Transcript Nitrogen deposition

The SANTA FE project
Jean-François Lamarque
March 31 2004
BGC Working group
Brief history
• 1st Chemistry-Climate Interactions
workshop in February 2003, Santa Fe
• Variety of speakers to discuss potential
feedbacks between chemistry (gas-phase,
aerosols, clouds) and climate
• Define a project to look at nitrogen
deposition (Sequential analysis of nitrogen
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BGC Working group
Scientific
Analysis (of)
Nitrogen (Cycle)
Towards
Atmospheric
Forcing
Estimation
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BGC Working group
Goal of the project
• Look at the evolution of nitrogen deposition
on the terrestrial biosphere during the 21st
century
• Look at the impact on the carbon uptake
• Force the climate model with the updated
CO2 forcing
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BGC Working group
Approach (1)
• Run climate models (GISS, NCAR,
UKMO) with A2 scenario to construct a
separate SSTs and climates
• Use a variety of online and offline
chemistry models (GISS, Harvard, IPSL,
LLNL, MPI-Hamburg, MPI-Mainz, NCAR,
UKMO) to calculate nitrogen deposition
(emissions are specific to each group)
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BGC Working group
Approach (2)
• Look at the impact of climate change only
and of emissions change only
• Force CLM at T31 using each nitrogen
deposition field
• Look at the spread of results as a lower
bound on the uncertainty on the results
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BGC Working group
Status (simulations available)
Model
SST
2000
GISS
GISS
X
X*
GISS
GISS
X
X*
GISS
UKMO
X
X*
NCAR
GISS
NCAR
NCAR
NCAR
UKMO
UKMO UKMO
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2050
2100
X
X
X
X,X*
X
X,X*
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X
Status (simulations in progress)
Model
SST
2000
LLNL
GISS
X
X*
LLNL
NCAR
X
X*
LLNL
UKMO
X
X*
MPI-M
GISS
X
X*
MPI-M
NCAR
X
X*
MPI-M UKMO
X
X*
UKMO UKMO
X
X*
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2050
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2100
Time table
• Compile all nitrogen deposition estimates
and write paper by summer 2004
• Perform the CLM simulations and write
paper by fall 2004
• The goal is to be available for the next
IPCC assessment
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Normalized Ndep
Dry deposition
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Wet deposition
Red
Blue
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Global ndep
Global emissions
2100
2000
Ratio (2100/2000)
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GISS
3.6
NCAR
2.6
UKMO
1.8
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Global NOx emissions (lightning)
March 31 2004
BGC Working group
Comparison with observations (EMEP)
March 31 2004
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Plots by J. Sulzman
Comparison with observations (NADP)
March 31 2004
BGC Working group
Plots by J. Sulzman
Comparison with observations
• Poor skill over European stations (on
average models tend to be lower)
• Good skill over US stations, with a
tendency to overestimate nitrogen
deposition (10%) at large values
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Analysis of Ndep totals
NCAR
UKMO
GISS
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BGC Working group
Analysis of Ndep
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Triangle
Circle
wet
dry
Red
Blue
2100
2000
Normalized Ndep
Global total ndep
Global emissions
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BGC Working group
Conclusions
• Global increase in Ndep tends to closely follow
the increase in emissions, especially in the NCAR
model. Unclear if the increase in other models
from climate change is statistically significant
• What is happening to GISS_2100?
• The hydrological cycle (as identified by lightning
and wet deposition) in the GISS model seems to
have a stronger response to climate change than
other models, except with the NCAR SSTs
March 31 2004
BGC Working group