Contrails - Research, comments and links

Contrails and Aviation-cirrus 
Aerosols  (01)


U. S. Flight Track Database

This flight track work is part of a larger effort to understand the effects of contrail derived anthropogenic cirrus clouds on global climate. For more information please refer to the NASA Langley Cloud and Radiation Research page of Dr. Patrick Minnis.
Source: http://www-pm.larc.nasa.gov/


Modeling of Soot Precursor Formation in Laminar Premixed Flames with 
C1-, C2- and C6-Fuels (AAC 2003)

Goos, Elke(1); Braun-Unkhoff, Marina(1); Slavinskaya, Nadezhda; Frank, Peter(1)
(1) Institut für Verbrennungstechnik, DLR.-Stuttgart, Germany;
contact: elke.goos@dlr.de

Aromatics and polycyclic aromatic hydrocarbons (PAH) are of particular concern in combustion processes because of their potentially adverse health effects. They are formed in the combustion of hydrocarbon fuels (e.g. kerosene) and have been identified as key precursors of soot.

Former investigations of flame and shock tube experiments, especially at high pressures, show the importance of the PAH growth on soot particle inception and on calculated soot volume fraction. [..]


Modelling of volatile particles during PartEmis  (AAC 2003)

Vancassel, Xavier(1); Sorokin,Andrey(2); Mirabel,Philippe(1)
(1) Université Louis Pasteur Strasbourg, France; (2) Central Institute of Aviation Motors, Moscow, Russia.
contact: mirabel@illite.u-strasbg.fr

In the frame of the European project PartEmis, volatile particles produced in the sampling system of a combustor test rig has been modelled. These particles, although formed in situations which differ from those prevailing during flight conditions, remain of major interest as their growth is highly connected to the amount of sulphuric acid available in the exhaust. In this matter, attention has been paid to the sulphur conversion factor required to fit the modelled results to the measurements of volatile particles, in the 4 to 7 nm size range. [..]

As a conclusion, the modelling of particle formation in the sulphuric acid-water binary system has provided an indirect way to estimate an upper limit of sulphur conversion, one of the key parameters needed to understand particle formation and evolution in an aircraft plume.


Growing and Dispersion of Particles in a Turbulent Exhaust Plume

Garnier, François(1); Ferreira-Gago, Cécile; Brasseur, Anne-Lise; Uthéza, Françoise(2), Paoli, Roberto(3), Cuenot, Benedicte
(1) ONERA - DMPH, Unité Environnement Atmospherique et Givrage, Chatillon, France; (2) Université de Marne-la-Vallée, LETEM, Marne-la-Vallée, France; (3) CERFACS, Toulouse, France
contact: francois.garnier@onera.fr

Emissions of water vapor, sulfur dioxide and particles (soot, metallic particles…) by jet engine is known to induce the formation of new particles , i;e; aerosols and contrails. These particles may have an impact on cloudiness and may affect the Earth’s radiative budget balance. In order to better understand their formation, preliminary studies on the dispersion of particles (soot and aerosols) in the exhaust jet and on their modification by plume processing are necessary.

This work is focused on the numerical simulation of dynamics and growth of spherical particles in the near-field of an aircraft wake. [..]


Atmospheric Physics Branch

Cloud-Aerosol Interactions

Atmospheric Physics Branch / Earth Science Division

Both aerosol and cloud particles play significant roles in regulating the earth's energy balance. Clouds can act as both sinks and sources of aerosol particles. We discovered that tropical cirrus are a significant source of aerosols when we determined the particle size spectrum between 20 nm and 2.4 mm in the outflow portion of a convective tropical cloud with a multiinstrument approach involving condensation nuclei counter, Ames wire impactors and replicators, and optical particle counters1. Results suggest the following mechanism of aerosol formation: Small particles, dubbed cirrus haze, are formed by the condensation of water vapor on hygroscopic nuclei. These nuclei may originate in the ocean, result from volcanic eruptions, or be generated photolytically in situ.

