Engine emissions and plume processes
Novel Rates of OH induced Sulfur Oxidation Implications to the Plume Chemistry of
G LEITSMANN , G ệTZ (1); S OMNITZ , H OLGER (1); Z ELLNER , R EINHARD (1)
(1) Institut fỹr Physikalische Chemie, Universitọt Duisburg Essen,Campus Essen, Essen, Germany contact: reinhard.zellner@uni-essen.de
Aircraft emissions have significant environmental impacts, particularly through contrail and cirrus cloud formation, which are influenced by sulfuric acid generated from the fuel sulfur content (FSC) The rapid oxidation of S(IV) in both the engine and plume plays a crucial role in this process However, the existing chemical kinetic data needed to accurately evaluate this oxidation remains unreliable.
Recent ab initio quantum chemical and RRKM dynamical calculations have derived novel rate coefficients for the crucial sulfur oxidation reaction OH + SO2 → HSO3, across a wide range of pressure and temperature These findings indicate that the oxidation rate of S(IV) to S(VI) in typical jet aircraft plume conditions is significantly slower than previously thought, based on earlier experimental data interpolations (Tremmel and Schumann, 1999) This discrepancy is primarily attributed to the fall-off behavior of the rate coefficient and a slight adjustment of the equilibrium constant.
We have integrated kinetic results into the BOAT code, a chemical-dynamical model for the jet regime of a B-747 airliner, predicting sulfur conversion efficiencies below 1% This efficiency is influenced by the OH emission factor and the development of the OH field in the early plume Additionally, the emission factors of NOx and organics also affect the sulfur conversion efficiency, which has been thoroughly tested.
Our research indicates that the established conversion ratio of S(IV) to S(VI), typically around 1-2% as validated by various airborne experiments, can only be replicated with adequate production of SO3 or H2SO4 within the engine or turbine Additionally, the plume effect on this conversion ratio is relatively minor.
Determination of Soot Mass Fraction, Soot Density and Soot Fractal Character in
W AHL , C LAUS (1); K APERNAUM , M ANFRED (1); K RĩGER , V ERONIQUE ; R AINER , P AMELA ; A IGNER , M ANFRED (1)
(1) Institut für Verbrennungstechnik, DLR-Stuttgart, Germany contact: manfred.aigner@dlr.de
The DLR – Soot Generator serves as a precisely defined variable soot source, enabling the adjustment of particle mean diameters within a log-normal size distribution, ranging from 6nm to 250nm.
A computer-controlled gas sampler draws soot-laden exhaust gas through a high-efficiency quartz fiber filter, which captures over 99.9% of particles ranging from 6nm to 250nm The carbon accumulated on the filter is subsequently combusted in an oxygen-rich environment, and the concentration of carbon dioxide produced is measured using a Fourier Transform Infrared (FTIR) spectrometer By knowing the gas sampling volume, gas cell volume, and carbon dioxide concentration, the soot mass fraction can be accurately calculated.
The size distributions, number concentrations, and volume concentrations of soot are measured using a Scanning Mobility Particle Sizer (SMPS) system By combining the soot mass from the first experiment with the soot volume obtained from SMPS measurements, we calculate the soot density, which is determined by the mobility diameter of the fractal soot particles The ratio of graphite density to the calculated soot density reveals the fractal nature of the soot.
Overview of Results from the NASA Experiment to Characterize Aircraft Volatile
Aerosol and Trace Species Emissions (EXCAVATE)
A NDERSON , B RUCE E (1); W INSTEAD , E DWARD L.; H UDGINS , C HARLES H.;B RANHAM , S ANDY ; P LANT , J AMES V.; T HORNHILL ,
(1) NASA Langeley Research Center, Hampton, Virginia, USA contact: b.e.anderson@larc.nasa.gov
In January 2002, the EXCAVATE experiment at Langley Research Center aimed to assess aerosol and aerosol precursor production from the Langley B757 during ground operations This study, sponsored by NASA's Atmospheric Effects of Aviation Project and the Ultra Effect Engine Technology Program, sought to clarify uncertainties regarding jet fuel sulfur contaminants and their impact on local air quality Key objectives included measuring exhaust black carbon levels and gas ion densities based on plume age and engine power, evaluating the conversion of sulfur from S(IV) to S(VI), and analyzing the concentration and speciation of volatile aerosols and gas-phase acids Collaborators from NASA Langley, NASA Glen, the Air Force Research Laboratory, Aerodyne, and the University of Minnesota utilized fast-response instruments to collect data from both the Langley T-38 and B757 aircraft at varying sampling distances.
Preliminary observations of aircraft emissions at distances of 1 to 35 meters revealed high chemion densities in the exhaust, aligning with current microphysical models of aerosol formation Both aircraft emitted significant organic aerosols, especially at low power settings, while black carbon concentrations increased with engine power Notably, total particle emission indices for the B757 were approximately ten times higher at 25 to 35 meters compared to 1 meter behind the engine The concentration of sulfate aerosols was directly linked to fuel sulfur levels and increased significantly further downstream of the exhaust, indicating rapid sulfate particle growth within the exhaust plumes Additionally, aerosol concentrations and characteristics took several minutes to stabilize after changes in engine power, particularly when transitioning from high to low power during taxiing and landing.
SAE E-31 Committee on Aircraft Exhaust Emission Measurements and an Aerospace Information Report on the Measurement of Non-volatile Particle
M IAKE -L YE , R ICHARD C (1); Z ACCARDI , V INCE
(1) Aerodyne Research, Inc., Billerica, Massachusetts, USA contact: rick@aerodyne.com
Regulatory agencies are evaluating methods to measure particle emissions from aircraft engines, recognizing that existing regulations on visible smoke do not adequately address health and environmental impacts The ICAO Committee on Aviation Environmental Protection's Working Group 3 has sought technical assistance from the SAE E-31 committee to develop particulate characterization techniques for aircraft turbine engine certification The SAE E-31 committee, known for establishing aviation emission measurement protocols, is working on recommendations for an Aerospace Information Report (AIR) that will be reviewed by regulatory agencies and industry experts This AIR, currently under development, aims to enhance measurement practices and will eventually lead to an Aerospace Recommended Practice (ARP) detailing standards for particle emissions measurements, thus providing methodologies that are acceptable to regulatory bodies both in the US and internationally.
SO3 and H2SO4 in Exhaust of an Aircraft Engine: Measurements and Implications for Fuel Sulfur Conversion to S(VI) and SO3 to H2SO4
S OROKIN , A NDREY (1); K ATRAGKOU , E LENI (2); A RNOLD , F RANK (2); B USEN , R.(3); S CHUMANN , U LRICH (3)
(1) Central Institute of Aviation Motors, Moscow, Russia (2) Atmospheric Physics Division, MPI for Nuclear Physics, Heidelberg,
Germany (3) Institute for Physics of Atmosphere, DLR Oberphaffenhofen, Wessling, Germany contact: sorokin@ciam.ru
Gaseous sulfuric acid (GSA) produced by aircraft engines is significant for its role in forming aerosol particles that act as condensation nuclei for water vapor, influencing contrail and cloud formation GSA is generated through the oxidation of fuel sulfur to SO3, which then reacts with water vapor Key questions in this process include the proportion of S(VI) gases formed in the combustor and the fraction emitted as SO3 molecules, indicating an incomplete conversion of S(VI) to GSA in the exhaust plume.
