4.02

Livestock Wood
export Export
0.16

0.67

Fossil fuel export
286.23

Australia regional inversion (2015-2019)
WRF model(meteorologicaldata)

Initial andBoundaryconditions(CAMS)CMAQ
Forward model

Updatexminimizer

Posterior fluxes

OCO-2 Satellite data
Land nadir and glint(version 9) (y)Updated knowledge ofthe prior fluxes

Bottom-up approach
2. Regional
CABLE Biospheremodel(BIOS3model*environment)
Fossil fuel emissions(EDGAR and ODIAC)

The total column-averagedmole fractions of carbon
dioxideSimulated CO2
concentration

UpdateCost Function
J(x)7Best estimate of theNBP emission andtheir uncertainties
Prior C fluxes (x)Fire emissions(GFED dataset)
Ocean Emissions(CAMS inversion)

Adjoint of CMAQ model
Backward model𝛁𝛁J(x)
UpdateGradient of the costfunction

The importance of prior fluxes in the regional inversion

Figure 1. Net Biome Production (NBP). Positive indicates a terrestrial carbon sink
(Teckentrup et al., 2021).

Long-term mean 2015-2019

The long-term mean of our posterior terrestrial CO2 flux indicate that Australia was acarbon sink of -0.46 +- 0.08 PgC y-1 compared to the prior flux estimate which was
0.11 +- 0.20 PgC y-1 (excluding fossil fuel emissions). (Villalobos et al., 2022)

9

Climatological seasonal carbon cycle 2015-2019

Climatological seasonal cycle of prior (orange points) and posterior (blue points) terrestrial carbon fluxes (2015–2019). The dashedorange and blue lines represent a smooth line for the prior and posterior fluxes respectively.

Climatological GPP 2015-2019

Climatological seasonal cycle of prior (orange points) and posterior (blue points) terrestrial carbon fluxes (2015–2019). The dashedorange and blue lines represent a smooth line for the prior and posterior fluxes respectively. (Villalobos et al., (2022).

Validation with independent data
• The Total Carbon Column Observing Network (TCCON)
records direct solar spectra in the near-infrared spectral
region (red dots).

• In-situ measurements (blue dots)
12

Validation

TCCON observations

in-situ observations

Comparison:
Regional OCO-2, Global OCO-2 MIP, TBM (prior, CABLE) and FluxCom

Comparison between monthly mean posterior (blue line), prior (orange line), FLUXCOM ensemble mean (green line), OCO-2 MIPensemble (black line) carbon fluxes, and the monthly carbon fluxes from the nine models that participate in OCO-2 MIP: AMES,PCTM, CAMS, CMS-Flux, CSU, CT, OU, TM5-4DVAR, and UT (in PgC yr−1).

OCO-2 inversion results against what is reported in the LULUCF From
Australian NGHGI (2015-2019)

Reconciling OCO-2 inversion results with LULUCF From Australian NGHGI
1. Sort out any definitional inconsistencies and system boundaries on what is included and not in eachof the two approaches, and identify any clear missing fluxes, particularly natural fluxes which might
not be included in the NGHGI.
2. Assess how sinks and sources are created from the strong inter-annual climate variability in Australia,
and therefore not part of the long-term trend driven by direct human activities.
3. Implications from using static empirical growth models, yield curves, and biomass maps in the NGHGI
versus processes modeling or forest inventory approaches that include the indirect effects of achanging climate and atmospheric CO2 (the CO2 fertilization effect).
4. As the NGHGI focuses primarily on anthropogenic forest-to-no-forest (and back again) conversions,carbon sinks/sources from arid and semi-arid ecosystems could be missing in the inventory.
5. What do we learn from any remaining gaps once the above has been sort out? Have we identified
new sources or sinks, key processes, hot spots, etc?

National/Regional

Global Atmospheric Inversions

Atmospheric Inversion
Satellite-based inversion
Provides best estimate of net C balance

Spatial &temporal resolved
fluxesPrior fluxes for assimilation

National/Regional application ofNational/Regional

BiosphericModeling

Carbon Budget
Comprehensive C balance
Anthropogenic and natural fluxes(NGHGI, biospheric modeling, otherregional observations & modeling,

Parameterized and benchmarked with datafrom the C budget (w/NGHGI), and other fluxes
and observations

Australia carbon integrated system

RECCAP2-Australasia contributions• Atmospheric Inversions & land surface modellingin Australia
•
•
•
•
••
•
•

Yohanna Villalobos, CSIRO, coordinating lead authorPeter Rayner, University of Melbourne.
Peter Briggs, land surface modeling, data analysisIan Harman, land surface modeling
Juergen Knauer, CSIRO, land-surface modeling
Ben Smith, WSU, CABLE-BIOS
Pabrir Patra (CO2, NO2 and CH4)
Hanqin Tian, and Naiqing Pan (N2O),• Atmospheric Inversions & land surface modellingin NZ••••

Liz Keller, GNS, New Zealand
Timothy W. Hilton, GNS New ZealandBeata Bukosa, NIWA
Sara Mikaloff-Fletcher, NIWA

LOAC (Land to ocean aquatic continuum )• inland waters:• Ronny lauerwald• Coastal ecosystem:• Judith Rosentreter, Yale University• Thomas Wernberg, UWA: blue carbon, kelp forest• Oscar Serrano, ECU: blue carbon, seagrass• Shelf fluxes• Laure Resplandy, Princeton University• Flux Inventories:• DAWE, DISER (Australian LUC, Agriculture, Fossil fuel)• Yohanna Villalobos, CSIRO, coordinating lead author• Pep Canadell, CSIRO, coordinating lead author• Future projections:• Tilo Ziehn, CSIRO: CMIP6, Earth System modelling• Liz Keller, GNS, New Zealand