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COS: A new tracer to constrain photosynthetic CO2 fluxes
Dan Yakir1,
Max Berkelhammer2, Hulin Chen2 J. Miller3 1Environmental Sciences and Energy Research, Weizmann Institute
NOAA-GMD, Boulder, 3CIREES, UC Boulder
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A greatest sources of uncertainty for future climate predictions Is the response of the global carbon cycle to climate change
…our mass balance analysis shows that net global carbon uptake has increased significantly by about 0.05 Gt C per year and that g lobal carbon uptake doubled, from 2.4±0.8 to 5.0±0.9 Gt per year between 1960 and 2010… Ballantyne et al 2012
NEE = GPP + Re
GPP Re
Net CO2 flux
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A major limitation: we cannot measure photosynthesis above the leaf scale
Soil uptake (74-180)
Anthropogenic, direct/indirect (90-266)
Direct COS (110-190) Indirect CS2, DMS (149-330)
Unknown (~600)
Stratosphere COSàSO2 OH uptake (82-110)
Global COS Budget (Gg S a-1; Kettle et al., 2002; Montzka et al., 2007; Berry et al., 2013 )
Mean atmospheric concentration ~500 ppt!
Leaf uptake (730-1500)
?
Global ocean
BB, wetland (81-119)
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COS Uptake by Leaf During Photosynthesis
COS
CO2
COS and CO2 are taken up through leaf stomata during
photosynthesis
CO2
COS
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Exiting new technological advances (Quantum cascade, mid IR lasers, Mobile lab….
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GPP
Ra
NPP
CO2 into leaves
Rh
NEE COS
Changes in ratio of COS to CO2 uptake across scales
Soil exchange? ARU=COSseasonal_drawdownCO2sessonal_drawdown
![CO2][COS]
~1.6±0.2
~Constant across species and conditions
Near zero
LRU
COS into leaves
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LRU = AcosAco2
[CO2]a[COS]a
GPP =Fcos [CO2a][COSa]! 1LRU
GPP/NEE= 1.9 to 2.2
200
300
400
500
600
2000 2001 2002 2003 2004
Mix
ing
ratio
(pp
t)
mlokumnwrlefhfmbrwaltbrw, monthlykum, monthlyhfm, monthly
Montzka et al., 2007
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The signature of the Terrestrial Biosphere
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y = 5.77x + 0.00R2 = 0.89
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
-0.01 0.00 0.01 0.02 0.03 0.04 0.05 0.06
CO2 (Spring - Fall) / mean
COS
(Spr
ing
- Fal
l) / m
ean
LEF
ALT
BRW
NWR
MLO
KUM
CGO
HFM
MHD
SPO
SMO
Signature of GPP: COS/CO2 seasonal draw-down
Montzka et al., 2007 Asaf et al., 2013
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The atmospheric COS/CO2 “continuum”
NH continental sites
NH coastal sites
Leaf LRU
C3 max
C4 max
SH (ocean)
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Terrestrial &agricultural sites: Wisconsin; Iowa; S. Carolina ARU approaches LRU C4 effects
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Mauder & Eder, unpublished
Ceilometer, two consecutive days
Wind Lidar:
Perspective from the Planetary Boundary Layer (PBL)
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Perspective from canopy air measurements: Diurnal surface concentration measurements
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Linking events in the surface layer to the PBL
Equations for both CO2 and COS with measured NEE and surface Cs solved for k and Ctrop
• COS is a useful tracer of CO2 exchange with the terrestrial ecosystems and will add a powerful tool to a very limited arsenal..
• There is no alternative “observational” means to directly
estimate GPP on global scale (new sun fluorescence is also developing)
• Incorporating the use of several tracers controlled by
different processes (such as COS and CO2 and its stable isotopes) provide additional insights to the biosphere response to global change
Conclusions
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Thank you