This presentation highlights the first experimental estimation of the conversion efficiency (ε) of fuel sulfur to sulfur species (S(VI)), specifically SO3 and H2SO4, at the exhaust of aircraft gas turbine combustors The study found that ε is approximately 2.3 ± 1% when measured at an exhaust age of about 0.5 ms Additionally, the results indicate that SO3 molecules constitute a significant portion of S(VI) gases, with εA being less than 50%, and a notable conversion of SO3 to H2SO4 occurs within the sampling line, particularly under lower temperature conditions compared to the hot exhaust The alignment of ε values from this study and those obtained in exhaust measurements at a plume age of around 1 second suggests that S(VI) formation is inefficient in the post-combustor flow within aircraft engines.
Particle Emissions from Aircraft Engines - an Overview of the European Project
P ETZOLD , A NDREAS (1); W ILSON , C HRIS W.; A RNOLD , F RANK (2); B ALTENSPERGER , U RS ; F IEBIG , M ARKUS (1); F RITZSCHE , L UTZ ;
G IEBL , H EINRICH ; G YSEL , M ARTIN (3); H ITZENBERGER , R EGINA (4); H URLEY , C HRIS D.; K ATRAGKOU , E LENI (2); K URTENBACH ,
R ALF (5); M ADDEN , P AUL (6); N YEKI , S TEPHAN ; P UXBAUM , H ANS ; S CHUMANN , U LRICH (1); S TEIN , C LAUDIA ; V RCHOTICKY , S USI ;
(1) Institut fỹr Physik der Atmosphọre, DLR Oberpfaffenhofen, Wessling, Germany; (2) MPI fỹr Kernphysik, Heidelberg, Germany; (3) Paul Scherrer Institut, Laboratory of Atmospheric Chemistry, Villingen, Switzerland; (4) Institute for Experimental Physics, Wien, Austria;
(5) Bergische Universitọt Wuppertal, Physikalische Chemie, Wuppertal, Germany, (6) Rolls-Poyce, Derby, UK; (7) Institut fỹr
Verbrennungstechnik, DLR-Stuttgart, Germany contact: andreas.petzold@dlr.de
The European project PartEmis focused on measuring and predicting emissions from gas turbine engines, specifically examining how operating conditions and fuel sulfur content (FSC) affect the microphysical and chemical properties of particles emitted from a jet engine simulator This simulator included a real jet engine combustor and a Hot End Simulator (HES) designed to replicate the pressure and temperature profiles typical of a jet engine's turbine section.
The study investigated the emission properties of a combustor in two experiments The first experiment established baseline emission data, which served as boundary conditions for the second experiment examining the combined emissions of the combustor and HES Key aerosol properties analyzed included the number, size, and mass concentration of both primary combustion aerosol particles formed during combustion and secondary volatile particles generated in the cooling plume Additionally, the research explored the volatile fraction of internally mixed combustion particles, their hygroscopicity, and their potential for cloud condensation nuclei (CCN) activation, while also monitoring the emission of non-methane volatile organic compounds (NMVOCs).
The combustor-HES system was tested under two distinct inlet conditions, simulating the exhaust temperatures typical of both older and newer jet engines Various fuels with different Fuel Supply Characteristics (FSC) were utilized in the experiments.
Transport and impact on chemical composition
NOy in the UT/LS: A Source Attribution Study Utilising MOZAIC Measurements
C ROWTHER , R ICHARD (1); L AW , K ATHY (2); P YLE , J OHN (1); N EDELEC , P HILIPPE (3); S MIT , H ERMAN (4); V OLZ -T HOMAS ,
The Centre for Atmospheric Science at the University of Cambridge in the UK collaborates with several prominent institutions, including the Service d'Aeronomie at Université Pierre et Marie Curie in Paris, the Laboratoire d'Aerologie in Toulouse, France, and the Institut für Chemie der Belasteten Atmosphaere at FZ-Juelich in Germany For inquiries, please contact Richard Crowther at richard.crowther@atm.ch.cam.ac.uk.
The MOZAIC project combines measurements of ozone, water vapor, carbon monoxide, and nitrogen oxides from in-service Airbus aircraft with data from the Cambridge 3D global model (TOMCAT) to investigate NOy chemistry in the upper troposphere/lower stratosphere (UT/LS) This region experiences significant variability in chemical concentrations due to both biogenic and anthropogenic emissions, influenced by strong gradients across the tropopause The study will highlight the contributions of various emission sources, including in-situ aircraft emissions, to ozone levels and its production rates.
The TRADEOFF project: Goals and achievements
(1) Institutt for Geofysikk, Universitetet i Oslo, Oslo, Norway contact: ivar.isaksen@geofysikk.uio.no
The TRADEOFF project, funded by the EU and involving 10 European research groups, aims to assess the current and future impacts of a growing fleet of aircraft on atmospheric composition and climate This initiative focuses on the upper troposphere/lower stratosphere (UTLS) region, where increased air traffic and emissions could significantly alter NOx and ozone levels, contrail formation, and cirrus cloud distribution, thereby influencing climate forcing Key research areas include enhancing model performance through comparisons, studying chemical and dynamical processes in the UTLS, updating aircraft emission scenarios, and analyzing the effects of NOx emissions on ozone and methane lifetimes for present and future atmospheres Additionally, the project examines satellite observations of contrails and cirrus clouds in high-traffic corridors and evaluates their radiative forcing Specific modeling studies investigate potential trade-offs in air traffic management, such as optimizing flight times, cruising altitudes, and routes, as well as the implications of future supersonic aircraft operations in the lower stratosphere TRADEOFF will present new estimates on the impact of NOx on ozone and methane, alongside findings from contrail and cirrus cloud analyses, culminating in assessments of aircraft radiative forcing.
On the quality of chemistry-transport simulations in the upper troposphere/lower stratosphere region
B RUNNER , D OMINIK (1); S TAEHELIN , J OHANNES ; H AUGLUSTAINE , D IDIER (2); J OURDAIN , L INE ; R OGERS , H ELEN L.(3); K OEHLER ,
M ARCUS O.(3); P YLE , J OHN A.(3), B ERNTSEN , T ERJE K.(4); G AUSS , M ICHAEL (5); M EIJER , E RNST (6); VAN V ELTHOVEN , P ETER ;
G REWE , V OLKER (7); S AUSEN , R OBERT (7); P ITARI , G IANNI (8); M ANCINI , E VA ; I SAKSEN , I VAR S A.(5)
The article highlights key institutions involved in atmospheric and climate science research across Europe, including the Institute for Atmospheric and Climate Science at ETH Zurich, the Institut Pierre Simon Laplace in France, and the Centre for Atmospheric Science at the University of Cambridge in the UK Other notable organizations include CICERO in Norway, the Department of Geophysics at the University of Oslo, and the KNMI in the Netherlands Additionally, the Institute for Atmospheric Physics in Germany and the Dipartimento di Fisica at the Universita L'Aquila in Italy are mentioned For further inquiries, contact Dominik Brunner at dominik.brunner@iac.umnw.ethz.ch.
