References

ACPD

Atmospheric Chemistry and Physics Discussions

ACPD

1680-7375

Copernicus GmbH

Göttingen, Germany

10.5194/acpd-9-463-2009

Studies of heterogeneous freezing by three different desert dust samples

Connolly

P. J.

¹ Möhler

² Field

P. R.

³ Saathoff

² Burgess

¹ Choularton

¹ Gallagher

School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, UK

IMK-AAF Forschungszentrum Karlsruhe, Germany

Met Office, Exeter, UK

08 01 2009

9 1 463 514

This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

This article is available from http://www.atmos-chem-phys-discuss.net/9/463/2009/acpd-9-463-2009.html

The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/9/463/2009/acpd-9-463-2009.pdf

We present results of experiments at the aerosol interactions and dynamics in the atmosphere (AIDA) chamber facility looking at the freezing of water by three different types of mineral particles at temperatures between −12°C and −33°C. The three different dusts are Asia Dust-1 (AD1), Sahara Dust-2 (SD2) and Arizona test Dust (ATD). The dust samples used had particle concentrations of sizes that were log-normally distributed with mode diameters between 0.3 and 0.5 μm and standard deviations, σg, of 1.6–1.9. The results from the freezing experiments are consistent with the singular hypothesis of ice nucleation. The dusts showed different nucleation abilities, with ATD showing a rather sharp increase in ice-active surface site density at temperatures less than −24°C. AD1 was the next most efficient freezing nuclei and showed a more gradual increase in activity than the ATD sample. SD2 was the least active freezing nuclei. We used data taken with particle counting probes to derive the ice-active surface site density forming on the dust as a function of temperature for each of the three samples and polynomial curves are fitted to this data. The curve fits are then used independently within a bin microphysical model to simulate the ice formation rates from the experiments in order to test the validity of parameterising the data with smooth curves. Good agreement is found between the measurements and the model for AD1 and SD2; however, the curve for ATD does not yield results that agree well with the observations. The reason for this is that more experiments between −20 and −24°C are needed to quantify the rather sharp increase in ice-active surface site density on ATD in this temperature regime. The curves presented can be used as parameterisations in atmospheric cloud models where cooling rates of approximately 1°C min−1 or more are present to predict the concentration of ice crystals forming by the condensation-freezing mode of ice nucleation. Finally a polynomial is fitted to all three samples together in order to have a parameterisation describing the average ice-active surface site density vs. temperature for an equal mixture of the three dust samples.

References 1

Ansmann,~A., Tesche,~M., Althausen,~D., Müller,~D., Seifert,~P., Freudenthaler,~V., Heese,~B., Wiegner,~M., Pisani,~G., Knippertz,~P., and Dubovik,~O.: Influence of Saharan dust on cloud glaciation in southern Morocco during the Saharan Mineral Dust Experiment, J. Geophys. Res., 113, D04210, doi:10.1029/2007JD008785, 2008.

Archuleta, C. M., DeMott, P. J., and Kreidenweis, S. M.: Ice nucleation by surrogates for atmospheric mineral dust and mineral dust/sulfate particles at cirrus temperatures, Atmos. Chem. Phys., 5, 2617–2634, 2005.

Bailey,~M. and Hallett,~J.: Growth rates and habits of ice crystals between $-20\unit\degree C$ and $-70\unit\degree C$, J. Atmos. Sci., 61, 514–544, 2004.

Connolly,~P J., Flynn,~M J., Ulanowski,~Z., Ibbottson,~T., Gallagher,~M W., and Choularton,~T W.: Calibration of the cloud particle imager probes using calibration beads and ice crystal analogs: the depth-of-field, J. Atmos. Ocean. Technol., 24, 1860–1879, 2007.

DeMott,~P J., Sassen,~K., Poellot,~M R., Baumgardner,~D., Rodgers,~D C., Brooks,~S D., Prenni,~A J., and Kreidenweis,~S M.: African dust aerosols as atmospheric ice nuclei, Geophys. Res. Lett., 30, 1732–1735, 2003.