1Pueschel, R.F., et al., Aerosol and cloud particles in tropical cirrus anvil: Importance to radiation balance. J. Aerosol Sci.28, 1123-1136, 1997.

Research Staff
Rudolf F. Pueschel
Anthony W. Strawa
Guy V. Ferry

Point of Contact
Rudolf F. Pueschel, (650) 604-5254
rpueschel@mail.arc.nasa.gov

Collaborators
Jindra Goodman, San Jose State University
John Hallett, Desert Research Institute
Steve Howard, Symtech
Sunita Verma, SSAI


Aerosol from aircraft can affect the environment in three ways: First, soot aerosol has been implicated to cause long-term ozone depletion at mid-latitudes in the lower stratosphere at a rate of approximately 5% per decade1. This effect is in addition and unrelated to the polar ozone holes which are strongly influenced by heterogeneous chemistry on polar stratospheric clouds. Second, the most obvious effect of jet aircraft is the formation of visible contrails in the upper troposphere. The Salt Lake City region experienced an 8% increase in cirrus cloud cover over a 15-year period2 which covariates with an increase in regional commercial air traffic. If soot particles act as freezing nuclei to cause contrail formation3 heterogeneously, they would be linked to a secondary effect to cloud modification that very likely is climatologically important. Third, a buildup of soot aerosol could reduce the single scatter albedo of stratospheric aerosol from 0.993±0.004 to 0.98, a critical value4 that separates stratospheric cooling from warming.

Thus arises an important question: Do aircraft emit sufficient amounts of soot to have detrimental effects and warrant emission controls?

Research Staff
Rudolf F. Pueschel
Anthony W. Strawa
Guy V. Ferry


Russell.Aerosols.html

AEROSOLS AND THEIR RADIATIVE/CLIMATIC EFFECTS: SPACE, AIR, AND GROUND MEASUREMENTS AND ANALYSES

Philip B. Russell and Rudolf F. Pueschel1

As a part of Science Team activities for the spacecraft sensors SAM II, Stratospheric Aerosol and Gas Experiment (SAGE, SAGE II, and SAGE III), Ames has designed, participated in, and analyzed measurements by aircraft, balloons, and ground-based remote sensors to validate and complement the spacecraft measurements. Current and recent activities include ER-2 and DC-8 campaigns to measure particle size distribution, composition, and optical depth spectra before and after the Pinatubo eruption (in coordination with SAGE II measurements), developing the data validation plan for the SAGE III sensor (to fly on the Earth Observing System, EOS), and designing several autotracking sunphotometers to fly on a variety of occupied and unoccupied aerial vehicles (UAVs) as a component of multidisciplinary studies of aerosol climatic effects.


Contrails can evolve into extended cirrus clouds. Boucher (1999) and Fahey et al. (1999) have shown evidences that cirrus occurrence and coverage may have increased in regions of high air traffic compared with the rest of the globe. Smith et al. (1998) reported the existence of nearly invisible layers of small ice crystals, which cause absorption of infrared radiation, and could be due to remnant contrail particles. From consideration of the spatial distribution of cirrus trends during the last 25 years, Fahey et al. (1999) gave a range of possible best estimates of 0 to 0.04 Wm-2 for the radiative forcing due to aviation-induced cirrus. The available information on cirrus clouds was deemed insufficient to determine a single best estimate or an uncertainty range
[...]
Aerosols also serve as ice nuclei although it is well recognised that there are fewer ice nuclei than cloud condensation nuclei. It is conceivable that anthropogenic aerosols emitted at the surface and transported to the upper troposphere affect the formation and properties of ice clouds. Jensen and Toon (1997) suggested that insoluble particles from the surface or soot particles emitted by aircraft, if they serve as effective ice nuclei, can result in an increase in the cirrus cloud coverage. Laaksonen et al. (1997) argued that nitric acid pollution is able to cause an increase in supercooled cirrus cloud droplet concentrations, and thereby influence climate. Such effects, if significant at all, are not quantified at present..
(Source: ipcc.ch/pub/tar/wg1/242.htm is no longer available)