The EU-funded TRADEOFF project evaluated the performance of five European chemistry transport models (CTMs) and two general circulation models (GCMs) by comparing their outputs with observational data This study aims to enhance the understanding of how these models estimate the impact of aircraft emissions on atmospheric chemical composition, particularly in the upper troposphere/lower stratosphere (UT/LS) region, where air traffic emissions are concentrated and greenhouse gas ozone changes significantly affect climate change An extensive database of in-situ observations from 1995 to 1998 was created, incorporating data from key commercial and scientific aircraft campaigns, as well as ozone soundings The research includes a detailed comparison of simulated and observed trace gas concentrations in the challenging UT/LS region, which requires high vertical model resolution to accurately capture steep tracer gradients across the tropopause The study highlights the complexities of simulating convective processes that influence UT photochemistry by transporting surface pollutants upward, as well as the role of lightning in nitrogen oxide production Additionally, the production of OH radicals is linked to ozone, water vapor, and carbonyls, which are affected by vertical transport The findings will discuss the capabilities and limitations of the participating CTMs and GCMs, emphasizing the significant impact of small inaccuracies in the advection scheme on compound concentration levels in the UT/LS region.
Lightning NOx emissions and the impact on the effect of aircraft emissions -
Results from the EU-project TRADEOFF
(1) Institut fỹr Physik der Atmosphọre, DLR-Oberpfaffenhofen, 82234 Wessling, Germany contact: volker.grewe@dlr.de
Major sources of upper troposphere NOx emissions include lightning, contributing 5 TgN per year, and aircraft, accounting for 0.7 TgN per year The primary lightning NOx source is found at low latitudes, distinct from the mid-latitude region where aircraft emissions are prevalent However, the transport of tropical air masses to lower latitudes results in a mixing of air characteristics, combining both lightning and aircraft NOx emissions Simulations conducted with the global climate-chemistry model E39/C illustrate these interactions and allow for quantification of their effects The uncertainties surrounding the impact of aircraft emissions on atmospheric chemical composition, particularly ozone levels, stem from the poorly understood lightning NOx source in terms of its total strength and spatial distribution This issue will be emphasized and quantified through simulations that incorporate varying vertical distributions of the lightning NOx source.
Impact of Present-Day and Future Subsonic Aircraft Emissions on Tropospheric
Ozone and Associated Radiative Forcing of Climate
H AUGLUSTAINE , D IDIER (1); S TORDAL , F RODE (2); M YHRE , G UNNAR ; G AUSS , M ICHAEL (3); B ERNTSEN , T ERJE (4); I SAKSEN ,
The research collaboration involves several prestigious institutions: the Institut Pierre Simon Laplace in Gif-sur-Yvette, France; the Norwegian Institute for Air Research (NILU) in Kjeller, Norway; the Department of Geophysics at the University of Oslo; and the CICERO Center for International Climate and Environmental Research in Oslo, Norway For further inquiries, please contact hauglustaine@cea.fr.
Subsonic aircraft contribute substantial amounts of nitrogen oxides (NOx) to the upper troposphere and lower stratosphere, which can significantly alter ozone levels near the tropopause and impact climate radiative forcing Additionally, the increase in NOx from aircraft emissions enhances the presence of hydroxyl radicals (OH), resulting in a decreased atmospheric residence time for methane.
The EU-project TRADEOFF utilized advanced global atmospheric chemistry models to analyze current and future atmospheric composition changes projected for 2050 This study focuses on the alterations in NOx, O3, and OH, as generated by various chemical transport models The resulting chemical changes serve as inputs for a radiative transfer model, allowing for the quantification of ozone and methane's climate forcings Notably, while methane forcing partially mitigates the positive forcing linked to ozone on a global scale, the geographical and temporal distributions of these effects differ significantly, which will be illustrated in the findings.
Impact of aircraft NOx emissions: Effects of changing the flight altitude
G AUSS , M ICHAEL (1); G REWE , V OLKER (2); K OEHLER , M ARCUS (3)
(1) Department of Geophysics, University of Oslo, Norway; (2) Institute for Atmospheric Physics, DLR Oberpfaffenhofen, Wessling,
Germany; (3) Centre for Atmospheric Science, University of Cambridge, UK contact: michael.gauss@geophysikk.uio.no
The European TRADEOFF project has conducted model studies to explore how altitude affects the impact of NOx emissions from aircraft on atmospheric chemical composition This article presents findings from two chemical transport models, specifically the Oslo CTM.
The study utilizes two models, the Cambridge TOMCAT and the DLR E39C climate-chemistry model, to simulate present-day (2000) conditions under various global aircraft emission scenarios developed for TRADEOFF These scenarios include a base case at normal cruise altitudes, one with aircraft cruising 2000 feet higher, and another with aircraft cruising 6000 feet lower Since current cruise altitudes are influenced by fuel efficiency, both altitude increases and decreases lead to greater fuel consumption and elevated NOx emissions By normalizing the total NOx emissions to the base case, the research isolates the impact of changing cruise altitudes and the associated rise in fuel consumption.
Lower emission heights of NOx lead to reduced atmospheric residence times due to more effective wash-out processes at lower altitudes, resulting in a smaller increase in ozone compared to baseline scenarios Although enhanced fuel consumption partially offsets this effect, it remains minimal Conversely, operating at higher cruise altitudes increases the environmental impact of aircraft emissions, as pollutants released in the stratosphere experience significantly longer residence times.
CTM Simulation of Tropopause Ozone: Lessons from TRACE-P
P RATHER , M ICHAEL (1); H SU , J UNO (1); W ILD , O LIVER (2); S UNDET , J OSTEIN (3); I SAKSEN , I VAR (3)
(1) Earth System Science, University of California, Irvine, California, USA; (2) Frontier Reseach system for Global change, Yokohama,
Japan; (3) Institutt for Geofysikk, Universitetet i Oslo, Oslo, Norway contact: mprather@uci.edu
Accurate simulation of transport and mixing processes near the extra-tropical tropopause is essential for assessing aviation's atmospheric impact The recent TRACE-P campaign utilized extensive airborne measurements, including ozone Lidar and sondes, alongside high-resolution meteorological datasets to enhance chemistry-transport models (CTMs) Despite identifying some systematic biases, these high-resolution simulations (180 x 180 x 1 km) effectively replicate observed temporal and geographic patterns, including correlations of ozone and carbon monoxide in the tropopause region While validation tests have been conducted for only one region and season, they support tracer transport in the new model, allowing for comparisons with previous studies on aviation exhaust accumulation.
Improved mass fluxes in a global chemistry-transport model: implications for upper tropospheric chemistry
M EIJER , E RNST (1); V AN V ELTHOVEN , P ETER ; B REGMAN , B RAM ; S EGER , A RJO ; B RUNNER , D OMINIK (2)
(1) KNMI, De Bilt, Netherlands; (2) Inst for Atmospheric and Climate Science, ETH Zurich, Switzerland; contact: meijere@knmi.nl
Calculating the impact of aircraft emissions is challenging due to the majority of these emissions occurring in the upper-tropospheric and lowermost-stratospheric (UTLS) region Global chemistry-transport models struggle to accurately simulate trace gas concentrations in this area, which features significant cross-tropopause concentration gradients and mixing between the stratosphere and troposphere This region is crucial because radiative forcing is highly sensitive to greenhouse gas perturbations near the tropopause.
In the EU-project TRADEOFF, we developed a novel method for calculating mass fluxes from ECMWF data, addressing mass imbalances between mass transport and surface pressure tendencies found in many global chemistry-transport models This method allowed us to compute the mean age of air, which showed improved alignment with observed values, although the extra-tropical stratosphere's air still appeared too young Additionally, we analyzed ERA40 data, but found it poorly correlated with observed mean age of air, indicating potential issues with this dataset as noted by ECMWF.
Particles and clouds
Particles and Cirrus Clouds (PAZI) - Overview of Results 2000-2003
K ÄRCHER , B ERND (1); U S CHUMANN (1), M A IGNER (2), U S CHURATH (3), O S CHREMS (4), R S AUSEN (1), H K RUSE (5), C.
