Environmental Modelling, Security Measures and Decision Making Zahari Zlatev National Environmental...
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Environmental Modelling, Security Measures and Decision Making Zahari Zlatev Zahari Zlatev National Environmental Research Institute National Environmental Research Institute Frederiksborgvej 399, P. O. Box 358 Frederiksborgvej 399, P. O. Box 358 DK-4000 Roskilde, Denmark DK-4000 Roskilde, Denmark [email protected] [email protected]
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Transcript of Environmental Modelling, Security Measures and Decision Making Zahari Zlatev National Environmental...
Environmental Modelling, Security Measures and Decision Making
Zahari ZlatevZahari Zlatev
National Environmental Research InstituteNational Environmental Research Institute
Frederiksborgvej 399, P. O. Box 358Frederiksborgvej 399, P. O. Box 358
DK-4000 Roskilde, DenmarkDK-4000 Roskilde, Denmark
[email protected]@dmu.dk
CONTENTS
Two types environmental modelsTwo types environmental models Critical levels established in EUCritical levels established in EU Critical levels and decision makingCritical levels and decision making Critical levels and climatic changesCritical levels and climatic changes UNI-DEMUNI-DEM – Mathematical Description – Mathematical Description Numerical TreatmentNumerical Treatment Parallel ComputationsParallel Computations Designing a Set of ScenariosDesigning a Set of Scenarios Some ResultsSome Results Major ConclusionsMajor Conclusions
Generic Formulation of an Air Pollution Model
,...,q,s
z
cK
zz
)(wc
),c...,c(cQE
)ck(k
y
cK
yx
cK
x
y
)(vc
x
)(uc
t
c
sz
s
qss
sss
sy
sx
sss
21
transportvert.
emis.chem.,
deposition
diffusionhor.
transporthor.
21
21
Using splitting: advantages and drawbacks
Applying splitting techniques
diffusionhor.
transporthor.
)1()1(
)1()1()1(
y
cK
yx
cK
x
y
)(vc
x
)(uc
t
c
sy
sx
sss
Coupling the sub-models
emis.chem.,
deposition
)2()2(2
)2(1
)2(21
)2(
),c...,c(cQE
)ck(kt
c
qss
ssss
exchange vert.)3()3()3(
z
cK
zz
)(wc
t
c sz
ss
Numerical treatment of the horizontal transport
diffusionhor.
transporthor.
)1()1(
)1()1()1(
y
cK
yx
cK
x
y
)(vc
x
)(uc
t
c
sy
sx
sss
Need for faster but still sufficiently accurate methods
NgHgdt
dgP )1()1(
)1(
,
1. How to obtain the system of ODEs?2. How to solve the system of ODEs?Explicit methods with a stability control
Numerical treatment of the chemical reactions
Ngtgfdt
dg )2()2(
)2(
),,(
Need for faster but still sufficiently accurate methods
emis.chem.,
deposition
)2()2(2
)2(1
)2(21
)2(
),c...,c(cQE
)ck(kt
c
qss
ssss
1. No spatial derivatives2. Non-linear and stiff system of ODEs3. Extremely badly scaled4. Implicit numerical methods
Numerical treatment of the vertical exchange
NgHgdt
dgP )3()3(
)3(
,
Need for faster but still sufficiently accurate methods
exchange vert.)3()3()3(
z
cK
zz
)(wc
t
c sz
ss
1. P and H depend on the spatial discretization2. Linear and stiff system of ODEs3. Implicit numerical methods4. This sub-model is cheaper than the other two
UNI-DEM
Initializing the model:Initializing the model:
NX:NX: 96, 288, 480 96, 288, 480
NY:NY: NY = NX NY = NX (rectangular domains)(rectangular domains)
NZ:NZ: 1 or 10 1 or 10 (easy to put more layers)(easy to put more layers)
N_SPECIES:N_SPECIES: 35, 56, 168 35, 56, 168 (RADM2, RACM) (RADM2, RACM)
N_CHUNKS:N_CHUNKS: chunks for parallel runs chunks for parallel runs
N_REFINED:N_REFINED: related to emissions, 0 or 1 related to emissions, 0 or 1
N_YEAR:N_YEAR: year (any year from 1989 to 2004) year (any year from 1989 to 2004)
Size of the involved matrices
Discretization Equations Time-stepsDiscretization Equations Time-steps
96x96x10 3 225 600 35 52096x96x10 3 225 600 35 520
288x288x10 29 030 400 106 560288x288x10 29 030 400 106 560
480x480x10 80 640 000 480x480x10 80 640 000 213 120213 120
Assumption: 35 chemical species are usedAssumption: 35 chemical species are used
Why refined grids are needed?Why refined grids are needed?
Nitrogen dioxide pollution in Europe
Nitrogen emissions in Denmark
NO2 pollution in Denmark (coarse grid)
NO2 pollution in Denmark (fine grid)
Variation of the numbers of “bad days”
Conclusions Take the inter-annual variations into account: runs over Take the inter-annual variations into account: runs over long time long time
periodsperiods (20-30 years) are necessary (20-30 years) are necessary It is not enough to use scenarios based only on variations of the It is not enough to use scenarios based only on variations of the
anthropogenic emissions: the anthropogenic emissions: the natural emissionsnatural emissions are also important are also important Comparing only concentrations is Comparing only concentrations is not enoughnot enough: quantities related to : quantities related to
the concentrations and having damaging effects might vary very the concentrations and having damaging effects might vary very much even if the variations of the concentrations are smallmuch even if the variations of the concentrations are small
Large setsLarge sets of scenarios are to be used of scenarios are to be used The use of The use of fine resolutionfine resolution discretization is highly desirable discretization is highly desirable A direct consequence of the above requirements: need for A direct consequence of the above requirements: need for better better
and fasterand faster mathematical and computational tools (numerical mathematical and computational tools (numerical methods, reordering the computations, parallel codes, efficient methods, reordering the computations, parallel codes, efficient exploitation of computer grids)exploitation of computer grids)
Data assimilationData assimilation might lead to some considerable improvements might lead to some considerable improvements Statistical and graphicalStatistical and graphical representation of the results to make them representation of the results to make them
easily understandable even for non-specialistseasily understandable even for non-specialists
More details
1. Z. Zlatev and I. Dimov: ”Computational and ”Computational and Numerical Challenges in Environmental Modelling”,Numerical Challenges in Environmental Modelling”, Elsevier, Amsterdam - Boston - Heidelberg -New York - Elsevier, Amsterdam - Boston - Heidelberg -New York - Oxford - Paris - San Diego - Singapore - Sydney - Oxford - Paris - San Diego - Singapore - Sydney - Tokyo, Tokyo, 2006.2006.
2.2. Z. Zlatev et al.:Z. Zlatev et al.: “Impact of Climate Changes on “Impact of Climate Changes on Pollution Levels in Europe”, Pollution Levels in Europe”,
http://www.softasap.net/ips/climatic_scenarios_NATO.pdf
http://www2.dmu.dk/atmosphericenvironment/Climate%20and%20Pollutionhttp://www2.dmu.dk/atmosphericenvironment/Climate%20and%20Pollution