European Workshop on Aviation, Aerosols, Contrails and Cirrus Clouds

New homepage address of IPA Institut für Physik der Atmosphäre
Neue Adresse der Homepage Seit 1. Oktober 2002 finden Sie die WWW-Seiten unseres Instituts unter der neuen Adresse:
www.dlr.de/ipa Bitte ändern Sie ihre Bookmarks entsprechend ab. Vielen Dank.
Institute of Atmospheric Physics
New Address Our homepage has moved. Our new address:
www.dlr.de/ipa Please correct your bookmarks. Thank you.

This focussed Workshop will address persisting uncertainties on the role of aerosols and particles from aviation and other sources to contrails and cloud formation with impact on stratospheric ozone and climate. The recent European and international assessments (WMO, IPCC, ICAO) stress the urgent need to clarify these uncertainties, which limit our ability to project the atmospheric impacts of aviation. The workshop will provide a forum for presentation of the results of current and past EC and national research activities in this field (including THESEO). The outcome of the Workshop will contribute to the regulatory process within ICAO and the Montreal Protocol. For aviation industry is also of great importance to know which type of aircraft emissions has the largest impact on contrails and cloud formation.
Further information: ulrich.schumann@dlr.de or georgios.amanatidis@cec.eu.int


Cynthia Twohy

http://raf.atd.ucar.edu/~cindy/index.html (no longer available)

Assistant Professor (Research)
College of Oceanography and Atmospheric Sciences
Oceanography Admin 104
Oregon State University
Corvallis, OR 97331-5503

Most of my OSU research is related to atmospheric aerosols and aerosol/cloud interactions, with an emphasis on airborne measurements. I also work on a project basis for the National Center for Atmospheric Research, coordinating the deployment of the counterflow virtual impactor (CVI) when it is requested for an airborne field program.

Refereed, journals:

Twohy, C.H., P. Austin and R.J. Charlson, 1989: Chemical consequences of the initial diffusional growth of cloud droplets: a clean marine case. Tellus, 41B, 51-60.

Twohy, C.H., A.D. Clarke, S.G. Warren, L.F. Radke and R.J. Charlson, 1989: Light-absorbing material extracted from cloud droplets and its effect on cloud albedo. J. Geophys. Res., 94, 8623-8631.

Twohy, C.H., and D. Rogers, 1993: Airflow and water drop trajectories at instrument sampling points around the Beechcraft King Air and Lockheed Electra. J. Atmos. Oceanic Technol., 10, 566-578.

Drdla, K., A. Tabazadeh, R.P. Turco, M.Z. Jacobson, J.E. Dye, C. Twohy and D. Baumgardner, 1994: Analysis of the physical state of one Arctic polar stratospheric cloud based on observations. Geophys. Res. Lett., 21, 2475-2478.

Twohy, C.H., P.A. Durkee, B.J. Huebert and R.J. Charlson, 1995: Effects of aerosol particles on the microphysics of coastal stratiform clouds. J. Climate, 8, 773-783.

Twohy, C.H., and J.G. Hudson, 1995: Measurements of cloud condensation nucleus spectra within maritime cumulus cloud droplets: Implications for mixing processes. J. Appl. Meteor., 34, 815-833.

Twohy, C.H., Schanot, A.J. and W.A. Cooper, 1997: Measurement of condensed water content in liquid and ice clouds using an airborne counterflow virtual impactor. J. Atmos. Oceanic Tech., 14, 197-202.

Jensen, E. J., O. B. Toon, S. Kinne, G. W. Sachse, B. E. Anderson, K. R. Chan, C. H. Twohy, B. Gandrud, A. J. Heymsfield, and R. C. Miake-Lye, 1998: Environmental conditions required for contrail formation and persistence. J. Geophys. Res., 103, 3929-3936.

