 |
| Titel |
Model calculations for the airborne Fast Ice Nuclei CHamber FINCH-HALO |
| VerfasserIn |
B. Nillius, H. Bingemer, U. Bundke, R. Jaenicke, B. Reimann, T. Wetter |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250023503
|
|
|
|
|
|
| Zusammenfassung |
| Ice nuclei (IN) initiate the formation of primary ice in tropospheric clouds. In mixed phase clouds the primary ice crystals can grow very fast by the Bergeron-Findeisen process (Findeisen, 1938) at the expense of evaporating water droplets, and form precipitation. Thus, IN are essential for the development of precipitation in mixed phase clouds in the middle latitude. However, the role of IN in the development of clouds is still poorly understood and needs to be studied (Levin and Cotton, 2007).
A Fast Ice Nuclei CHamber (FINCH-HALO) for airborne operation on the High And LOng Range research aircraft (HALO) is under development at the Institute for Atmosphere and Environment University Frankfurt. IN particles are activated within the chamber at certain ice super-saturation and temperature by mixing three gas flows, a warm moist, a cold dry, and an aerosol flow. After activation the particles will grow within a processing chamber. In an optical depolarisation detector droplets and ice crystals are detected separately.
The setup of the new FINCH-HALO instrument is based on the ground based IN counter FINCH (Bundke, 2008).
In FINCH-HALO a new cooling unit is used. Thus, measurements down to -40°C are possible. Furthermore minor changes of the inlet section where the mixing occurs were done.
The contribution will present 3D model calculations with FLUENT of the flow conditions in the new inlet section for different pressure levels during a flight typical for HALO. Growth rates of ice crystals in the chamber at different temperature and super-saturation will be shown.
References:
Bundke U., B. Nillius, R. Jaenicke, T. Wetter, H. Klein, H. Bingemer, (2008).
The Fast Ice Nucleus Chamber FINCH,
Atmospheric Research, doi:10.1016/j.atmosres.2008.02.008
Findeisen, R., (1938).
Meteorologisch-physikalische Begebenheiten der Vereisung in der Atmosphäre.
Hauptversammlung 1938 der Lilienthal-Gesellschaft.
Levin, Z., W. Cotton, (2007).
Aerosol pollution impact on precipitation: a scientific review.
The WMO/IUGG International Aerosol Precipitation Science Assessment Group (IAPSAG).
World Meteorological Organization, Geneva.
Acknowledgements:
This work was supported by the German Research Foundation, SFB 641 “Tropospheric Ice Phase” TP A1, SPP 1294, BU 1432/3-1, JA 344/12-1, by the Helmholtz Association, VI-233 “Aerosol Cloud Interactions” and by the EU FP6 Infrastructure Project EUSAAR. |
|
|
|
|
|
|