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Projekt Druckansicht

Chemical and microphysical properties of natural cirrus and contrail cirrus

Fachliche Zuordnung Physik und Chemie der Atmosphäre
Förderung Förderung von 2009 bis 2011
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 111635694
 
Erstellungsjahr 2014

Zusammenfassung der Projektergebnisse

Cirrus clouds strongly affect the Earth´s climate, still the radiative forcing from natural cirrus and contrail cirrus depends on multiple parameters which are poorly constrained by observations. In this project we further develop instruments (FSSP, CIP, chemical ionization mass spectrometer AIMS) and perform aircraft measurements of ice crystal properties and of the HNO 3 partitioning in contrails and cirrus clouds. As the scientific operation of the HALO aircraft was delayed due to certification issues, we we pursued the opportunity to measure on other airborne platforms. Results within this project were achieved on the Falcon research aircraft during the CONCERT campaigns 2008 and 2011 and the Geophysica aircraft during the AMMA campaign. We address the following questions: (1) What is the size and shape of ice crystals in young contrails? And can we quantify their effect on climate in terms of radiative forcing? - Probability density functions of the size and the extinctions from young contrails were derived and their climate impact was estimated. Ashperical particles dominate the size distribution in >2min old contrails. (2) Has the aircraft type an impact on contrail properties? - For the first time we measure the impact of the aircraft type on contrail properties. Larger aircraft produce optically thicker contrails, normalized by passenger-seat-kilometer, larger aircraft are less climateactive. (3) Is there a difference in the nitric acid content in natural cirrus and contrails? Does trapping of nitric acid in cirrus ice crystals depend on ambient HNO3 concentrations? Can we quantify nitric acid concentrations and mixing in the tropopause region? - The nitric acid content in contrails is twice as high as in natural cirrus clouds. Nitric acid concentrations in the tropopause region depend on source, transport and mixing and influence trapping of HNO3 in ice crystals. (4) How do microphysical properties from cirrus formed in convective outflow develop during cirrus lifetime? - The changes of the size distributions of glaciated hydrometeors in the outflow of large meso-scale convective systems can be quantified as function of potential temperature and time in a way useful for modelling purposes. (5) Are deep convective clouds a source of ultrafine aerosol particles? - Yes, in high reaching tropical cumulonimbus clouds significant new particle formation can occur as was documentd from in-situ data. This may be a major source for new aerosol particles at the tropical gateway to the stratosphere. Scientific results from this project on micropyhsics and climate impact from contrails and natural cirrus clouds were published in scientific journals. In addition, results were reported in print media and TV and helped to advise aviation authorities, stakeholders and the public to take measures for a future sustainable airtraffic.

Projektbezogene Publikationen (Auswahl)

 
 

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