Common conceptual framework for modelling biosphere atmosphere exchanges of gases and aerosols: needs, constraints, existing schemes.

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1 Common conceptual framework for modelling biosphere atmosphere exchanges of gases and aerosols: needs, constraints, existing schemes Raia Silvia Massad Benjamin Loubet

2 What is the problem today Our understanding of global change Climate change Anthropogenic pressure on the environment Land use land cover changes Global change impacts terrestrial ecosystems and human health The scientific community must propose tools to evaluate ways to mitigate those impacts (models and future scenarios) The models need to simulate impacts and feed backs of global change on Terrestrial ecosystem functioning Air quality GHG balance

3 Why didn t we solve it yet? 3 distinct communities 3 distinct spatial scales Global scale (climate change global vegetation change) Regional scale (air quality operational models) Local scale (ecosystem - process understanding) Different communities Different compounds NH3 NOx/O3 VOC Aerosols and acid gases GHG Momentum, heat Metallic Trace elements and POPs (Hg, Pesticide, )

4 Our needs Generic model of surface atmosphere exchange of gases and aerosols (link between different compound communities) Operating at the regional scale Accounting for bi-directional exchanges between atmosphere and ecosystems Accounting for interaction between different compounds (air chemistry, ecosystem functioning, ) Linked explicitly with environmental conditions (temperature, air humidy, precipitation, )

5 Example of existing schemes in regional CTM Decoupling of emissions and deposition Depositionbasedon «depositionvelocity» approach Emissions basedon empiricalmodelsor emission maps CMAQ exchange scheme SMOKE Same Logic applies for EMEP, CMAQ, Chimere,.!!!

6 Example of existing schemes in regional CTM CMAQ exchange scheme NH 3 (Bash et al., 2012) Includes a bi-directional exchange of NH 3 Accountsfor soilnh + 4 concentrations and fertilizer application throughthe EPIC model EPIC isrunwiththe same meteorology as CMAQ Cooter et al., 2012.

7 Example of existing schemes in regional CTM EMEP exchange scheme O 3 DO3SE (Emberson et al., 2001) Estimate the risk of O 3 damage to European vegetation Provide estimates of total O 3 deposition and O 3 risk Links photosynthesis, stomatal conductance and Ozone deposition Recently accounts for soil moisture Büker et al., 2012

8 Existing schemes The different «ideal» schemes for different compounds -Can we harmonize those schemes into one Which time scale? Which spatial resolution? Which model components are essential now and for further development?

9 Ideal Ammonia scheme A resistance approach could theoretically represent all situations An empiricalapproachcouldbea first step in animal housing, Which time scale? hourly Which spatial resolution? Minimum 2 layers (leaf and soil/litter) Which model components are essential? Linkingto ecosystem/management models Stomataland soil/litter compensation points In-canopy homogenous chemical reactions Dynamic cuticularexchange (simpler version)?? Dynamic modelling of grazing(seabird approach)? Nemitz et al. 2001

10 Ideal NO x /O 3 scheme Which time scale? hourly Which spatial resolution? Multi-layer (how many?) 3 layers Which model components are essential? Soil NO emissions Solving the energy balance In-canopy homogenous chemical reactions multi pollutant Soil and cuticular deposition Ozone impact on plant functionning(photosynthesis, stomats, ) coupling with vegetation model Basic canopy parameters (LAI, hc, ) StomatalNO2 compensation point? Leaf surface chemical reactions?? NO x <-> O 3 NO x <-> O 3 JNO 2 Temp RH Compensation Points Leaf biology Surface Thermodynamic And water

11 Which time scale? Sub-hourly? Which spatial resolution? Multi-layer (high resolution 3 to 5) Which model components are essential? Samelandcoverfor emissionsand depositions Ideal VOC scheme Simple compensation point model Foliar emissions (link to plant functionning- stomates) Soil sources and sinks In-canopy chemical reactions In-canopy turbulent transport Leaf surface chemical reactions? Sub-grid scale variability directional exchange? Which VOCs to consider and how to classify them? Premature to consider a single model - should design a model structure that could eventually integrate VOC s

12 Ideal Aerosol and acid gas scheme Which time scale? Order of minutes Which spatial resolution? Multi-layered for the moment need sensitivity study (above and within) modularity Which model components are essential? Surface co-deposition (SO 2 + HNO 3 + HCl) -> Inorganic aerosol thermodynamic model for the leaf-surface Water at the leaf surfaces its heterogeneity (evaporation?) In-canopy chemical reactions In-canopy turbulent transport Stomatal conductance Not one model!!! Turbulent transport - resistance - stability inside - interaction with chemistry Size distribution Speciation Interaction with humidity Cuticular and leaf wetness Temperature, RH, g s

13 Remaining questions and challenges Vertical resolution Time resolution Availability of environmental variables Availability of spatially explicit management variables (databases, scenarios, ) Sub-grid variability Validation data Not to forget Link to ecosystem models Link to dynamic vegetation models

14 4 Different components of the framework Leafand plant Soiland Leafsurface and physiology Litter air chemistry turbulance Working out the common framework Vision and practicality for CTM