S CHILLER (6), S B ORRMANN (7), F A RNOLD (8), J F EICHTER (9), U L OHMANN (10), J S TRệM (11), T R OTHER (12), S.
B RINKOP (1), R B USEN (1), H F LENTJE (1), K G IERENS (1), J G RAF (1), W H AAG (1), J H ENDRICKS (1), H M ANNSTEIN (1), A.
P ETZOLD (1), P W ENDLING (1), P F RANK (2), P G ERLINGER (2), B N OLL (2), W S TRICKER (2), C W AHL (2), O M ệHLER (3), S.
S CHAEFERS (3), O S TETZER (3), F I MMLER (4), A D ệPELHEUER (5), M K RÄMER (6), A M ANGOLD (6), A W OLLNY (6), J.
(1) DLR-Institut fỹr Physik der Atmosphọre, Oberpfaffenhofen, Germany (2) DLR-Institut fỹr Verbrennungstechnik, Stuttgart, Germany
The article highlights various prominent research institutions focused on meteorology and atmospheric sciences across Europe and Canada Notable organizations include the Forschungszentrum Karlsruhe's Institute for Meteorology and Climate Research in Germany, the Alfred Wegener Institute's Section for Physics and Chemistry of the Atmosphere in Bremerhaven, and the DLR Institute for Propulsion Technology in Cologne Additional key contributors are the Forschungszentrum Jülich's Institute for Stratospheric Chemistry, the University of Mainz and Max Planck Institute for Chemistry's Department of Cloud Physics, and the Max Planck Institute for Nuclear Physics in Heidelberg The Max Planck Institute for Meteorology in Hamburg and Dalhousie University's Department of Physics and Atmospheric Science in Halifax, Canada, along with the Institute of Applied Environmental Research at Stockholm University in Sweden, further enhance the global collaboration in atmospheric research Lastly, the DLR German Remote Sensing Data Center plays a crucial role in providing valuable data for environmental studies.
Oberpfaffenhofen, Germany contact: bernd.kọrcher@dlr.de
PAZI is a national research initiative funded by the German Secretary of Education and Research (BMBF) and conducted in collaboration with European Commission projects INCA, PARTEMIS, and PARTS The project focuses on the interaction between aerosol particles and cirrus clouds, particularly examining the effects of aviation-produced aerosols and contrails on atmospheric composition, radiation, clouds, and climate This overview highlights key research findings from the project's initial phase, spanning from 2000 to 2003.
This article highlights key issues related to black carbon (BC) particles, including their formation and evolution in burners and jet engines, and the physico-chemical characterization of aircraft-produced BC It discusses the freezing properties of liquid and BC particles, along with the global atmospheric distribution of BC from various sources The article also examines differences in cirrus properties between clean and polluted air masses, and explores correlations between air traffic and cirrus cloud cover based on satellite observations Additionally, it addresses aerosol-cirrus interactions, parameterization of cirrus cloud formation, and the representation of ice supersaturation and cirrus clouds in climate models, along with their potential climatic impacts.
Open research questions, strategic goals, and the organisation of the follow-on project PAZI-2, planned for the period 2004-2008, are briefly described
Upper tropospheric aerosol formation inside and outside aircraft wakes: new findings from mass spectrometric measurements of gaseous and ionic aerosol precursors and very small aerosols
(1) Max-Planck-Institut für Kernphysik, Heidelberg, Germany contact: Frank.Arnold@mpi-hd.mpg.de
This article examines recent mass spectrometric measurements of upper tropospheric gaseous and ionic aerosol precursors, as well as very small aerosol particles found inside and outside aircraft wakes Key parameters analyzed include condensable gases, particularly sulfuric acid and its precursor SO2, positive and negative cluster ions, electrically charged small soot particles, and positively and negatively charged volatile aerosol particles with diameters less than 3 nm, which are too small for detection by condensation particle counters.
Recent measurements indicate that new volatile aerosol particles form and grow both within and outside of aircraft wakes These particles, originating from aircraft and the surrounding upper troposphere, primarily undergo condensational growth through the absorption of condensable gases These gases are photochemically produced in the upper troposphere, with their precursors originating from ground-level sources, many of which are linked to human activities.
Single Particle Black Carbon Measurements in the UT/LS
B AUMGARDNER , D ARREL (1); K OK , G REG (2); R AGA , G RACIELA (1); D ISKIN , G LENN (3); S ACHSE , G LENN (3)
(1) CCA/UNAM, Mexico City, Mexico; (2) 2400 Central Avenue, Suite A, Boulder, Colorado, USA; (3) NASA Langley Research Center,
Langley AFB, Virginia contact: darrel@servidor.unam.mx
Black carbon (BC) aerosols in the upper troposphere and lower stratosphere (UT/LS) have been sparsely measured, with key studies by Pueschel et al (1992) and Blake and Kato (1995) forming the foundation for global BC loading estimates in this region In winter 2003, the introduction of the single particle soot photometer (SP2) allowed for new measurements of light-absorbing components of individual particles from the NASA DC-8, enhancing our understanding of BC in the UT/LS.
Between January 24 and February 6, 2003, the SP2 instrument conducted measurements on seven flights as part of the SAGE III Ozone Loss and Validation Experiment (SOLVE II) Most of these flights took place north and west of Kiruna, Sweden (67.8N, 20.3E), at altitudes exceeding 10 kilometers, with the tropopause typically located within this range.
9 and 10 Km, so the measurements were in stratospheric air during most of each flight The focus of SOLVE
The research focused on studying ozone loss within the polar vortex, with most flight time dedicated to exploring various regions of the vortex Several flights involved spiral descents, allowing for the collection of vertical profiles of particle and gas species.
The BC fraction of particles varies between 4% and 16%, peaking near the tropopause and remaining relatively stable between 6 and 9 km A strong correlation between carbon monoxide (CO) levels and the BC fraction indicates that combustion is a likely source of BC, with CO suggesting vertical transport from surface sources Previous estimates by Pueschel et al (1992) indicated that BC constituted only 0.03% of total aerosol number concentration in the upper troposphere/lower stratosphere (UT/LS), while current findings reveal BC fractions of 5-20%, indicating concentrations 100-400 times higher than earlier estimates This suggests that global BC loading may be significantly underestimated, highlighting the need for further analysis to assess the environmental implications of these elevated levels.
Ice-nucleating ability of soot particles in UT/LS
S UZANNE , J EAN (1) ; F ERRY , D.; P OPOVICHEVA , O.B.(2); S HONIJA ,N.K.
(1) CRMC2-CNRS, Campus de Luminy, Marseille, France; (2) Department of Microelectronics, Institute of Nuclear Physics, Moscow
State University, Russia contact: suzanne@crmc2.univ-mrs.fr
Aircraft-generated soot aerosols are considered key contributors to the formation of ice in contrails and cirrus clouds This study examines the morphology, microstructure, and water adsorbability of laboratory-produced kerosene soot, which serves as a surrogate for aircraft soot The research aims to establish a correlation between the porosity of the soot's morphology and its ability to nucleate ice.
Quasi-Elastic Neutron Scattering (QENS) and neutron diffraction (ND) have effectively demonstrated the dynamics and structure of water and ice within a porous soot network, tracking changes in temperature (T) and relative humidity (RH) from plume conditions to UT/LS environments QENS spectra indicate a gradual freezing of water below the bulk melting temperature, while the observed decrease in translational and rotational diffusion coefficients with temperature is linked to the nucleation of supercooled water in constrained micro and supermicropores This phenomenon results in a depression of the homogeneous nucleation point, allowing water to remain in a supercooled state below 204K Additionally, ND spectra reveal a coexistence of amorphous ice, likely within the soot pores, alongside ice Ih present on the soot surface.
