Investigation of ice particle and cloud drop residues using the counterflow virtual impactor technique onboard HALO (HALO-CVI)
Zusammenfassung der Projektergebnisse
The most scientific improvements concerning ML-CIRRUS is the detection of two different size modes in the residual number size distribution inside contrail cirrus, which implies two different ice formation pathways, where also aircraft emitted particles seemed to be involved. Furthermore, it is very important for future cirrus studies that it worked out to identify and differentiate in-situ and liquid-phase originating cirrus clouds by the determination of the chemical signature of the IPR. With regard to ACRIDICON, the most scientific improvement are, that a higher number fraction of BC particles as CDR was measured in the lower part of deep convective clouds above a polluted compared to a rather clean boundary layer. The observation of young organic residual particles in the glaciated part of these clouds is a totally unexpected result and still requires a convincing explanation. The mean charge of drops was the first time measured in these kind of tropical deep convective clouds and indicated a rather fixed vertical behavior with large negative charges near cloud base and a transition to positive charges clearly below the 0°C height, which was at about 5000 m. This finding might help to improve our theoretical understanding about cloud electrification. A first surprise was the huge time delay in the determination of certification criteria for the HALO inlets, which led to an unexpected increase of development costs, which were jointly financed by DFG and TROPOS and which led to an unexpected course of the project. This disadvantage was partly compensated by the operation of HALO-CVI components in ground-based field campaigns, which yielded results that are part of corresponding publications. The second surprise was the much larger enhancement of cloud particles at the HALO-CVI inlet location as expected from particle trajectory calculations given in the HALO technical notes. This complicates the quantitative specification of residual particle number and mass at different flight levels, but relative numbers like number or mass fractions or mass per particle are still important parameters, which are derived from the HALO-CVI measurements. In addition, the certainty that the HALO-CVI inlet is located in the shadow zone for large ice particles is of great value, since this prevents ice fragmentation at least at the inlet and thus artefact sampling. Nevertheless, a HALO-CVI inlet installation position at the bottom fuselage or at the side of the cabin (window) would be of advantage for the quantitative and altitude independent sampling but it is not clear if this is technical feasible and affordable. The biggest surprises concerning the results are definitely the observation of young organic IPR in the anvil and of the drop charge vertical profiles in the lower part of the tropical deep convective clouds examined during ACRIDICON. Since ML-CIRRUS and ACRIDICON were one of the first HALO missions at all and especially the first two cloud missions, there were many reports in the public media, like TV and radio news broadcasts or daily newspapers. But this was always aiming as the missions as a whole without reporting on the results of individual measurements.
Projektbezogene Publikationen (Auswahl)
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(2012), In situ, airborne instrumentation: Addressing and solving measurement problems in ice clouds, Bull. Amer. Meteor. Soc., 93(2), ES29-ES34
Baumgardner, D., L. Avallone, A. Bansemer, S. Borrmann, P. Brown, U. Bundke, P. Y. Chuang, D. Cziczo, P. Field, M. Gallagher, J.-F. Gayet, A. Heymsfield, A. Korolev, M. Krämer, G. McFarquhar, S. Mertes, O. Möhler, S. Lance, P. Lawson, M. Petters, K. Pratt, G. Roberts, D. Rogers, O. Stetzer, J. Stith, W. Strapp, C. Twohy, and M. Wendisch
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(2013), Enhanced role of transition metal ion catalysis during in-cloud oxidation of SO2, Science, 340(6133), 727-730
Harris, E., B. Sinha, D. van Pinxteren, A. Tilgner, W. Fomba, J. Schneider, A. Roth, T. Gnauk, B. Fahlbusch, S. Mertes, T. Lee, J. Collett, S. Foley, S. Borrmann, P. Hoppe, and H. Herrmann
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(2014), Assessment of cloud supersaturation by size-resolved aerosol particle and cloud condensation nuclei (CCN) measurements, Atmos. Meas. Tech. (AMT), 7, 2615-2629
Krüger, M. L., S. Mertes, T. Klimach, Y. F. Cheng, H. Su, J. Schneider, M. O. Andreae, U. Pöschl, and D. Rose
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(2014), Do cloud properties in a Puerto Rican tropical montane cloud forest depend on occurrence of long-range transported African dust?, Pure Appl. Geophys.
Spiegel, J. K., N. Buchmann, O. L. Mayol-Bracero, L. A. Cuadra Rodríguez, C. J. Valle Díaz, K. A. Prather, S. Mertes, and W. Eugster
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(2015), Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques, Atmos. Chem. Phys., 15, 4161-4178
Worringen, A., K. Kandler, N. Benker, T. Dirsch, S. Mertes, L. Schenk, U. Kästner, F. Frank, B. Nillius, U. Bundke, D. Rose, J. Curtius, P. Kupiszewski, E. Weingartner, P. Vochezer, J. Schneider, S. Schmidt, S. Weinbruch, and M. Ebert
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(2015), The Ice Selective Inlet: a novel technique for exclusive extraction of pristine ice crystals in mixed-phase clouds, Atmos. Meas. Tech. (AMT), 8, 3087-3106
Kupiszewski, P., E. Weingartner, P. Vochezer, M. Schnaiter, A. Bigi, M. Gysel, B. Rosati, E. Toprak, S. Mertes, and U. Baltensperger
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(2016), Aerosol properties, source identification, and cloud processing in orographic clouds measured by single particle mass spectrometry on a Central European mountain site during HCCT-2010, Atmos. Chem. Phys., 16, 505-524
Roth, A., J. Schneider, T. Klimach, S. Mertes, D. van Pinxteren, H. Herrmann, and S. Borrmann
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(2016), Cloud water composition during HCCT-2010: Scavenging efficiencies, solute concentrations, and droplet size dependence of inorganic ions and dissolved organic carbon, Atmos. Chem. Phys., 16, 3185–3205
van Pinxteren, D., K. W. Fomba, S. Mertes, K. Müller, G. Spindler, J. Schneider, T. Lee, J. L. Collett, and H. Herrmann
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(2016), Introduction of the ACRIDICON–CHUVA campaign studying tropical deep convective clouds and precipitation over Amazonia using the new German research aircraft HALO, Bull. Amer. Meteor. Soc.
Wendisch, M., ..., S. Mertes, ... M. Zöger
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(2016), ML-CIRRUS - The airborne experiment on natural cirrus and contrail cirrus with the high-altitude long-range research aircraft HALO, Bull. Amer. Meteor. Soc.
Voigt, C., ..., S. Mertes, ... M. Zöger
