implications of observed surprisingly high atmospheric oxidizing capacity over tropical forest: the...
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Implications of observed surprisingly high Implications of observed surprisingly high atmospheric oxidizing capacity over tropical atmospheric oxidizing capacity over tropical
forest: the GABRIEL Campaignforest: the GABRIEL Campaign
Implications of observed surprisingly high Implications of observed surprisingly high atmospheric oxidizing capacity over tropical atmospheric oxidizing capacity over tropical
forest: the GABRIEL Campaignforest: the GABRIEL Campaign
Laurens GanzeveldLaurens Ganzeveld1,21,2, Tim Butler, Tim Butler22, John Crowley, John Crowley22 , Terry Dillon , Terry Dillon22, Gunter Eerdekens, Gunter Eerdekens2,32,3, Horst , Horst FischerFischer22, Hartwig Harder, Hartwig Harder22, Rainer Königstedt, Rainer Königstedt22, Dagmar Kubistin, Dagmar Kubistin22, Mark Lawrence, Mark Lawrence22, Monika , Monika
MartinezMartinez22, Bert Scheeren, Bert Scheeren44, Vinayak Sinha, Vinayak Sinha22, Domenico Taraborrelli, Domenico Taraborrelli22, Jonathan Williams, Jonathan Williams22, Jordi , Jordi Vilà-Guerau de ArellanoVilà-Guerau de Arellano11, and Jos Lelieveld, and Jos Lelieveld22
11Department of Environmental Sciences, Wageningen University and Research Centre, Wageningen, NetherlandsDepartment of Environmental Sciences, Wageningen University and Research Centre, Wageningen, Netherlands22 Department of Atmospheric Chemistry, Max-Plank Institute for Chemistry, Mainz, Germany Department of Atmospheric Chemistry, Max-Plank Institute for Chemistry, Mainz, Germany
33Research Group Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Antwerp, BelgiumResearch Group Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Antwerp, Belgium44European Commission Joint Research Centre, Institute for Environment and Sustainability, Climate Change Unit, Ispra, Italy.European Commission Joint Research Centre, Institute for Environment and Sustainability, Climate Change Unit, Ispra, Italy.
Laurens GanzeveldLaurens Ganzeveld1,21,2, Tim Butler, Tim Butler22, John Crowley, John Crowley22 , Terry Dillon , Terry Dillon22, Gunter Eerdekens, Gunter Eerdekens2,32,3, Horst , Horst FischerFischer22, Hartwig Harder, Hartwig Harder22, Rainer Königstedt, Rainer Königstedt22, Dagmar Kubistin, Dagmar Kubistin22, Mark Lawrence, Mark Lawrence22, Monika , Monika
MartinezMartinez22, Bert Scheeren, Bert Scheeren44, Vinayak Sinha, Vinayak Sinha22, Domenico Taraborrelli, Domenico Taraborrelli22, Jonathan Williams, Jonathan Williams22, Jordi , Jordi Vilà-Guerau de ArellanoVilà-Guerau de Arellano11, and Jos Lelieveld, and Jos Lelieveld22
11Department of Environmental Sciences, Wageningen University and Research Centre, Wageningen, NetherlandsDepartment of Environmental Sciences, Wageningen University and Research Centre, Wageningen, Netherlands22 Department of Atmospheric Chemistry, Max-Plank Institute for Chemistry, Mainz, Germany Department of Atmospheric Chemistry, Max-Plank Institute for Chemistry, Mainz, Germany
33Research Group Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Antwerp, BelgiumResearch Group Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Antwerp, Belgium44European Commission Joint Research Centre, Institute for Environment and Sustainability, Climate Change Unit, Ispra, Italy.European Commission Joint Research Centre, Institute for Environment and Sustainability, Climate Change Unit, Ispra, Italy.
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OH [1e6 molec. cm-3]
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SCM, 3-10
SCM, 4-10
De GABRIEL campagne (Guyana’s 2005)
Lelieveld, J., Butler, T.M., Crowley, J., Dillon, T., Fischer, H., Ganzeveld, L., Harder, H., Kubistin, D., Lawrence, M.G., Martinez, M., Taraborrelli, D., and Williams, J., Atmospheric oxidation capacity sustained by a tropical forest, Nature, doi:10.1038/nature06870, 2008.
