Transcript Using Simulated OCO Measurements for Assessing Terrestrial

Using Simulated OCO Measurements
for Assessing Terrestrial Carbon Pools
in the Southern United States
PI: Nick Younan
Roger King, Surya Durbha, Fengxiang Han
Zhiling Long, Jian Chen
Introduction
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Estimated global total net flux of carbon from changes in
land use increased from 503 Tg C (1012 g) in 1850 to 2376
Tg C in 1991 and then declined to 2081 Tg C in 2000.
The global net flux during the period 1850-2000 was 156 Pg C
(1015 g), about 63% of which was from the tropics.
The global total flux averaged 2.0 Pg C/yr during the 1980s and
2.2 Pg C/yr during the 1990s (but generally declining during
that latter decade), dominated by fluxes from tropical
deforestation.
The US estimated flux is a net source to the atmosphere of 7
Pg C for the period 1850-2000, but a net sink of 1.2 Pg C for
the 1980s and 1.1 Pg C for the 1990s.
Hence, better estimates at regional level are required to
understand and reduce the uncertainties in the sink/source
estimations
Data Source: Houghton, R.A, 1999. The annual net flux of carbon to the atmosphere from the
changes in land use 1850-1990. Tellus 51B:298-313
Orbiting Carbon Observatory (OCO)
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First global, space-based measurements of
atmospheric carbon dioxide (CO2) with the
precision, resolution, and coverage needed to
characterize CO2 sources and sinks on regional
scales.
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Uncertainties in the atmospheric CO2 balance
could be reduced substantially if data from the
existing ground based CO2 network were
augmented by spatially resolved, global,
measurements of the column integrated dry air
mole fraction (X CO2 ) with precisions of
~1 ppm (0.3% of 370 ppm) (Crisp et al 2004)
Source:http://oco.jpl.nasa.gov/images/ground_track-br.jpg
Research Focus and Scope
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This research is focused on the assessment of terrestrial
carbon pools in the southeast and south-central United
States.
In particular, this investigation intends to leverage upon:
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Multiple NASA sensors
The terrestrial ecosystem model (CASA) and
Transport model GISS: GCM Model E
Undertake a Rapid Prototyping (RPC) experiment to
address the need to quantify the carbon exchange over
different ecosystems.
Test how well data from OCO observations and CO2
measurement networks constrain CO2 fluxes at modelgrid resolution.
Currently funded DOE project for leverage
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What are the current annual rates of terrestrial carbon
sequestration in each state of the region?
What's the overall contribution of terrestrial carbon
sequestration in each state of the region to mitigating its
total greenhouse gas emission?
What's the current baseline for possible carbon trading in
the region?
What's the potential of further enhancing terrestrial
carbon sequestration in the region?
What are the overall economic impacts of current and
potential terrestrial carbon sequestration on the region?
Carbon Recycling in the Future U.S. Bioenergy-Focused
Agricultural Ecosystem.
CO2 in Atmosphere
Photosysthesis
Decomposition
Total terrestrial carbon storage
and pools in the Study Area
Decomposition
Decomposition
Agricultural
products
Biomass in
Plants
Crop C: 85 Tg C,
Residue in
fields
Pasture C:
27.8 Tg C,
0.13%
Bioenergy
Waste input
Humification
/Transformation
Soil C
Housing/Furniture
C:
661 Tg C, 3.0%
Forest
C: 4454
Tg C,
Soil Organic C:
Waste input
Total Terrestrial C Storage: 21762 Tg C
Nutrients in
Irrigation
Water/Rain
Nutrients
Fertilizers
Application of Fertilizer
Irrigation/Rain
Ground
Water
Surface Runoff
Nutrients in Soil
(Bioavailable
Leaching
Plant uptake
Stable)
Surface
Water
Nitrification/Denitrification
Plant Uptake
Atmosphere
Recycling
Mineralization
Nutrients in Plant
Biomass
Agricultural products
Removal
Residue in fields
Decompostion
Gasification/evaporation
Bioenergy
Removal
Ashing
Waste/Ash
Nutrient recycling in bioenergy-focused agricultural ecosystems. Square
shapes indicate nutrient pools (i.e., sinks for C) in the bioenergyagricultural ecosystem, while arrow shapes represent processes, such as
decomposition/mineralization, ashing, evaporation,
nitrification/denitrification, plant uptake, etc.
140,000
USA Fertilizer Use
Total
120,000
1000 Ton
100,000
80,000
Nitrogen (N)
60,000
Potash
(K2O)
40,000
20,000
0
1960
Phosphate
(P2O5)
1980
2000
2020
2040
Year
Annual fertilizer consumption in U.S. since the 1960s
and the predicted fertilizers required by the proposed
US bioenergy-focused agriculture in 2030.
Science Questions
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Proposed RPC experiment seeks to address the following
questions:
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What information about carbon exchange can be obtained from
OCO high-precision column measurements of CO2?
How can we integrate top-down OCO measurements with ground
based measurements, atmospheric and terrestrial ecosystem
models to quantify carbon exchange over different ecosystems?
What are the current annual rates of terrestrial carbon
sequestration in each state of the Southeast and South-central
U.S.?
What is the current baseline in the region for possible carbon
trading?