In the latest plume, water molecules adsorb onto primary active centers, filling soot micropores (~0.5 nm) where they remain localized As the plume cools and relative humidity reaches ~70-80%, soot supermicropores (~2 nm) become fully saturated This leads to capillary condensation in soot mesopores and multilayer growth on the external surface Under saturation conditions, approximately 30% of the adsorbed water on soot transforms into ice, primarily within the mesopores and on the surface However, ice nucleation and growth are inhibited in the micro and supermicropores, as around 35% of the water remains in a liquid state under these conditions.
Upon evaporation of the aircraft contrail, new ice forming nuclei containing the soot particles appear in the
At a temperature of approximately 220K, the presence of 75% ice within soot pores enhances the soot's ability to serve as secondary ice nuclei for cirrus clouds Additionally, around 15% of the water trapped in soot supermicropores may remain in a liquid state even at low stratospheric temperatures near 200K.
Experimental investigation of homogeneous and heterogeneous freezing processes at simulated UTLS conditions
M ệHLER , O TTMAR (1); S CHNAITER , M ARTIN ; W AGNER , R OBERT ; S CHURATH , U LRICH ; M ANGOLD , A LEXANDER (2); K RÄMER ,
(1) Forschungszentrum Karlsruhe, IMK-AAF, Karlsruhe, Germany; (2) Forschungszentrum Juelich, Institut für Chemie und Dynamik der
Geosphọre I: Stratosphọre, Jỹlich, Germany contact: Ottmar.Moehler@imk.fzk.de
Ice nucleation (IN) in the upper troposphere and lower stratosphere (UTLS) can occur through homogeneous freezing of solution droplets at temperatures below 240 K or via heterogeneous processes involving ice nuclei Homogeneous IN requires high ice supersaturations of up to 60%, commonly found in the upper troposphere, where strong updrafts promote cirrus cloud formation Conversely, at lower updraft velocities, heterogeneous ice nuclei, such as soot particles from aircraft emissions, can activate at lower supersaturation levels This leads to the growth of pristine ice crystals through water uptake, which limits maximum supersaturation below the homogeneous freezing threshold, potentially explaining the presence of optically thin cirrus layers with fewer, larger ice particles Research conducted in the AIDA (Aerosol Interaction and Dynamics in the Atmosphere) chamber at Forschungszentrum Karlsruhe simulates cirrus conditions to investigate ice formation processes The onset of freezing is monitored through laser radiation measurements sensitive to aspherical ice particles, while relative humidity is calculated from total water concentration data Additionally, ice particle characteristics, including number concentration and size, are assessed using optical particle counters, and in situ FTIR extinction spectra are employed to analyze growing and evaporating ice crystals This paper reviews recent studies on the formation, growth, and optical properties of ice crystals in various aerosol systems, including sulphuric acid droplets and soot particles coated with sulphuric acid and ammonium sulfate.
Detailled Modelling of Cirrus Cloud - an intercomparison of different approaches for homogeneous nucleation
M ONIER , M ARIE (1); W OBROCK , W OLFRAM ; F LOSSMANN , A NDREA
(1) Laboratoire de Météorologie Physique, Aubière, France contact: monier@opgc.univ-bpclermont.fr
We created a cirrus model that incorporates detailed microphysics, including homogeneous nucleation, deposition on ice crystals, and riming of supercooled droplets This model utilizes a two-dimensional particle distribution, enabling the retention of information on aerosol particles that serve as cloud condensation nuclei (CCN) and influence the solute concentration within the droplets.
Mitigation
On the potential of the cryoplane option to reduce aircraft climate impact
P ONATER , M ICHAEL (1); M ARQUART , S USANNE (1); S TRệM , L INDA (1); S AUSEN , R OBERT (1); G IERENS , K LAUS (1); H ĩTTIG ,
(1) Institut fỹr Physik der Atmosphọre, DLR-Oberpfaffenhofen, Wessling, Germany; (2) Institut fỹr Luft- und Raumfahrt, TU-Berlin,
Germany contact: michael.ponater@dlr.de
Switching to alternative fuels, such as liquid hydrogen, presents a viable technological solution to mitigate the climate impact of air traffic Our research assesses the quantitative potential of this transition, considering the projected growth in air traffic from 1990 to 2050 alongside a technological shift occurring between 2015 and 2050.
The study investigates the impact of reduced CO2 and NOx emissions, along with changes in contrail radiative effects due to variations in coverage and optical properties Utilizing both a microphysical process model and an advanced climate model, researchers aimed to quantify the specific climate impact of cryoplane contrails The findings indicate a potential reduction in radiative forcing from aircraft emissions by approximately 25% by 2050 with the introduction of cryoplanes, with estimates varying between 16% and 29% based on the pace of technological advancements However, due to scientific uncertainties, this range could extend from 14% to 40%.
Some further sources of uncertainty like cirrus cloud changes or possible CO2 emissions from the liquid hydrogen production process have not been included in the current estimate.
Tradeoffs in Contrail and CO 2 Radiative Forcing by Altered Cruise Altitudes
L EE , D AVID S.(1); S AUSEN , R OBERT (2); M ARQUART , S USANNE (2); F ICHTER , C HRISTINE (2); N ORMAN , P ETER (3)
(1) Department of Environmental and Geographical Sciences, Manchester Metropolitan University, Manchester, UK;(2) Institute for
Atmospheric Physics, DLR-Oberpfaffenhofen, Germany; (3) QinetiQ, Farnborough, UK contact: mlee110@compuserve.com
The TRADEOFF project, part of the 5FP EU initiative, investigated the effects of modified cruise altitudes on CO2 and NOx emissions across the global fleet By adjusting cruise altitudes by +2,000, -2,000, and -6,000 feet, researchers conducted a parametric study that included a new contrail coverage calculation based on distance traveled instead of fuel consumption, using the GCM ECHAML39(DLR)/CHEM model The study revealed that lowering the cruise altitude by 6,000 feet resulted in a few percent increase in CO2 emissions while significantly reducing linear contrail coverage by 43% and radiative forcing by 45%.
Policies for Mitigating Contrail Formation from Aircraft
N OLAND , R OBERT (1); T OUMI , R ALF (2); W ILLIAMS , V ICTORIA (3)
(1) Centre for Transport Studies, Dept of Civil & Environmental Engineering, Imperial College London, London, UK; (2) Dept of Physics,
Imperial College London, London, UK; (3) Transport Studies Group, University of Westminster, London, UK contact: r.noland@imperial.ac.uk
To reduce aircraft contrail formation, implementing altitude restrictions based on ambient atmospheric conditions is a viable approach Contrails are more likely to form in colder temperatures and higher humidity, prompting research into cruise altitude policies A simulation model of European airspace assessed seasonal altitude restrictions, revealing winter limits of 24,000 feet and summer limits of 31,000 feet The findings indicated minimal increases in carbon emissions and travel times, but significant impacts on air traffic controller workload Further analysis of long-haul North Atlantic flights suggested that while altitude restrictions remain feasible, they are less effective compared to short-haul flights The study highlights the need for additional research and policy considerations.