Jensen, E.J., O.B. Toon, A. Tabazadeh, G.W. Sachse, B.E. Anderson, K.R. Chan, C. Twohy, B. Gandrud, S.M. Aulenbach, A. Heymsfield, J. Hallett, and B. Gary, 1998: Ice nucleation processes in upper tropospheric wave-clouds observed during SUCCESS. Geophys. Res. Lett., 25, 1363-1366.

Laucks, M.L., and C. H. Twohy, 1998: Size-dependent sampling efficiency of an airborne counterflow virtual impactor. Aer. Sci. and Tech., 28, 40-61.

Twohy, C.H., 1998: Model calculations and wind tunnel testing of an isokinetic shroud for high-speed sampling. Aer. Sci. and Tech., 28, 261-280.

Twohy, C. H., and B. Gandrud, 1998: Electron microscope analysis of residual particles from aircraft contrails. Geophys. Res. Lett., 25, 1359-1362.

Vay, S., B.E. Anderson, G.W. Sachse, J.E. Collins, J.R. Podolske, C.H. Twohy, B. Gandrud, K. R. Chan, S.L. Baughcum, and H.A. Wallio, 1998: DC-8-based observations of aircraft CO, CH4, N2O, and H2O emission indices during SUCCESS. Geophys. Res. Lett., 25, 1717-1720.

Weinheimer, A.J., T.L. Campos, J.G. Walega, F.E. Grahek, B.A. Ridley, D. Baumgardner, C. H. Twohy, and B. Gandrud, and E.J. Jensen 1998: Uptake of NOy on wave-cloud ice particles. Geophys. Res. Lett., 25, 1725-1728.

Refereed, other:

Charlson, R.J., C.H. Twohy and P.K. Quinn, 1988: Physical influences of altitude on the chemical properties of clouds and of water deposited from the troposphere. In Acid Deposition at High Altitude Sites. M.H. Unsworth and D. Fowler (eds.), Kluwer Academic Publishers.

Internally refereed:

Twohy, C.H., 1991: Airborne Condensation Nucleus Counter User's Guide. Technical Note TN-356+EDD, National Center for Atmospheric Research, 21 pp.

Twohy, C.H., and D. Rogers, 1991: Flow speed and particle trajectories around aircraft: theory and measurements. In Technical Note TN-362+1A, National Center for Atmospheric Research, 15 pp.

Non-refereed:

Twohy, C.H., A.D. Clarke, S.G. Warren, L.F. Radke and R.J. Charlson, 1989: Measurements of the light-absorbing material inside cloud droplets and its effect on cloud albedo. Symposium on the role of clouds in atmospheric chemistry and global climate, Anaheim, American Meteorological Society, 215-220.

Twohy, C.H., B.J. Huebert, P.A. Durkee and R.J. Charlson, 1990: Droplet chemistry in stratocumulus clouds. Conference on Cloud Physics, San Francisco, American Meteorological Society, 527-531.

Baumgardner, D., and C. Twohy, 1991: Conditional sampling of aerosol and cloud droplets in continental and marine air masses, XX General Assembly of the IUGG, Vienna, Austria, 32.

Twohy, C.H., and D. Rogers, 1991: Airflow effects on the distribution of water droplets around an aircraft. Seventh Symposium on Meteorological Observations and Instrumentation, New Orleans, American Meteorological Society, 256-260.

Twohy, C.H., P.A. Durkee, K. Nielsen and R.J. Charlson, 1991: Relationships between aerosol particles, droplets, and satellite-measured reflectance in coastal stratiform clouds. XX General Assembly of the IUGG, Vienna, Austria, 50.

Dye, J.E., D. Baumgardner, S. Borrmann, C. Twohy, K. Drdla, and P. Newman, 1992: Stratospheric sulfate droplets and transition to polar stratospheric cloud particles. presented at AGU Fall Meeting, San Francisco, American Geophysical Union.

Twohy, C.H., and T.L. Anderson, 1992: Sampling artifacts produced in aircraft aerosol inlets by the presence of large cloud droplets. Eleventh Annual Meeting, San Francisco, American Association for Aerosol Research, 300.

