Numerical simulations of homogeneous freezing processes in the aerosol chamber AIDA
| Autor: | Olaf Stetzer, Ulrich Schurath, S. Schaefers, Cornelius Schiller, Ottmar Möhler, Bernd Kärcher, W. Haag, Martina Krämer |
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| Přispěvatelé: | Deutsches Zentrum für Luft- und Raumfahrt (DLR), Forschungszentrum Karlsruhe (FZK), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association |
| Jazyk: | angličtina |
| Rok vydání: | 2003 |
| Předmět: |
Atmospheric Science
010504 meteorology & atmospheric sciences Atmospheric sciences 01 natural sciences cirrus clouds lcsh:Chemistry Phase (matter) 0103 physical sciences Mixing ratio ddc:550 Relative humidity ice phase Supercooling 0105 earth and related environmental sciences [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere 010304 chemical physics Ice crystals Chemistry lcsh:QC1-999 Aerosol Deposition (aerosol physics) lcsh:QD1-999 13. Climate action Cirrus lcsh:Physics aerosols |
| Zdroj: | Atmospheric Chemistry and Physics Atmospheric Chemistry and Physics, European Geosciences Union, 2003, 3 (1), pp.195-210 Atmospheric chemistry and physics / Discussions 2, 1467-1508 (2002). Atmospheric Chemistry and Physics Discussions Atmospheric Chemistry and Physics Discussions, European Geosciences Union, 2002, 2 (5), pp.1467-1508 Atmospheric Chemistry and Physics, Vol 3, Iss 1, Pp 195-210 (2003) ResearcherID Atmospheric chemistry and physics 3, 195-210 (2003). |
| ISSN: | 1680-7316 1680-7324 1680-7367 1680-7375 |
| Popis: | International audience; The homogeneous freezing of supercooled H2SO4/H2O aerosols in an aerosol chamber is investigated with a microphysical box model using the activity parameterization of the nucleation rate by Koop et al (2000). The simulations are constrained by measurements of pressure, temperature, total water mixing ratio, and the initial aerosol size distribution, described in a companion paper Möhler et al. (2002). Model results are compared to measurements conducted in the temperature range between 194 and 235 K, with cooling rates in the range between 0.5 and 2.6 K min-1, and at air pressures between 170 and 1000 hPa. The simulations focus on the time history of relative humidity with respect to ice, aerosol size distribution, partitioning of water between gas and particle phase, onset times of freezing, freezing threshold relative humidities, aerosol chemical composition at the onset of freezing, and the number of nucleated ice crystals. The latter three parameters can directly be inferred from the experiments, the former three aid in interpreting the measurements. Sensitivity studies are carried out to address the relative importance of uncertainties of basic quantities such as temperature, H2O mixing ratio, aerosol size spectrum, and deposition coefficient of H2O molecules on ice. The ability of the numerical simulations to provide detailed explanations of the observations greatly increases confidence in attempts to model this process under real atmospheric conditions, for instance with regard to the formation of cirrus clouds or type-II polar stratospheric clouds, provided that accurate temperature and humidity measurements are available. |
| Databáze: | OpenAIRE |
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