J OHN G REEN contact: greens@woburnhc.freeserve.co.uk
In the next century, environmental concerns will significantly shape aircraft design, as reducing the impact per passenger kilometer becomes crucial for the growth of air travel Among the main environmental issues—noise, airport air pollution, and climate change—the latter poses the greatest long-term challenge Aircraft contribute to climate change primarily through CO2 and NOX emissions, as well as persistent contrails, with the latter two presenting the most viable targets for reduction Strategies to mitigate these impacts may inadvertently increase CO2 emissions, suggesting that regulations should be carefully crafted to balance these factors While addressing CO2 emissions remains a vital goal, advancing aircraft design to lower fuel consumption is essential, highlighting the importance of new technologies and innovative design concepts in achieving this objective.
Poster Session 1: Engine Emissions and Plume Processes / Transport and impact on chemical composition
CCN Activation of Jet Engine Combustion Particles During PARTEMIS
H ITZENBERGER , R EGINA (1); G IEBL , H EINRICH (1); P ETZOLD , A NDREAS (2); G YSEL , M ARTIN (3); N YEKI , S TEFAN (3);
W EINGARTNER , E RNEST (3); B ALTENSPERGER , U RS (3); W ILSON , C HRISTOPHER W (4)
The article highlights collaborations among several prestigious institutions in atmospheric research, including the Institute for Experimental Physics at the University of Vienna, the Institute for Atmospheric Physics at DLR in Oberpfaffenhofen, the Laboratory of Atmospheric Chemistry at the Paul Scherrer Institut in Switzerland, and the Centre for Aerospace Technology at QinetiQ in the UK For inquiries, contact Regina Hitzenberger at regina.hitzenberger@ap.univie.ac.at.
The EU project PartEmis investigated the microphysical properties of jet engine exhaust particles for fuels with varying sulphur content (FSC 50, 410, and 1280 µg/g) under conditions simulating both old and modern aircraft This study focused on the particles' capability to act as cloud condensation nuclei (CCN) at water vapor supersaturations of around 0.7%, slightly higher than the typical 0.5% for stratus cloud formation CCN measurements were conducted using a static thermal diffusion chamber developed at the University of Vienna, which was calibrated for counting efficiency and supersaturation The relative concentration of CCN, or activation ratio, was analyzed across different operational conditions and FSC levels, revealing increases in activation ratios as FSC rose, with notable differences between old and modern conditions The activation behavior of exhaust particles was modeled using Kelvin theory, Kähler theory, and a semi-empirical model incorporating measured hygroscopicities, with sulphuric acid assumed as the soluble material Comparisons of the modeled and measured activation behaviors indicated that the semi-empirical model provided the best agreement.
The research conducted under EU contract # G4RD-CT-2000-00207 received additional support from the Swiss Bundesamt für Bildung und Wissenschaft (99.0632) The development of the CCN counter was funded by the Fonds zur Förderung der wissenschaftlichen Forschung in Österreich (P 131 43 - CHE) The authors express their gratitude to the QinetiQ test-rig operation crew for their invaluable assistance during the experiments.
Gas and Aerosol Chemistry of Commercial Aircraft Emissions Measured in the
W ORSNOP , D OUGLAS R.; M IAKE -L YE , R ICK (1); B OUDRIES , H ACENE ; W ORMHOUDT , J ODY ; A NDERSON , B RUCE (2)
(1) Aerodyne Research, Inc., Billerica, Massachusetts, USA; (2) NASA, Langley Research Center, Hampton, Virginia, USA contact: rick@aerodyne.com
An aerosol mass spectrometer (AMS) and tunable infrared laser absorption spectrometer (TILDAS) were deployed to sample emissions from the Langley B757 as part of the NASA EXCAVATE program in January,
In 2002, aerosol emissions were measured at various distances (1, 10, 25, and 35 meters) behind the RB211 engine using the Aerosol Mass Spectrometer (AMS), while gas emissions were sampled at 1 and 10 meters with the Tunable Infrared Laser Differential Absorption Spectroscopy (TILDAS) The engine power was adjusted from idle to near take-off thrust, and sulfur content in the fuel was varied The AMS effectively samples submicron aerosols (30 to 1000 nm) and analyzes their chemical composition through thermal vaporization and mass spectrometric techniques, allowing for real-time quantification of volatile components like organic carbon and sulfate, though it does not detect refractory elements such as elemental carbon Meanwhile, the TILDAS employs direct absorption spectroscopy in the near-infrared range to monitor specific gas-phase species, including NO, NO2, HONO, and SO2, with high sensitivity and rapid time resolution.
The study found that the size and mass loading of fine aerosols (30nm diameter) increased with distance from the engine, with sulfate and organic aerosols mixed in small and large modes (~60 and 200nm aerodynamic diameter, respectively) Notably, organic carbon (OC) loading was approximately 50 times greater than that of sulfate, with the OC mass spectrum resembling lubricant oil from the engine, while sulfate was primarily pure sulfuric acid This increase in aerosol loading is attributed to the condensation of vapor species as the plume cools and ages A significant rise in OC aerosol loading, up to 1000 times during the transition from low to high engine power settings, highlights the implications for airport emissions from aircraft The findings from the Aerosol Mass Spectrometer (AMS) will be compared with other physical aerosol measurements, addressing potential inlet effects, especially directly behind the engine.
TILDAS measurements aimed to quantify HONO emissions indices (EIs) as the RB211 engine was tested across its EXCAVATE operating range HONO is generated in the post-combustor flow path, influenced by the availability of OH radicals as temperatures decrease in the turbine and tailpipe This compound serves as a sensitive indicator of oxidative processes occurring after combustion, with its concentrations varying based on the temperature history within the engine's hot sections, which fluctuate with different operating conditions Notably, a clear correlation with engine operation was observed, as HONO concentrations increased to over 2 ppmv at the maximum power setting.
Sulfur (VI) in the simulated internal flow of an aircraft gas turbine engine: first measurements during the PartEmis project
K ATRAGKOU , E LENI (1); W ILHELM , S.; A RNOLD , F.(1); W ILSON , C.W.(2)
(1) Max Planck Institute for Nuclear Physics, Heidelberg, Germany; (2) QinetiQ, Centre for Aerospace Technology, Farnborough, UK contact: eleni.katragkou@mpi-hd.mpg.de
For the first time, gaseous S(VI) (SO3+H2SO4) was measured using chemical ionization mass spectrometry (CIMS) in a simulated aircraft gas turbine flow during the PartEmis 2002 campaign The abundance ratio e=S(VI)/St was determined across three pressure stages (Low, Intermediate, and High) under two engine test conditions, reflecting old and modern aircraft cruise scenarios In the old cruise condition at the Low Pressure stage with FSC = 1270 ppm, an e of 1.4±0.7% was recorded, while the modern cruise condition yielded an e of 2.3±1.2%, indicating a correlation between e and combustor exit temperature, pressure, and fuel flow These findings align with previous direct measurements of e in aircraft gas turbine exhaust plumes but are lower than some earlier indirect estimates based on aerosol volatility and SO2 measurements The results suggest a relatively small e in the few percent range, highlighting significant implications for volatile aerosol formation and soot particle activation in aircraft wakes, as well as their influence on contrail and cloud formation.