Observations of OH concentrations in the PBL much higher than simulated in any state-of-the-art atmospheric chemistry and transport model.
Surprisingly high atmospheric oxidizing capacity over tropical forest: the GABRIEL CampaignSurprisingly high atmospheric oxidizing capacity over tropical forest: the GABRIEL Campaign
OH recycling in isoprene oxidation product reactions
urban (U.S.)
remoteagricultural
(U.S.)
Maritime (pacific)
Courtesy: Franz Meixner, from: Chameides
O3 p
roduct
ion,
OH recy
clin
g
Oxidizi
ng cap
acity
The OH Radical: the Atmosphere‘s detergentThe OH Radical: the Atmosphere‘s detergent
OH HO2
recyclingsource
sinkNMHC
CO, CH4, CH2O
CO2, H2O
CH2Ohν
H2O2
HO2
NO2
NOhν
NO2
O3 + hvO(1D) + H2O
Primary OH Formation O3 + h → O2(
1Δ) + O(1D)
O(1D) + M → O(3P) + M
O(3P) + O2 + M → O 3 + M
O(1D) + H2O → 2 OH
OH Recycling
HO2 + NO → OH +NO2 (high NOx)
HO2 + O3 → OH + 2O2 (low NOx)
Wet tropical forest
Oxidizing capacityOxidizing capacity
NOx: reactive nitrogen oxides NO, NO2, NO3, etc. VOC’s (or NMVOC): Volatile Organic Compounds, e.g., isoprene, acetone etc.
Courtesy: Jos Lelieveld
Oxidizing capacityOxidizing capacity
Low NOx, high natural VOC’s
Major influences on tropospheric OHMajor influences on tropospheric OH
Forcing Mechanism Response
NOx ↑ O3 formation, OH recycling OH ↑
H2O ↑ H2O + O(1D) → 2OH OH ↑
CH4 ↑ CH4 + OH → products OH ↓
CO ↑ CO + OH → products OH ↓
NMHC ↑ NMHC + OH → products OH ?
Clouds ↑ light scattering, multiphase chemistry OH ?
Courtesy: Jos Lelieveld
How will deforestation affect atmospheric chemistry How will deforestation affect atmospheric chemistry and climate through the modification of the exchange and climate through the modification of the exchange of moisture, energy and matter and GHG lifetime?of moisture, energy and matter and GHG lifetime?
Oxidizing capacityOxidizing capacity
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OH [1e6 molec. cm-3]
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SCM, 4-10
Note the large difference between simulated and observed OH concentrations < 1500m
This points at a problem in atmospheric chemistry models in the representation of boundary layer chemistry and in particular of tropical forest exchanges
It explains why large-scale scale chemistry models overestimate tropical isoprene concentrations using state-of-the art biogenic emission algorithms
Factor 5-10 higher OH concentraties in tropical BL 10-20% decrease in CH4 lifetime
The other cleansing mechanism; wet deposition
GABRIEL flight tracksGABRIEL flight tracksGABRIEL flight tracksGABRIEL flight tracks
Atmospheric Chemistry over tropical forest: Gabriel flight tracksAtmospheric Chemistry over tropical forest: Gabriel flight tracks
Single-Column Chemistry-Climate modelSingle-Column Chemistry-Climate modelSingle-Column Chemistry-Climate modelSingle-Column Chemistry-Climate model
Multi-layer canopy model for trace gas exchangesMulti-layer canopy model for trace gas exchangesCBM4+ terpene chemistry, sulfur, CH3CL and RnCBM4+ terpene chemistry, sulfur, CH3CL and Rn
Multi-layer canopy model for trace gas exchangesMulti-layer canopy model for trace gas exchangesCBM4+ terpene chemistry, sulfur, CH3CL and RnCBM4+ terpene chemistry, sulfur, CH3CL and Rn
GABRIEL flight tracks and SCM GABRIEL flight tracks and SCM trajectory for lagrangian experimenttrajectory for lagrangian experiment
GABRIEL flight tracks and SCM GABRIEL flight tracks and SCM trajectory for lagrangian experimenttrajectory for lagrangian experiment
4.5N, 45W-60W01-10 00:00 - 04-10 00:00 UTCΔT=60 seconds, 6.5 m s-1 (zref =1250m), ΔX = ~ 300 m
Atmospheric Chemistry over tropical forest: SCM simulationsAtmospheric Chemistry over tropical forest: SCM simulations
Ganzeveld, L., and J. Lelieveld, Impact of Amazonian deforestation on atmospheric chemistry, Geophys. Res. Lett., 31, L06105, doi:10.1029/2003GL019205, 2004.
