Assessing HTAP effects on Ecosystems: Ozone and Aerosols · Assessing HTAP effects on Ecosystems:...
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[email protected] Assessing HTAP effects on Ecosystems: Ozone and Aerosols Lisa Emberson Stockholm Environment Institute, Environment Department University of York, UK HTAP, Pasadena, California Feb 1-4 th 2012
Transcript of Assessing HTAP effects on Ecosystems: Ozone and Aerosols · Assessing HTAP effects on Ecosystems:...
Assessing HTAP effects on Ecosystems: Ozone and Aerosols
Lisa EmbersonStockholm Environment Institute,
Environment DepartmentUniversity of York, UK
HTAP, Pasadena, CaliforniaFeb 1-4th 2012
Understand HTAP
ScienceImpacts Policy
Design of HTAP modelling experiments
Do we need to rethink a little the way we design these experiments……to ensure they are policy relevant….?????
The HTAP Process ???
Understand HTAP
Science
Impacts
Policy
Design of HTAP modelling
experimentsPolicyImpacts
Understand HTAP
ScienceImpacts Policy
Design of HTAP modelling experiments
Do we need to rethink a little the way we design these experiments……to ensure they are policy relevant….?????
The HTAP Process ???
Understand HTAP
Science
Impacts
PolicyDesign of HTAP
modelling experiments
Tweak models
PolicyImpacts
Mod
el o
utpu
te.g. ozone & ecosystem effects….
Conclusions from 2010 Assessment
Showed fairly substantial effect of HTAP on crop yields…causingbetween 5 to 35 % of the O3 induced crop yield loss.
BUT…. By necessity, assessment used Concentration based indices....
....for 2015 we have the possibility to perform stomatal ozone flux based ecosystem assessments in line with adopted LRTAP methods
What do we mean by flux/dry deposition?
Stomatal flux/uptake/deposition
Non-stomatal flux/uptake/deposition
External plantsurfaces
Soil
Species, cultivar,Phenology,Environmental variables (e.g. irradiance, temperature, VPD, Soil water status, CO2concentration)
What do we mean by flux/dry deposition?
Stomatal flux/uptake/deposition
Non-stomatal flux/uptake/deposition
External plantsurfaces
Soil
Species, cultivar,Phenology,Environmental variables (e.g. irradiance, temperature, VPD, Soil water status, CO2concentration)
Why is it important to use stomatal ozone flux rather than concentration (W126, AOT40, M7 etc…) based metrics?
AOT402000
FLUX2000
AOT402020
FLUX2020
Simpson et al. (2007)
Flux is not so sensitive to changes in peak O3
concentrations
Assuming gmax and rb = 50 s/m
AFst 6 in relation to O3 concentration
0
5
10
15
20
25
0 10 20 30 40 50 60
O3 (ppb)
Fst (
nmol
O3 m
-2 P
LA s
-1)
AOT40
Wheat (450)
Potato (750)
AOT40 – only able to incorporate effect of rising global background concentration above 40ppb
Why flux is less sensitive to O3 peaks And better for HTAP damage estimates ???
AFstY – able to differentiate species sensitivity to rising background concentration
16 22
Detoxification threshold
Does stomatal ozone flux provide better estimates of O3damage? ….Collation of evidence for effects important
AOT40 O3 flux
Mills et al., 2010
What tools exist to estimate flux and response ?
DO3SE: Ozone dry deposition and stomatal O3flux model
FO3 = Vg * [O3]
Göteborg University17 November 2011
Stomatal Ozone Flux
Human health EcosystemsFlux-R
relationships
Derived from experimental fumigation studies using the DO3SE stomatal algorithm
O3 dry deposition is an important component of making accurate O3mass balance calculations ...
….with implications for human health.
Vieno et al. (2010)
Is this dry deposition term also important for accurate estimates of the O3 budget ?
How can the flux based method be applied ?