Emission of Volatile and Non-Volatile Ultrafine Particles from a Combustion Source
F IEBIG , M ARKUS (1); F RITZSCHE , L UTZ ; S TEIN , C LAUDIA ; N YEKI , S TEPHAN ; P ETZOLD , A NDREAS (1)
(1) Institut fỹr Physik der Atmosphọre, DLR Oberpfaffenhofen, Wessling, Germany contact: markus.fiebig@dlr.de
The formation of volatile nanoparticles from gaseous precursors in the cooling exhaust of combustion sources is a recognized phenomenon, particularly in aviation emissions during cruise, which may contribute to sulfuric acid particles in the upper troposphere The size of these nucleating particles is largely influenced by atmospheric relative humidity, typically remaining under 20 nm in diameter Additionally, non-volatile nanoparticles with diameters around 5 nm have been identified in soot-forming flames, serving as precursors to combustion aerosol particles (soot) Both volatile and non-volatile nanoparticles have been detected in jet engine combustor exhaust, prompting investigations into how combustor operating conditions and fuel sulfur content (FSC) affect their formation through experimental methods and modeling studies.
The measurement of nanoparticles (D < 20 nm) was conducted using a multi-channel Condensation Particle Size Analyzer (CPSA) on diluted exhaust gas, achieving size resolution in the D < 20 nm range The CPSA provides number concentrations for size bins of D = 4-7 nm, 7-9 nm, 9-20 nm, and >20 nm Additionally, the size distribution of combustion aerosols (D 10 nm) was assessed with a Scanning Mobility Particle Sizer (SMPS), while the mixing state of the total aerosol was analyzed for sizes D.
= 15nm, 30 nm, 50 nm, and 80 nm by using a Differential Mobility Analyzer combined with a thermodenuder system
At low and medium fine particle size concentrations (FSC), the smallest size class particles are approximately 20 times less frequent than combustion aerosol particles, whereas at high FSC, their occurrence increases to up to seven times more than combustion aerosol particles Notably, the presence of particles in the size ranges of 7-9 nm and 9-20 nm remains largely unaffected by changes in FSC Volatility analysis of particles smaller than 20 nm indicates that volatile condensation particles are primarily made up of sulfuric acid, while non-volatile nanoparticles are likely composed of carbonaceous materials.
Kinetics of Binary Nucleation in Aircraft Exhaust Plume
S OROKIN , A NDREY (1); V ANCASSEL , X AVIER (2); M IRABEL , P HILIPPE (2)
(1) Central Institute of Aviation Motors, Moscow, Russia, (2) Centre de Géochimie de la Surface, CNRS and Université Louis Pasteur,
Strasbourg, France contact: sorokin@ciam.ru
Particles and Clouds / Mitigation
Aerosol properties measured in situ in the free troposphere and tropopause region at midlatitudes
M INIKIN , A NDREAS (1); P ETZOLD , A NDREAS (1); F IEBIG , M ARKUS (1); H ENDRICKS , J OHANNES (1); S CHRệDER , F RANZ (1)
(1) Institut fỹr Physik der Atmosphọre, DLR Oberpfaffenhofen, Wessling, Germany contact: andreas.minikin@dlr.de
In recent years, the DLR Falcon 20, a German twin-jet research aircraft, has conducted experiments to analyze aerosol properties in the troposphere and tropopause, reaching altitudes of up to 13 km Using condensation particle counters, researchers measured total aerosol number concentrations for Aitken mode and ultrafine particles, with lower cut-off diameters ranging from 3 to 15 nm Additionally, they assessed the fractionation of volatile, semi-volatile, and refractory particles for specific datasets The concentration of accumulation mode particles and aerosol size distributions were determined through optical aerosol spectrometer measurements, specifically with PMS PCASP-100X and FSSP-300 probes This report presents mean vertical profiles of aerosol properties in the upper troposphere and statistics on aerosol concentration and size distributions from various campaigns across Europe, highlighting differences in marine and continental locations and the influence of anthropogenic pollution.
Hygroscopicity and wetting of aircraft engine soot and its surrogates:
P OPOVICHEVA , O LGA (1); P ERSIANTSEVA , N.; S HONIA , N.;Z UBAREVA , N.; L OKHOVITSKAY , K; S UZANNE , J.(2); F ERRY , D;
(1) Department of Microelectronics, Institute of Nuclear Physics, Moscow State University, Moscow, Russia; (2) CRMC2-CNRS,Campus de Luminy, Marseiile, France contact: OPopovitcheva@mics.msu.su
Research highlights the significant role of aircraft-generated soot particles in the formation of contrails and cirrus clouds in the upper troposphere However, the ice nucleating properties of exhaust soot remain largely unknown due to the challenges in obtaining clear evidence of their involvement in ice formation through in situ measurements To address this gap, a study utilized a typical aircraft engine combustor, burning aviation kerosene under cruise conditions, to produce and analyze engine soot This research focused on characterizing the properties of soot that influence cloud condensation nucleus (CCN) formation, comparing soot from sulfur-free fuel combustion with laboratory-made kerosene flame soots as proxies for atmospheric black carbon (BC) aerosols.
This study investigates the soot wetting and hydration properties to explore potential pathways for cloud condensation nuclei (CCN) formation in the upper troposphere (UT) The microstructure and chemical composition of soot significantly affect its wetting characteristics Engine soot is composed of a blend of graphite flakes and amorphous low surface area particles, with water/ice contact angles ranging from 50 to 80 degrees The optimal wettability is observed in engine soot, with a contact angle of approximately 50 degrees, attributed to a considerable water-soluble fraction (WSF) of at least 4.4 wt% and volatile compounds around 17% The primary component of the WSF is sulfate, identifiable in FTIR spectra Notably, engine soot exhibits high hygroscopicity, capable of adsorbing about 20 monolayers of water at 240K, making it effective as contrail condensation nuclei at low water supersaturations within the plume.
Combustor and kerosene soots exhibit θ values of approximately 63° and 80°, indicating their role as insoluble black carbon (BC) particles in the upper troposphere (UT) These particles have a monolayer of adsorbed water on their surfaces, characterized by an intermediate polarity The inverse Kelvin effect suggests that the agglomerated structure of soot enhances the heterogeneous nucleation process, facilitating water condensation in the interparticle cavities between primary soot particles This mechanism is crucial for ice nucleation on insoluble carbonaceous particles in the UT and helps estimate the critical ice supersaturations (Sc) required for particle growth, with values found to be around 6.2% for combustor soot and 17.6% for kerosene soot at 0K The analysis of Sc provides insights into the wetting characteristics of these soot particles.
BC particles are required for the cirrus cloud formation in the ice - saturated regions of the UT.
Ice Water Content of Cirrus Clouds and its Dependency on different Types of
M ANGOLD , A LEXANDER (1); B ĩTTNER , S IMONE (2); E BERT , V OLKER (3); G IESEMANN , C ARSTEN (3); K RÄMER , M ARTINA (1);
M ệHLER , O TTMAR (2); S AATHOFF , H ARALD (2); S CHURATH , U LRICH (2); S TETZER , O LAF (2); T EICHERT , H OLGER (3); W AGNER ,
(1) Forschungszentrum Jỹlich, Institut fỹr Chemie und Dynamik der Geosphọre I (ICG-I): Stratosphọre, Jỹlich, Germany; (2) Forschungszentrum Karlsruhe, Institut fỹr Meteorologie und Klimaforschuửng, IMK-AAF, Karlsruhe, Germany; (3) Universitọt
Heidelberg, Physikalisch-Chemisches Institut; Heidelberg; Germany contact: a.mangold@fz-juelich.de
The impact of aerosols on cloud microphysics is crucial due to its relationship with climate forcing While some studies have focused on liquid water clouds, knowledge regarding ice clouds is still limited Accurate modeling of ice particle formation in cirrus clouds requires reliable parameterization of how available water is distributed among gas, liquid (aerosol), and solid phases Currently, there is a lack of experimental data that offers precise measurements of both the gas phase and ice water content.