Sources of Reactive Trace Gases: NOSources of Reactive Trace Gases: NOxx-VOC-VOC
Simulated soil NO emissions and canopy NOx flux
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Time [dd:hh]
F-N
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ole
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-1]
Fsoil
F-canopy top
Lab Flux
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Time [dd:hh]
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C5H
8 m
-2 h
r-1]
MEGAN
G95
Simulated isoprene emissions for Gabriel domain
Inferred isoprene emission flux from dC/dt in C5H8 and MVK+Methac. conc and PBL height
Extensive evaluation of BVOC and NOxexchanges regime
Ganzeveld, L., Eerdekens, G., Feig, G., Fischer, H., Harder, H., Königstedt, R., Kubistin, D., Martinez, M., Meixner, F. X., Scheeren, B., Sinha, V., Taraborrelli, D., Williams, J., Vilà-Guerau de Arellano, J., and Lelieveld, J., Surface and Boundary Layer Exchanges of Volatile Organic Compounds, Nitrogen Oxides and Ozone during the GABRIEL Campaign, Atmos. Chem. Phys., 8, 6223–6243, 2008.
Simulated OH source and sink terms over tropical forestSimulated OH source and sink terms over tropical forest
Simulated chemical sources and sinks of OH over land, day2, 18UT
OH –C5H8
jO3
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day3, O3 lev13-14 nudged day3, O3 lev13-14, J=1.2xJ
Simulated versus observed OH concentrations over land
PBL
Representation of jO3 in FT is explaining a lot of discrapency but in PBL there is still a large underestimation: too large sink or missing source of OH in PBL?
OH concentrations in canopy and PBL
Elevated nocturnal and Elevated nocturnal and early morning OHearly morning OH
sesquiterpene concentrations in canopy and PBL
OH sources: VOC ozonolysisOH sources: VOC ozonolysis
Considering this potential source of OH improves the simulations of OH and isoprene in the canopy and surface layer but not aloft!
Needed: VOC being destroyed by ozonolysis (not by OH), producing efficiently OH and living long enough to be transported higher up in the
PBL (τ ~30 min.)
Compound τOH[OH]=2e6 cm-3
τO3
[O3]=7e11 cm-3
OH yield 2-generation Product with Double Bond
isoprene 1.4 h 1.3 day 0.19-0.44
-pinene 2.6 h 4.6 h 0.70-0.93
-pinene 1.8 h 1.1 day 0.35
2-carene 1.7 h 1.7 h
3-carene 1.6 h 11 h 0.86-1.06
limonene 49 min 2.0 h 0.67-0.86 x
sabinene 1.2 h 4.8 h 0.26-0.33
myrcene 39 min 50 min 0.63-1.15 xx
cis/trans-ocimene 33 min 44 min 0.55-0.63 xx
-phellandrene 27 min 8 min ?
