Fighting the Great Challenges in Large-scale Environmental Modelling

I. Dimov

Great challengesGreat challenges in environmental in environmental modellingmodelling

Impact of Impact of climatic changesclimatic changes on pollution on pollution levelslevels

Scenarios Scenarios for climatic changes for climatic changes Impact Impact of climate changes on of climate changes on EuropeanEuropean

pollution levelspollution levels ConclusionsConclusions

Scientific Cooperation

ACET, Reading (V. Alexandrov, I. Dimov);ACET, Reading (V. Alexandrov, I. Dimov); Bulgarian Academy of Sciences – IPP, Sofia (Tz. Bulgarian Academy of Sciences – IPP, Sofia (Tz.

Ostromsky, K. Georgiev, E. Atanassov);Ostromsky, K. Georgiev, E. Atanassov); National Environmental Research Institute, National Environmental Research Institute,

Roskilde, Denmark (Z. Zlatev, G. Geernaert, Roskilde, Denmark (Z. Zlatev, G. Geernaert, Jorgen Brandt).Jorgen Brandt).

Great challenges for the modellersGreat challenges for the modellers

Some of the major challenges

High resolutionHigh resolution computations: lead to huge computations: lead to huge computational taskscomputational tasks

Taking into account Taking into account all relevantall relevant factors: factors: leads to long series of runs with different leads to long series of runs with different scenariosscenarios

Impact of Impact of climatic changesclimatic changes on high on high pollution levels: leads to long-term runs pollution levels: leads to long-term runs (again with many scenarios) (again with many scenarios)

Climate changes in Europe There are many uncertainties related to the climate

changes in the future (Houghton et al., 2001). It is nevertheless worthwhile to investigate the impact

of possible climatic changes on the pollution levels. Three climatic scenarios have been introduced and

used to study the impact of the predicted climatic changes in Europe on ozone pollution levels in Europe.

Houghton et al. 2001, Climate Changes 2001: The

Scientific Basis, Cambridge University Press, Cambridge-

New York-Melbourne-Madrid-Cape Town, 2001

Climate scenario 1 The The SRES A2SRES A2 Scenario in Scenario in Houghton et al. 2001Houghton et al. 2001 limited to limited to

the space domain of our model is used in this studythe space domain of our model is used in this study The annual mean value of the temperature is assumed to be The annual mean value of the temperature is assumed to be

increased in the intervals prescribed by increased in the intervals prescribed by SRES A2SRES A2

Miba ii ...,,2,1],,[

The temperature at cell is increased by an amount of at time where is randomly generated in the interval The mathematical expectation of the increase of the annual mean of the temperature in cell is

i)( nii tca nt )( ni tc

],0[ ii ab

2/)( ii ab iOnly temperatures were changed in this scenario

THE SRES - A2 SCENARIO

Climatic Scenario 2Recommendations in Houghton et al. 2001Recommendations in Houghton et al. 2001 There will be There will be higher maximumhigher maximum temperatures and temperatures and more hot more hot

daysdays in land areas in land areas (changes in summer over land)(changes in summer over land) There will be higher minimum temperatures, fewer cold There will be higher minimum temperatures, fewer cold

days and fewer frost days in nearly all land areasdays and fewer frost days in nearly all land areas The diurnal temperature range will be reduced over land The diurnal temperature range will be reduced over land

areasareas The changes that are needed to satisfy the above requirementsThe changes that are needed to satisfy the above requirements

were made so that the annual means were as in the previouswere made so that the annual means were as in the previous

scenario scenario (a requirement for consistency with SRES A2)(a requirement for consistency with SRES A2)

Cloud covers in summer over land were reduced (only theCloud covers in summer over land were reduced (only the

temperatures were changed in Climatic Scenario 1)temperatures were changed in Climatic Scenario 1)

Climatic Scenario 3Recommendations about the amount of precipitationRecommendations about the amount of precipitation There will be more precipitation eventsThere will be more precipitation events There will be increased summer drying and associated risk of droughtThere will be increased summer drying and associated risk of drought

1. The precipitation events during winter were increased (both over land 1. The precipitation events during winter were increased (both over land and over water)and over water)

2. The precipitation events in the continental part of Europe were reduced 2. The precipitation events in the continental part of Europe were reduced during summerduring summer

Similar changes were made for the Similar changes were made for the humidityhumidity

The cloud cover during The cloud cover during winterwinter were were decreased decreased, while the same cloud, while the same cloud

covers as in Climatic Scenario 2 were used during summercovers as in Climatic Scenario 2 were used during summer

The changes were superimposed over the changes in the previous The changes were superimposed over the changes in the previous scenarioscenario

Air pollution scenarios Basic ScenarioBasic Scenario (using meteorology and emissions for 1989-1998) (using meteorology and emissions for 1989-1998) Constant emissionsConstant emissions (using meteorology for 1989-1998, but keeping (using meteorology for 1989-1998, but keeping

the 1989 emissions during the whole period)the 1989 emissions during the whole period) Constant meteorologyConstant meteorology (using meteorology for 1989 during the whole (using meteorology for 1989 during the whole

period and emissions for 1989-1998)period and emissions for 1989-1998) Climatic Scenario 1Climatic Scenario 1 (using 10 hypothetical years with the temperatures (using 10 hypothetical years with the temperatures

from Climatic Scenario 1 and the other parameters as in the Basic from Climatic Scenario 1 and the other parameters as in the Basic Scenario)Scenario)

Climatic Scenario 2Climatic Scenario 2 (using 10 hypothetical years with the temperatures (using 10 hypothetical years with the temperatures from Climatic Scenario 2 and the other parameters as in the Basic from Climatic Scenario 2 and the other parameters as in the Basic Scenario) Scenario)

Climatic Scenario 3Climatic Scenario 3 (using 10 hypothetical years with the temperatures (using 10 hypothetical years with the temperatures from Climatic Scenario 3 and the other parameters as in the Basic from Climatic Scenario 3 and the other parameters as in the Basic Scenario)Scenario)

Validation of the model results Need Need for validationfor validation Comparison of Comparison of model resultsmodel results obtained by using the Basic Scenario obtained by using the Basic Scenario

(1989-1998) with corresponding (1989-1998) with corresponding measurementsmeasurements Major observation:Major observation: both the model results and the measurements show both the model results and the measurements show

a trend of decreasing, which is to be expected, because the European a trend of decreasing, which is to be expected, because the European emissions were decreased in the period 1989-1998emissions were decreased in the period 1989-1998

Another observation:Another observation: the comparison between measurements and the comparison between measurements and model results becomes as a rule better at the end of the studied periodmodel results becomes as a rule better at the end of the studied period

Difficulties:Difficulties: the model calculates a representative value for the grid- the model calculates a representative value for the grid-cell, while the measurements are taken at a given point.cell, while the measurements are taken at a given point.

The results seem to be The results seem to be satisfactory satisfactory for the different concentrations. Forfor the different concentrations. For quantities related to high ozone concentrationsquantities related to high ozone concentrations the situation is more the situation is more complicated.complicated. These quantities are very These quantities are very sensitive to errorssensitive to errors. . Missing Missing measurementsmeasurements are another big problem are another big problem

DANISH MEASUREMENT STATIONS

Model results vs measurements

Impact of small errors on the accuracy of some of the results

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Constant emissions vs constant meteorology Running with the same emissions:Running with the same emissions: the trend of decreasing the trend of decreasing

of the pollution levels disappears, but the pollution levels of the pollution levels disappears, but the pollution levels still vary considerably from one year to anotherstill vary considerably from one year to another

Running with the same meteorology:Running with the same meteorology: the trend of the trend of decreasing can still be seen, but the curves are much decreasing can still be seen, but the curves are much smoother (the pollution levels do not vary too much from smoother (the pollution levels do not vary too much from one year to another)one year to another)

Main conclusion:Main conclusion: runs on long intervals are to be carried runs on long intervals are to be carried out in order to obtain full information about the variation of out in order to obtain full information about the variation of the pollution levels (both the variations that are due to the the pollution levels (both the variations that are due to the changed meteorological conditions and the variations that changed meteorological conditions and the variations that are due tp the changed emissions).are due tp the changed emissions).

Emissions vs meteorology

Emissions vs meteorology

The Climatic Scenarios vs the Basic Scenario For most of the pollutants the changes in Europe are very For most of the pollutants the changes in Europe are very

smallsmall The annual means of the ozone concentrations in Denmark The annual means of the ozone concentrations in Denmark

are larger when the Basic Scenario is usedare larger when the Basic Scenario is used The quantities related to high ozone concentrations are The quantities related to high ozone concentrations are

increased when the Climatic Scenario 3 is run. The increased when the Climatic Scenario 3 is run. The increases are small in Denmark, but considerable increases increases are small in Denmark, but considerable increases can be seen in some parts of Europe (especially, in the can be seen in some parts of Europe (especially, in the highly polluted areas of Western and Central Europe)highly polluted areas of Western and Central Europe)

Climatic Scenario 3

Climatic Scenario 3

Climatic Scenario 3

Climatic Scenario 3

Climatic Scenario 3

Conclusions The results The results indicateindicate that the influence of the that the influence of the

expected future climate changes on the expected future climate changes on the concentration levels in Europe is concentration levels in Europe is not very not very largelarge

Unfortunately, this conclusion Unfortunately, this conclusion cannot be cannot be extendedextended for the critical limits established for the critical limits established in the in the EU Ozone Directive from 2002EU Ozone Directive from 2002. The . The changes in the quantities related to the changes in the quantities related to the critical levels critical levels can be rather considerablecan be rather considerable..