Download Common conceptual framework for modelling biosphere

Common conceptual framework for
modelling biosphere atmosphere
exchanges of gases and aerosols:
needs, constraints, existing schemes
Raia Silvia Massad
Benjamin Loubet
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
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,
…)
…
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, …)
Example of existing schemes in regional CTM
CMAQ exchange scheme
• Decoupling of emissions
and deposition
• Deposition based on
« deposition velocity »
approach
• Emissions based on
empirical models or
emission maps
SMOKE
Same Logic applies for EMEP, CMAQ, Chimere, ….!!!
Example of existing schemes in regional CTM
CMAQ exchange scheme – NH3
(Bash et al., 2012)
• Includes a bi-directional
exchange of NH3
• Accounts for soil NH4+
concentrations and fertilizer
application through the
EPIC model
• EPIC is run with the same
meteorology as CMAQ
Cooter et al., 2012.
Example of existing schemes in regional CTM
EMEP exchange scheme – O3 – DO3SE
(Emberson et al., 2001)
• Estimate the risk of O3 damage
to European vegetation
• Provide estimates of total O3
deposition and O3 risk
• Links photosynthesis, stomatal
conductance and Ozone
deposition
• Recently accounts for soil
moisture
Büker et al., 2012
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 ?
Ideal Ammonia scheme
– A resistance approach could
theoretically represent all situations
– An empirical approach could be a
first step in animal housing, …
– Which time scale?
• hourly
– Which spatial resolution?
• Minimum 2 layers (leaf and soil/litter)
– Which model components are
essential?
• Linking to ecosystem/management
models
• Stomatal and soil/litter compensation
points
• In-canopy homogenous chemical
reactions
• Dynamic cuticular exchange (simpler
version)??
• Dynamic modelling of grazing (seabird approach)?
Nemitz et al. 2001
Ideal NOx/O3 scheme
– Which time scale?
• hourly
– Which spatial resolution?
JNO2
Temp
RH
Compensation
Points
Leaf biology
• 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,…)
• Stomatal NO2 compensation
point?
• Leaf surface chemical reactions??
NOx <-> O3
NOx <-> O3
Surface
Thermodynamic
And water
Ideal VOC scheme
– Which time scale?
• Sub-hourly?
– Which spatial resolution?
• Multi-layer (high resolution 3 to 5)
– Which model components are
essential?
• Same landcover for emissions and
depositions
• 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
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)
Turbulent transport
- resistance
- stability inside
- interaction with chemistry
modularity
– Which model components
are
essential?
• Surface co-deposition (SO2 + HNO3
+ 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!!!
Size distribution
Speciation
Interaction with humidity
Cuticular and leaf wetness
Temperature, RH, gs
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
4 Different components of the framework
Leaf and plant
physiology
Soil and
Litter
Leaf surface and
air chemistry
Working out the common framework
Vision and practicality for CTM
turbulance