2003-10-08 1 Modelling of Acid deposition in South Asia Magnuz Engardt Swedish Meteorological and...
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Transcript of 2003-10-08 1 Modelling of Acid deposition in South Asia Magnuz Engardt Swedish Meteorological and...
2003-10-08 1
Modelling of Acid deposition in South AsiaModelling of Acid deposition in South AsiaMagnuz Engardt Magnuz Engardt Swedish Meteorological and Hydrological Institute (SMHI)Swedish Meteorological and Hydrological Institute (SMHI)
• Introduction to Acid deposition modelling
• Description of the adopted acid deposition modelling tool - MATCH
• Presentation of sample results (comparisons with measurements and animations)
• Conclusions
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Measurements and ModellingMeasurements and Modelling
• Models and measurements both have uncertainties
• Models and measurements should be used together to explore their full potential and to increase the quality of each other
• Some features are particular to either method
• Models and measurements are both needed
Measure or calculate concentrations and depositions ?
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Why modelling?Why modelling?
• Mapping of remote regions (incl. areas without measurements)
• Source-Receptor calculations
• Scenarios (future / history / siting of emitters, receptors)
• Understand processes in the atmosphere
• Check emission inventories
• Verify measurements
• …
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In our field we have, for example,
• Numerical weather forecast models
• Climate change models
• Dispersion models including emissions, transport, depo-sition, chemical conversion etc.
• Emission inventories
• Integrated Assessment Models
• ...
What is a modelWhat is a model ??Mathematical relations based on empirical or physical lawsMathematical relations based on empirical or physical laws
Models are used everywhere in society
• Economical models
• Population models
• Technological models
• …
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Terminology (dispersion modelling)Terminology (dispersion modelling)
• “Eulerian model” The atmosphere is divided into a large number of boxes. Fluxes between boxes and processes inside boxes are taken into account.
• “Off-line model” Meteorological data from an auxiliary driver. Data can be from archived meteorology or weather forecasts, or climate scenarios.
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MATCHMATCHMultiple-scale Atmospheric Transport and Chemical modelMultiple-scale Atmospheric Transport and Chemical model
• A Eulerian off-line model
• Suitable for regional scale applications
• Present study:-Grid resolution 1°× 1° (100km × 100km )-43 layers up to ca. 26 km (lowest model layer ~20m
thick,increasing to ~800m)
-Meteorology from ECMWF (12 months of data, every 6 h)
-Emissions from EDGAR (standard, global emissioninventory)
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Quality of model outputQuality of model outputnever better than the input to the modelnever better than the input to the model
VariousParameters
Meteorology
EmissionInventory
SurfaceDeposition
AtmosphericConcentration
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Processes included in the modelProcesses included in the model
CHANGE
CONC.= EMIS + ADVXY + ADVZ + CONVZ + TURBZ + CHEM + DRYDEP + WETDEP
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Minimum set of input meteorological and Minimum set of input meteorological and ““physiographicalphysiographical” information needed to run ” information needed to run MATCH.MATCH.
• Topography (mountains etc.)
• Surface classification (land/sea, forest, desert, rise paddies, …, etc.)
• Surface state (snow/ice etc.)
• Surface roughness
• Surface albedo (=reflectivity)
• Surface pressure
• Surface temperature
• 2 m temperature
• 2 m dew point temperature (moisture content)
• 10 m wind
• Total cloud cover
• Total surface precipitation
• Mean layer temperature*
• Mean layer wind*
* Must be provided for whole atmosphere (Three-dimensional fields: all model layers). Other data is “two-dimensional”.
All meteorological data are updated every 6 hours during the 12-month period January-December 2000.
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15 August, 2000 00Z15 February, 2000 00Z
Illustration of model domain and type of Illustration of model domain and type of meteorology availablemeteorology available
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NO NO2 HNO3NO3-
NH4NO3
NH3 SO42- SO2
H0.5(NH4)1.5SO4
QNOXQNH3
QSOX
JNO2•NO2
k11•O3•NO
k12•O3•NO2
k21•OH•NO2
Kp=HNO3•NH3kA•HNO3
kB•NO3- kT•fCC SO2
D D,W D,W D,W D,W D,W D,W D,W
kgas•OH • SO2
Kp=f(RH, T) irreversible
NQNOXSQSOX
(1-N)QNOX(1-S)QSOX
min( , SO42-)
1.5NH3
reversible
ChemistryChemistryin the current model studyin the current model study
Species may be converted from the form they are originally emitted as
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Emissions from EDGAR databaseEmissions from EDGAR database(Inventory valid for 1995; includes all anthropogenic sources)(Inventory valid for 1995; includes all anthropogenic sources)
Reduced nitrogen Oxidised nitrogen Total sulphur
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DepositionDepositionin the current model studyin the current model study
• Wet depositionDeposition of tracer when precipitation occur.Species dependent “scavenging coefficient”, k, that varies with height
• Dry depositionParticles settle through gravity and gases affix to various surfaces.Deposition is a function of a ”dry deposition velocity”, vd, that varies with surface type
Deposition = tracers leaving the atmosphere and end up at the surface of the earth
airinionconcentratsurfacenearvDRYDEP d
airinionconcentrationprecipitatWETDEP k
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Model performance / requirementsModel performance / requirements
• The MATCH-model has been set-up on a number of computer platforms, including ordinary PCs (LINUX).
• Simulation times depends on computer and varies from a few hours (multi-CPU supercomputer) to several days (PCs).
• Input data occupies several Gigabyte of disk.
• MATCH is typically operated as flexible research tool, which requires plenty of experience, and computer knowledge, to use.
• MATCH can also be “packed” into a user friendly interface where the user can change and modify only a few pre-defined options.
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Sample resultsSample resultsAnnual-mean concentration in precipitation (several Indian sites)Annual-mean concentration in precipitation (several Indian sites)
Measurements
Mod
el
Sulphate(Eq l-1)
Ammonium(Eq l-1)
Nitrate(Eq l-1)
Precipitation(mm year-1)
4000 120
50100
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Sample resultsSample resultsTime-series of atmospheric Time-series of atmospheric concentrations (2 Indian sites)concentrations (2 Indian sites)
• Model
• Model
Measurements
Bhubaneswar
SO2
NO2
NH3
12
207
25
2520
Pune
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ConclusionsConclusions
• Modelling can e.g. be used to locate the origin of the deposited pollutants and to investigate future depositions based on assumed changes in emissions.
• Measurements are needed to check the quality of the model (and vice versa).
• Modelled and measured data compare fairly well - The results are reasonably robust, but can of coursealways be improved. The largest uncertainity is alwaysthe emissions inventory
• MATCH is detailed and complex thus slow.
• At present the MATCH-model runs as a research tool in Sweden
- can of course be run at an South Asian institute
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