-phellandrene 50 min 8.4 h 0.14 x
-terpinene 23 min 1 min 0.38
-terpinene 47 min 2.8 h 0.81
terpinolene 37 min 13 min 0.74-1.03 x
-caryophyllene 42 min 2 min 0.06 x
-cedrene 2.1 h 14 h
-copaene 1.5 h 2.5 h
-humulene 28 min 2 min ? xx
longifolene 2.9 h > 33 day
linalool 52 min 55 min 0.66-0.72 x
6 methyl-5-heptene-2-one 53 min 1.0 h 0.75
high OH yield, sink of OH
high OH yield, source of OH, and τO3 ~ τTurbulent
OH yield? source of OH, but τO3 << τTurbulent
OH sources: VOC ozonolysisOH sources: VOC ozonolysis
OH-COH-C55HH88, ~ -25 in , ~ -25 in
surface layersurface layer
OO33-terpinolene-terpinolene
Terpinolene brings some more OH higher up in the PBL: However this is for an emission flux of
terpinolene of 10 x monoterpene emission flux
This resembles a reactive alkene emission flux comparable to that of
isoprene!
OH sources: VOC ozonolysisOH sources: VOC ozonolysis
jO3
OH recycling in isoprene oxidation product reactions
Simulated chemical sources and sinks of OH over land, day2, 18UT
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HCHO [ppbv]
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day 3
day3, high VdCH2O
day 3, L60Substantial overstimation
HCHO
OH sinks: other compounds besides isopreneOH sinks: other compounds besides isoprene
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CO [ppbv]
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CO
Reasonable agreement in PBL
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H2O2 [ppbv]
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H2O2
Good agreement
Simulated HCHO concentrations for L60, Femisop=0.25
Nocturnal build-up of isoprene oxidation products such as HCHO, MVK, Methac., etc.: How significant is this residual
layer chemistry for daytime chemistry and exchanges?
Precursors and oxidation products: HCHOPrecursors and oxidation products: HCHO
Conclusions and outlook Conclusions and outlook Gabriel observations have indicated that the oxidizing capacity over Gabriel observations have indicated that the oxidizing capacity over pristine tropical forest is substantially larger then previously assumedpristine tropical forest is substantially larger then previously assumed
Gabriel observations have indicated that the oxidizing capacity over Gabriel observations have indicated that the oxidizing capacity over pristine tropical forest is substantially larger then previously assumedpristine tropical forest is substantially larger then previously assumed
This (partly) explains the misrepresention of CThis (partly) explains the misrepresention of C55HH88 concentrations in concentrations in
ACTMs and is expected to have a significant impact of the lifetime of CHACTMs and is expected to have a significant impact of the lifetime of CH4 4
and pollutants (and aerosol production?)and pollutants (and aerosol production?)
This (partly) explains the misrepresention of CThis (partly) explains the misrepresention of C55HH88 concentrations in concentrations in
ACTMs and is expected to have a significant impact of the lifetime of CHACTMs and is expected to have a significant impact of the lifetime of CH4 4
and pollutants (and aerosol production?)and pollutants (and aerosol production?)
The actual mechanims that explains this much larger OH The actual mechanims that explains this much larger OH concentration is still under investigation focussing on reactions concentration is still under investigation focussing on reactions involving isoprene oxidation productsinvolving isoprene oxidation products
The actual mechanims that explains this much larger OH The actual mechanims that explains this much larger OH concentration is still under investigation focussing on reactions concentration is still under investigation focussing on reactions involving isoprene oxidation productsinvolving isoprene oxidation products
However, interpretation of the observations has also revealed an However, interpretation of the observations has also revealed an potentially important role of longer-lived compounds with chemical potentially important role of longer-lived compounds with chemical transformations occuring in the nocturnal inversion- and residual layer transformations occuring in the nocturnal inversion- and residual layer
However, interpretation of the observations has also revealed an However, interpretation of the observations has also revealed an potentially important role of longer-lived compounds with chemical potentially important role of longer-lived compounds with chemical transformations occuring in the nocturnal inversion- and residual layer transformations occuring in the nocturnal inversion- and residual layer
Future AC campaigns; nocturnal observations including Future AC campaigns; nocturnal observations including airborne/tetherered balloon observations to reach residual layerairborne/tetherered balloon observations to reach residual layer
Future AC campaigns; nocturnal observations including Future AC campaigns; nocturnal observations including airborne/tetherered balloon observations to reach residual layerairborne/tetherered balloon observations to reach residual layer
Thank you !Thank you !