What is the potential for enhancing terrestrial carbon
sequestration?
Rapid Prototyping Concept (RPC)
RPC Experimental Design
• Fossil Fuels
• Assimilation of aircraft
measurements, satellite
data (precipitable water,
surface winds)
Meteorology
(e.g. GOES
data analysis)
• Winds, cloud
mass fluxes,
model
Parameters
• Forward Transport Model
Transport
Model
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Vegetation Indices
Biome type
Soil properties
Weather Reanalysis
Land Surface
Model (CASA)
• 1 year spinup
• Monthly
• OCO, Networks
[CO2] OBS
1 year spinup
(2002)
• Terrestrial
CO2 surface
flux
Inversion
RPC Experimental Design
• Fossil Fuels
• Assimilation of aircraft
measurements, satellite
data (precipitable water,
surface winds)
Meteorology
(e.g. GOES
data analysis)
• Winds, cloud
mass fluxes,
model
Parameters
• Forward Transport Model
Transport
Model
• Vegetation Indices
• Biome type
• Soil properties
• Weather Reanalysis
Land Surface
Model (CASA)
• 1 year spinup
• Monthly
• OCO, Networks
[CO2] OBS
1 year spinup
(2002)
• Terrestrial
CO2 surface
flux
Inversion
NASA-CASA MODEL
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NASA-CASA (Carnegie Ames Stanford Approach) model
is designed to estimate monthly patterns in carbon
fixation, plant biomass, nutrient allocation, litter fall, soil
nutrient mineralization, and CO2 exchange, including
carbon emissions from soils world-wide.
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Assimilates satellite NDVI data from the MODIS sensor
into the NASA-CASA model to estimate
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Spatial variability in monthly net primary production (NPP),
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biomass accumulation,
and litter fall inputs to soil carbon pools
NASA-CASA Model Tasks
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Sensitivity analysis of how much NPP increase is required to
sustain the regional terrestrial carbon sink of the study area.
Net Ecosystem Productivity (NEP) (defined as Net Primary
Production (NPP) minus the heterotrophic soil respiration)
predictions would be used to infer variability in regional scale
carbon fluxes and to better understand patterns over terrestrial
carbon sinks.
The NASA-CASA model estimates of carbon products would
be calibrated with field-based measurements leveraged from
DOE project of
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Crop production,
Forest ecosystem fluxes, and
Inventory estimates of carbon pool sizes at multiple locations in south eastern
and south central United States.
NASA-CASA Model Drivers (inputs)
Soil Types (SSURGO)
•Air temperature (celsius)
•Solar radiation (w/m2 averaged over each
month)
•Deforestation
•Vegetation type
Precipitation (PRISM)
NASA-CASA model outputs for Southern US
(Note: Based on historical and 1987 data)
OCO Data Assimilation:
Techniques and Strategies
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Improved Kalman Smoother for atmospheric inversion.
 Produces estimates of fluxes at a particular time using
observations from that time step as well as observations
from subsequent times.
 Normal Kalman filter would use only past observations to
estimate fluxes at a particular time step
Ensemble Kalman filters allows for application on large
problem.
Adjoint-based descent methods for variational data
assimilation
We are exploring the possibility of developing a Support
Vector Regression-based technique for this purpose
Example Ensemble Based Assimilation
Results (synthetic data)
Ground Truth Fluxes
Observations
source
100
75
sink
Assimilation Results
50
Assimilation Errors
25
0
-25
-50
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The synthetic ground truth fluxes simulate one source area and one sink area.
The ensemble based technique was able to assimilate the observations to generate
flux estimates with small errors.
RPC Experimental Design
• Fossil Fuels
• Assimilation of aircraft
measurements, satellite
data (precipitable water,
surface winds)
Meteorology
(e.g. GOES
data analysis)
• Winds, cloud
mass fluxes,
model
Parameters
• Forward Transport Model
Transport
Model
•
•
•
•
Vegetation Indices
Biome type
Soil properties
Weather Reanalysis
Land Surface
Model (CASA)
• 1 year spinup
• Monthly
• OCO, Networks
[CO2] OBS
1 year spinup
(2002)
• Terrestrial
CO2 surface
flux
Inversion
Design of Simulation Experiments
Surface
Fluxes
CASA
Model
Transport
Model
Perturbation
With Errors
Simulated OCO
Observations
Perturbation
With Errors
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Simulated Priors
Ensemble
Based
Inversion
Estimated
Fluxes
Simulated OCO data not available from NASA yet.
Currently use data generated on our own.
Evaluation
Tasks Completed/Ongoing
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MODIS NDVI, SSURGO Soils, PRISM Precipitation datasets
acquired and conditioned for Southern United States
Initial NASA-CASA model simulations completed and analysis
of the model outputs is ongoing.
Assimilation algorithm coding is nearing completion.
Transport model simulations still in preliminary state, several
issues regarding the coupling of NASA-CASA model and the
transport model is under active research.
OSSE’s for OCO data is incomplete, looking for providers
Pursuing a OCO OSSE’s generation methodology published in
a recent issue of Journal of Geophysical Research.
Asked to participate in 2008 Carbon Cycle and Ecosystems
Joint Science Workshop to be held April 28 - May 2, 2008