We performed laboratory measurements to investigate both homogeneous and heterogeneous ice nucleation, as well as water partitioning under UT cirrus cloud conditions These experiments were conducted at varying temperatures and with different types of aerosol particles in the AIDA aerosol chamber at IMK-AAF.
The formation of ice particles was facilitated by achieving ice supersaturation through quasi adiabatic volume expansion via controlled pumping The initiation of freezing was identified by measuring the depolarization of scattered laser light with high sensitivity and time resolution Total water content, including both gas and condensed phases, was measured using the Lyman-alpha fluorescence hygrometer (FISH) from FZJ, ICG-I Concurrently, in situ gas phase water concentration was directly assessed through absorption at 1370nm using a tuneable diode laser (TDL) from the University of Heidelberg and IMK-AAF Additional insights into the ice phase, such as number concentration and size distribution of ice particles, were obtained through in-situ multi-path FTIR extinction spectroscopy and an optical particle counter, allowing for comprehensive measurement of water partitioning during ice nucleation experiments.
This article presents findings on the evolution of ice water content from the onset of freezing to the completion of cloud formation Ice nucleation experiments were carried out at temperatures below 235 K, utilizing various aerosols as ice nuclei, including pure mineral dust, soot coated with sulfuric acid and ammonium sulfate, as well as solution droplets of sulfuric acid and ammonium sulfate.
3D simulation of cirrus formation from airplane contrails
(1) Danish Meteorological Insitute, Copenhagen, Denmark contact:jkn@dmi.dk
A new Eulerian microphysical 3D-cirrus cloud model (MPC) has been developed, featuring a comprehensive microphysical representation of liquid and solid phase cloud particle size distributions This model incorporates essential processes such as nucleation, melting, condensation, evaporation, and sedimentation In this study, the MPC is utilized to simulate various scenarios involving the formation of contrails.
Heterogeneous nucleation effects on cirrus cloud coverage
(1) Institut fỹr Physik der Atmosphọre, DLR-Oberpfaffenhofen, Wessling, Germany contact: klaus.gierens@dlr.de
Current aircraft engines emit significant aerosol particles into the atmosphere, even in the absence of contrails, which may contribute to heterogeneous cirrus cloud formation at lower ice-supersaturations than those required for homogeneous nucleation This indirect effect is believed to increase average cirrus cloud coverage compared to a scenario without aircraft emissions, such as a fleet of LH2-driven airplanes However, this perspective oversimplifies the situation, as several competing effects must be considered Heterogeneously formed cirrus clouds are likely to be optically thinner due to fewer ice crystals and lower maximum supersaturation during nucleation Additionally, once a heterogeneous cloud forms, the supersaturation is depleted, preventing the formation of a homogeneous cloud that would have occurred otherwise Moreover, the lifetimes of clouds formed through heterogeneous processes may differ systematically from those formed homogeneously Results from the ECHAM model, which incorporates new parameterizations for cirrus coverage from both processes, illustrate these potential effects Unfortunately, significant uncertainty remains regarding many involved parameters, making a comprehensive assessment of the climatic impact of the indirect effect currently unattainable.
Contrail Coverage over the USA Derived From MODIS and AVHRR Data
P ALIKONDA , R ABINDRA (1); P HAN , D UNG ; M INNIS , P ATRICK (1)
(1) NASA Langley Research Center Hampton, Virginia, USA contact: r.palikonda@larc.nasa.gov
Contrails contribute to the formation of additional cirrus clouds, impacting the climate's radiation budget Assessing contrail coverage and optical properties is essential for understanding the climatic effects of air traffic Recent estimates of contrail coverage over the USA have relied on NOAA-16 afternoon overpass data, while earlier studies utilized data from two satellites during 1993-94 With around 14,000 daily flights in the USA, commercial air traffic peaks from 0600 LT to just before midnight, leading to contrail lifetimes of less than 4-6 hours This suggests that most contrail coverage dissipates by the next day, which should be reflected in contrail properties However, initial findings using NOAA-15 morning overpasses indicate that afternoon analyses may underestimate contrail coverage due to overlapping contrails from morning flights To better understand diurnal variations in contrail coverage, this study employs data from multiple satellites, including NOAA-12, NOAA-15, NOAA-17, Terra, Aqua, and NOAA-16, analyzing multispectral data from AVHRR and MODIS instruments Comparisons of instrument sensitivities ensure that observed variations are not artifacts, with preliminary results highlighting daily contrail variations and more detailed analyses focusing on NOAA-15 and NOAA-16 data.
Contrail Coverage over the North Pacific From MODIS and AVHRR Data
M INNIS , P ATRICK (1); P ALIKONDA , R ABINDRA (1); A YERS , J K IRK
(1) NASA Langley Research Center, Hampton, Virginia, USA contact: p.minnis@larc.nasa.gov
Since the 1970s, there has been a notable increase in cirrus cloud cover over the North Pacific, attributed partly to rising relative humidity and likely influenced by contrails from transoceanic air traffic To accurately assess the impact of linear contrails on this increase, high-resolution satellite data analysis is essential The Advanced Very High Resolution Radiometer (AVHRR) has been capturing 1-km multispectral data from NOAA satellites since the 1980s, although most available data over vast ocean regions is limited to the 4-km Global Area Coverage dataset Additionally, NASA's Terra and Aqua satellites have been operational since March, contributing to ongoing observations.
From August 2000 to August 2002, the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Terra and Aqua satellites captured and archived global multispectral data at resolutions ranging from 0.25 to 1 km An automated algorithm was employed to analyze 1-km MODIS data and select AVHRR datasets to quantify contrail properties over the North Pacific, including areal coverage, optical depth, ice particle size, and radiative forcing These derived properties were then compared to similar metrics obtained from continental United States data to assess differences between contrails formed over marine and continental regions, with preliminary statistics and comparisons provided.
Survey of Cirrus properties from Satellite retrievals using TOVS and AVHRR observations
(1) Laboratoire de Mộtộorologie Dynamique, Ecole Polytechnique, Palaiseau, France; (2) Institut fỹr Physik der Atmosphọre, DLR-
Oberpfaffenhofen, Wessling, Germany contact: stubenrauch@lmd.polytechnique.fr
Since 1979, TOVS instruments on NOAA Polar Orbiting Environmental Satellites have been essential for global atmospheric monitoring, measuring radiation across various atmospheric levels The TOVS Path-B dataset offers atmospheric temperature and water vapor profiles, along with cloud and surface properties, at a spatial resolution of 1° latitude x 1° longitude, with 8 years of data (1987-1995) currently available at LMD The high spectral resolution of IR vertical sounders aids in identifying cirrus clouds both day and night Utilizing CO2 absorption band radiances, cloud-top pressure and effective IR cloud emissivity are calculated using a weighted c2 method Additionally, mean effective ice crystal sizes (De) and ice water path (IWP) for semi-transparent cirrus clouds are derived from spectral emissivity differences between 11 and 8 mm, sensitive to sizes up to 80 mm This cirrus dataset, covering NOAA-10 observations from 1987 to 1991, was developed as part of the European CIRAMOSA project.
The AVHRR instrument on NOAA satellites, featuring a spatial resolution of 1 km, has been utilized to examine the temporal changes in ice and water cloud parameters across Europe over a twelve-year span from 1990 to 2001 This analysis employs the AVHRR Processing scheme Over Land, Clouds, and Ocean (APOLLO).