The good news is that most dry deposition modules, embedded within Ozone Chemical Transport Models (CTMs), include an estimate of
stomatal ozone flux
Variation in the length of crop growing seasons in the UKPerhaps need to consider the early and late crops that might be more
susceptible to HTAP
Watson, (1947)Forests and grasslands
Extending to higher elevations
Which means that land cover (and associated dry deposition parameterisation) is very important to determine O3 deposition as air parcels
travel over large distances
Ocean deposition
How can the flux based method be applied ?
The bad news is that these CTMs embedded dry deposition schemes use different methods....
....and only one of these scheme, the DO3SE model, relates stomatal deposition directly to ecosystem effects....
What are the main differences in O3 dry deposition schemes?
Wesely (1989) Pleim et al (2001) DO3SE (2003)
Surface resistance terms
Stomatal, plant cuticle, in canopy (buoyancy, density, upper & lower canopies) ground surface
Stomatal, plant cuticle, in canopy, (empirical), ground surface, LAI
Stomatal, plant cuticle, in canopy, (empirical), ground surface, LAI
Stomatal resistance
Solar radiation, surface air temperature
Species type, growing season, photosyntheticallyactive radiation, surface air temperature, vapour pressure deficit, soil moisture content
Species type, growing season, photosynthetically active radiation, surface air temperature, vapour pressure deficit, soil moisture content
Landcoverparameterisation
North America (?)7 vegetation types and 5 seasonal categories (e.g.Agricultural land -Midsummer with lush vegetation)
North America25 vegetation types
European (& some Asian)10 deposition cover types plus >15 O3 sensitive target species for effects estimates (with climate region parameterisations)
What can be done within HTAP ?-to improve estimates of O3 dry deposition and estimate
stomatal O3 flux for ecosystem effects
1.Literature review of O3 dry deposition methods identify those most commonly used within global scale CTMs
2.Identification of the key differences in these dry deposition schemes
3.Identification of the key differences in the parameterization (for different land cover types)
4.Off-line assessment of the implications of differences in O3 dry deposition schemes…comparison with observations from site-specific flux data
What can be done within HTAP ?-to improve estimates of O3 dry deposition and estimate
stomatal O3 flux for ecosystem effects
1.On-line assessment of the effect O3 dry deposition schemes on hemispheric transport of O3; regional O3 concentrations and regional O3 induced ecosystem damage.
Global modeling could show spatial fields of i. stomtal O3 flux; ii. total O3 deposition;iii.Effect on atmospheric O3 concentration
2.HTAP modeling experiments i. investigate S-R relationship for stomatal O3 flux; ii. alter key climate relevant characteristics (i.e. simulate an extended drought
period, elevated CO2 effects on stomatal conductance, changes in surface ToC and RH% etc…) on resulting stomatal O3 flux to indicate how ecosystem risk might change under future climates.
iii.Investigate the role of landcover on O3 deposition and stomatal O3 flux
Sitch et al. 2008
O3 can indirectly affect climate change through reductions in GPP leading to alterations C sequestration...leading to more CO2 in the atmosphere
What can be done within HTAP ?-what ecosystem effects do we want to consider?
Crops, Forests, Grasslands, Biodiversity and C sequestration…..
…..but at the same time N deposition to the oceans and terrestrial biosphere can increase biological production drawing down CO2
Understand HTAP
Science
Impacts
Policy
Design of HTAP modelling experiments
Model tweaksPolicy
Mod
el o
utpu
t
Common understandingof key issues
Terry’s workshops
Needs to be done in time to inform the experimental design
• Effect of HTAP on N deposition in more pristine Northerly latitude ecosystems where as little 5 kgN/ha/year may cause damage
• Effect of N & S on acidification…time development of damage to understand rates of change of acidity and role of HTAP
• Effect of aerosols on radiation (total and diffuse fraction)….effect on photosynthesis and hence ecosystems
• Effect of pollutants (N, O3, aerosol) on NPP and C sequestration….feedbacks to climate
Impa
cts
Holloway et al. 2011
…and finally a word of warning….how to communicate to the public….
