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www.atmos-meas-tech-discuss.net/4/6845/2011/
doi:10.5194/amtd-4-6845-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Atmospheric ice nucleators active ≥−12°C may be quantified on PM10 filters
1Institute of Environmental Geosciences, University of Basel, 4056 Basel, Switzerland
2Empa, Swiss Federal Laboratories for Materials Science and Technology, Duebendorf, Switzerland
3INRA, Unité de Pathologie Végétale UR407, 84140 Montfavet, France
Abstract. Small number concentrations render it difficult to quantify ice nucleators (IN) active at warm temperatures. An improved filter method is proposed. It makes use of quartz filters which had been used in 24 h PM10 monitoring (720 m3 air sample). Small subsamples (1.8 mm diameter) from the effective filter area and from the clean fringe (blank) are subjected to immersion freezing tests. We applied the method to eight filters from the High Alpine Research Station Jungfraujoch (3580 m a.s.l.) in the Swiss Alps. All filters carried IN active at −7 °C and below. Number concentrations of IN active at −8, −10, and −12 °C were on average 3.3, 10.7, and 17.2 m−3, respectively. Severalfold larger numbers of IN active at ≥−12 °C per unit mass of PM10 were found in air masses influenced by Swiss and Southern German atmospheric boundary layer air, compared to a Saharan dust event. In combination with data on PM10 mass and atmospheric transport simulations, the method may be used to re-construct time series of IN number concentrations.
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Notice on Discussion StatusCitation: Conen, F., Henne, S., Morris, C. E., and Alewell, C.: Atmospheric ice nucleators active ≥−12°C may be quantified on PM10 filters, Atmos. Meas. Tech. Discuss., 4, 6845-6860, doi:10.5194/amtd-4-6845-2011, 2011. Bibtex EndNote Reference Manager XML