Field, P. R., Möhler, O., Connolly, P., Krämer, M., Cotton, R., Heymsfield, A. J., Saathoff, H., and Schnaiter, M.: Some ice nucleation characteristics of Asian and Saharan desert dust, Atmos. Chem. Phys., 6, 2991–3006, 2006

Formenti,~P., Elbert,~W., Maenhaut,~W., Haywood,~J., and Andreae,~M.: Chemical composition of mineral dust aerosol during the Saharan Dust Experiment (SHADE) airborne campaign in the Cape Verde region, September 2000, J. Geophys. Res., 108 (D18), 8576, doi:10.1029/2002JD002648, 2003.

Hirst,~E., Kaye,~P H., Greenaway,~R S., Field,~P R., and Johnson,~D.: Discrimination of micrometer-sized ice and super-cooled droplets in mixed-phase cloud, Atmos. Environ., 35, 33–47, 2001.

Hobbs,~P V. and Rangno,~A L.: Ice particle concentrations in clouds, J. Atmos. Sci., 42, 2523–2549, 1985.

Hobbs,~P V. and Rangno,~A L.: Rapid development of high ice particle concentrations in small polar maritime cumuliform clouds, J. Atmos. Sci., 47, 2710–2722, 1990.

Krueger,~B J., Grassian,~V H., Cowib,~J P., and Laskin,~A.: Heterogeneous chemistry of individual mineral dust particles from different dust source regions: the importance of particle mineralogy, Atmos. Environ., 38, 6253–6261, 2004.

Lawson,~P., Baker,~B A., Schmitt,~C G., and Jensen,~T L.: An overview of microphysical properties of Artic clouds observed in May and July 1998 during FIRE ACE, J. Geophys. Res., 106, 14 989–15 014, 2001.

Linke, C., Möhler, O., Veres, A., Mohácsi, \'A., Bozóki, Z., Szabó, G., and Schnaiter, M.: Optical properties and mineralogical composition of different Saharan mineral dust samples: a laboratory study, Atmos. Chem. Phys., 6, 3315–3323, 2006.

McConnell, C. L., Highwood, E. J., Coe, H., Formenti, P., Anderson, B., Osborne, S., Nava, S., Desboeufs, K., Chen, G., and Harrison, M. A. J.: Seasonal variations of the physical and optical characteristics of Saharan dust: Results from the Dust Outflow and Deposition to the Ocean (DODO) experiment, J. Geophys. Res., 113, D14S05, doi:10.1029/2007JD009606, 2008.

Möhler,~O., Wagner,~R., Linke,~C., Schnaiter,~M., Saathoff,~H., Mangold,~A., Krämer,~M., Ebert,~V., Schutz,~L., Field,~P R., Connolly,~P J., and Heymsfield,~A J.: Formation, growth and habit of ice crystals nucleated on mineral dust aerosol, 14th ICCP, Bologna, Italy, 2004.

Möhler, O., Field, P. R., Connolly, P., Benz, S., Saathoff, H., Schnaiter, M., Wagner, R., Cotton, R., Krämer, M., Mangold, A., and Heymsfield, A. J.: Efficiency of the deposition mode ice nucleation on mineral dust particles, Atmos. Chem. Phys., 6, 3007–3021, 2006.

Murphy,~D M. and Koop,~T.: Review of the vapour pressures of ice and supercooled water for atmospheric applications, Quart. J. Roy. Meteorol. Soc., 131, 1539–1565, 2005.

Pruppacher,~H R. and Klett,~J D.: Microphysics of clouds and precipitation, \qutKluwer Academic Press, Norwell, 1997.

Sassen,~K., DeMott,~P J., Prospero,~J M., and Poellot,~M R.: Saharan dust storms and indirect aerosol effects on clouds: CRYSTAL-FACE results, Geophys. