Aerosol microphysical properties during anticyclonic flow conditions over Europe [Elektronische Ressource] / vorgelegt von Thomas Hamburger

Thomas Hamburger

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• Physik

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• Publié par: ludwig-maximilians-universitat_munchen
• Publié le: 01 janvier 2010
• Nombre de lectures: 23
• Poids de l'ouvrage: 7 Mo

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Aerosol microphysical properties
during anticyclonic flow conditions
over Europe
Thomas Hamburger
München 2010Aerosol microphysical properties
during anticyclonic flow conditions
over Europe
Thomas Hamburger
Dissertation
an der Fakultät für Physik
der Ludwig–Maximilians–Universität
München
vorgelegt von
Thomas Hamburger
aus München
München, den 22. Dezember 2010Erstgutachter: PD Dr. Andreas Petzold
Zweitgutachter: Prof. Dr. Bernhard Mayer
Tag der mündlichen Prüfung: 23. Februar 2011Contents
Contents i
1 Introduction 1
2 Basics of aerosol microphysical properties 7
2.1 Aerosolsources,transformationsandsinks................ 7
2.2 Aerosolsizedistribution................ 11
2.3 Aerosolopticalproperties .... 14
2.3.1 Scateringandabsorptionoflightbyaerosolparticles...... 14
2.3.2 Changes of optical properties due to changes in aerosol composition 19
2.3.3 Changes of optical properties due to changes in relative humidity 21
3 Methods and implementation of aerosol airborne measurements 25
3.1 Methodsofaerosolairbornemeasurementsanddataanalysis...... 25
3.1.1 Aerosolnumberconcentrations .................. 25
3.1.2 Aerosolsizedistributions............ 26
3.1.3 Aerosolmixingstate... 28
3.1.4 Scateringandabsorptionoflightbyaerosolparticles...... 30
3.1.5 Procesingthedataofaerosolairbornemeasurements 32
3.2 Developmentofanewmethodtoanalyseairmastrajectories..... 36
3.2.1 Airmastrajectories........................ 36
3.2.2 ThetrajectorycalculationandanalysistoolFLYTUL...... 37
3.2.3 The EDGAR 3.2 Fast Track 2000 dataset . . . 39
3.2.4 Boundary layer indices . ........... 41
3.2.5 Classification of air mass trajectories using time weighted averaging 42
3.3 TheEUCAARI-LONGREXcampaign ........ 46
3.3.1 Objectives and strategy of the EUCAARI-LONGREX campaign 47
3.3.2 Theaircraftandinstrumentationalsetup............. 48
3.3.3 ImplementationoftheEUCAARI-LONGREXcampaign.... 50
iii CONTENTS
4 Results and discussion of aerosol measurements obtained during the
EUCAARI-LONGREX campaign in May 2008 55
4.1 ThemeteorologicalsituationinMay2008................. 55
4.1.1 TheevolutionofthemeteorologicalsituationoverEurope.... 5
4.1.2 Theanticyclonicblockingevent.................. 58
4.1.3 Thesynopticsituationwithinaclimatologicalcontext...... 59
4.1.4 The transport pathways of anthropogenic pollution within the
anticyclonicwindfield............ 61
4.2 The impact of anthropogenic pollution on aerosol microphysical proper-
tiesinremoteregions:AcasestudysouthwestofIreland........ 64
4.2.1 Aerosol optical depth retrieved from satellite imagery and LI-
DARprofiles ............................ 64
4.2.2 Vertical profiles of in-situ measured aerosol microphysical prop-
erties...................... 67
4.2.3 Aerosol size distributions and deduced optical properties within
theobservedpolutionlayers.................... 70
4.2.4 Transportanalysisofpollutedairmasses...... 76
4.2.5 Comparison of airborne measurements with previous studies at
MaceHead,Ireland.............. 7
4.3 Temporal evolution of the pollution situation over Europe in May 2008:
Analysisofgroundbasedmeasurements.................. 80
4.3.1 Groundbasedmeasurements:Timeseriesdata... 80
4.3.2 Groundbasedmeasurements:Discusion............. 87
4.3.3 Anthropogenic origin of increased accumulation mode number
concentrationsmeasuredatthegroundstations......... 89
4.3.4 Ground based measurements compared with airborne measure-
ments ................................ 90
4.4 TheverticalaerosoldistributionoverEuropeinMay208 93
4.4.1 The temporal evolution of the vertical number concentration over
SouthGermany................ 93
4.4.2 Regionalverticalprofilesduringanticyclonicconditions..... 97
4.5 ThehorizontalaerosoldistributionoverEuropeinMay208......104
4.5.1 Verticalclasificationofthetroposphere .............104
4.5.2 Horizontal distribution of aerosol microphysical properties during
anticyclonicconditions.......................105
4.5.3 SizedistributionsmeasuredoverEurope......109
4.5.4 Chemical composition of aerosol particles measured aboard the
BAe-146....................13CONTENTS iii
5 Application of a new trajectory analysis method 115
5.1 Comparisonofmodeldatawithin-situmeasurements..........16
5.2 Sourcestrengthandcloudcover............119
5.3 Airmasclasificationusingtemporalweightedaverages........126
5.3.1 Clasificationofairmasesintodefinedageclases126
5.3.2 Airmasclasificationforgroundbasedmeasurements .....127
5.3.3 Air mass classification using different sigma factorssf130
5.3.4 Airmassclassificationforairbornemeasurements........132
5.4 The applicability of FLYTUL . . .....................134
6 Summary & conclusion 137
Bibliography 141
A Tables 159
B Figures 167
List of symbols 175
List of abbreviations 179
Acknowledgements 181
Curriculum Vitae 183iv CONTENTS
Abstract
Aerosols play an important role in atmospheric physics. The airborne particles
in diameters of a few nanometres to some micrometres affect the climate system
by altering the energy balance of the atmosphere. However, the quantification
of the climate effect is an open question until today. Large uncertainties exist in
the knowledge of the global aerosol distribution and their properties.
The present work assesses the spatial and temporal distribution and variability
of aerosol particles and their properties above Europe during stable synoptic con-
ditions. A data set of airborne measurements unique in its spatial dimensions
over Europe was obtained within this work in May 2008. It covers microphysical
aerosol properties throughout the whole tropospheric column above Central and
Western Europe. The airborne aerosol measurements were performed aboard the
DLR Falcon 20 within the EUCAARI-LONGREX field campaign. The aircraft
operated from Oberpfaffenhofen, Germany.
The influence of source contributions on the aerosol particles and ageing pro-
cesses over a densely populated region were measured and analysed using a new
developed trajectory analysis tool (FLYTUL). The trajectory analysis tool uses
the EDGAR 3.2 Fast Track 2000 dataset to quantify the source contributions
along each trajectory of a trajectory bundle for a qualitative classification of the
air mass. Meteorological information along the air mass transport pathway is
retrieved from the ECMWF.
The prevailing anticyclonic conditions led to an increase of particulate matter
in the continental boundary layer. Total aerosol number concentrations reached
−3 −322000 cm , number concentrations of accumulation mode particles 1600 cm .
The volume fraction of secondary aerosol matter increased to 95 % for submicron
particles due to coagulation processes and condensation of the abundant aerosol
precursor gases within the dry and stable meteorological conditions.
A positive gradient of particulate matter was observed along the anticyclonic
transport pathway from the Baltic Sea towards the Benelux States and Southern
England. The vertical aerosol distribution featured clean conditions with respect
to particles in the lower free troposphere and suggested a trapping of aerosol par-
ticles inside the boundary layer.
Undisturbed transport of continental anthropogenic pollutants to remote regions
was observed and a direct effect on the radiative properties of the aerosol popu-
lation was found. 90 % of the aerosol optical depth above the Atlantic southwest
of Ireland was caused by the pollution layers, which originated from continental
Europe.
The analysis of air mass transport and ageing processes indicated that the main
coagulation process of aerosol particles happens within the first 12–24 h. The
saturation of the coagulation process occurred after two days.CONTENTS v
Kurzfassung
Aerosole spielen eine wichtige Rolle im Bereich der Atmosphärenphysik. Par-
tikel mit Durchmessern von wenigen Nanometern bis einigen Mikrometern bee-
influssen das Klima indem sie die Energiebilanz der Atmosphäre ändern. Die
Quantifizierung dieses Effektes ist jedoch bis heute ein ungelöstes Problem. Das
Wissen um die globale Aerosolverteilung und deren Eigenschaften ist mit großen
Unsicherheiten behaftet.
Die vorliegende Arbeit bestimmt die räumliche und zeitliche Verteilung und Vari-
abilität von Aerosolpartikeln und deren Eigenschaften während stabilen synop-
tischen Bedingungen über Europa. Während dieser Arbeit wurde ein in seiner
räumlichen Ausdehnung über Europa einmaliger Datensatz von flugzeuggetra-
genen Messungen gewonnen. Mikrophysikalische Aerosoleigenschaften wurden
über den gesamten Höhenbereich der Troposphäre über Mittel- und Westeuropa
gemessen. Die Messungen wurden auf dem Forschungsflugzeug DLR Falcon 20
während der EUCAARI-LONGREX Messkampagne im Mai 2008 durchgeführt.
Die Flüge starteten von Oberpfaffenhofen, Deutschland aus.
Der Einfluss verschiedener Quellbeiträge über dicht bevölkerten Gebieten und
von Alterungsprozessen auf Aerosolpartikel wurde gemessen und mit Hilfe eines
neu entwickelten Trajektorienanalyseprogramms ausgewertet (FLYTUL). Das
Trajektorienanalyseprogramm verwendet die EDGAR 3.2 Fast Track 2000 Daten-
bank um Quellbeiträge entlang jeder ei