Twohy, C.H., P.A. Durkee and R.J. Charlson, 1992: Effects of aerosol particles on droplet size distributions and satellite-measured reflectance in coastal stratiform clouds, Abstracts, Eleventh Annual Meeting, San Francisco, American Association for Aerosol Research, 307.

Anderson, T.L., and C.H. Twohy, 1993: Collection and exclusion of large cloud elements with a counterflow virtual impactor. Twelfth Annual Meeting, Oak Brook, Illinois, American Association for Aerosol Research, 36.

Radke, L.R., and C.H. Twohy, 1993: Aerosol particle production near the atmosphere's clouds interface: sorting fact from artifact. AGU Fall Meeting, San Francisco, California (5-10 Dec 1993), American Geophysical Union, 174.

Radke, L.R., B.W. Gandrud, J.E. Ragni, C.H. Twohy and D. Baumgardner, 1994: Aircraft research platforms with stratospheric capability. Proc. First Intl. Airborne Remote Sensing Conference and Exhibition, Strasbourg, France (11-15 Sept 1994), Environmental Research Institute of Michigan, I281-I293.

Twohy, C.H., 1994: Measurement of condensed water content in clouds using an airborne counterflow virtual impactor.Proc. Conference on Aerosols and Atmospheric Optics, Snowbird, Utah (26-30 Sept 1994), American Geophysical Union., 534.

Twohy, C.H., A.J. Schanot, M.L. Laucks, T.L. Anderson, and R.J. Charlson, 1994: Measurement of ice cloud properties using an airborne counterflow virtual impactor. Fourth International Aerosol Conference, Los Angeles, California (29 Aug-2 Sept 1994), American Association for Aerosol Research, 1045.

Twohy, C.H., 1995: Precipitation. In Gale Encyclopedia of Science, Gale Research, Detroit.

Laucks, M.L., and C. H. Twohy, 1996: Size-dependent sampling efficiency of an airborne counterflow virtual impactor. Fifteenth Annual Conference, Orlando (14-18 Oct 1996), American Association for Aerosol Research, 233.

Litchy, M.L., S.G. Howell, A.D. Clarke, B.J. Huebert, D. Baumgardner, D. Rogers, and C. H. Twohy, 1996: Measurements of the passing efficiency of the community aerosol inlet and associated tubing on NCAR's C-130 aircraft. Fifteenth Annual Conference, Orlando (14-18 Oct 1996), American Association for Aerosol Research, 20.

Twohy, C.H., 1996: Model calculations and wind tunnel testing of a shroud for an airborne counterflow virtual impactor. Fifteenth Annual Conference, Orlando (14-18 Oct 1996), American Association for Aerosol Research, 232.

Faloona, I., D. Tan, W. Brune, C. Twohy, and B. Gandrud, 1997: Measurements of OH/HO2 in and around cirrus clouds. AGU Spring Meeting, Baltimore, Maryland (27-30 May 1997), American Geophysical Union, S86 (EOS supplement).

Jensen, E.J., O.B. Toon, A. Tabazadeh, G.W. Sachse, B.E. Anderson, K.R. Chan, C. Twohy, and B. Gandrud, 1997, Ice nucleation processes in upper tropospheric wave-clouds observed during SUCCESS. AGU Spring Meeting, Baltimore, Maryland (27-30 May 1997), American Geophysical Union, S94 (EOS supplement).

Twohy, C. H., B.W. Gandrud, A.J. Heymsfield, D. Baumgardner, C. Buettner, H. Gerber, P. DeMott, and K R. Chan, 1997: Measurements of contrail nuclei and cirrus cloud microphysics. Invited paper. AGU Spring Meeting, Baltimore, Maryland (27-30 May 1997), American Geophysical Union, S97 (EOS supplement).

Internet: twohy@oce.orst.edu
Phone: (541) 737-5690 or (503) 472-0528
Fax: (541) 737-2540

Go to: Oregon State University's College of Oceanography and Atmospheric Sciences

Go to: NCAR's Research Aviation Facility


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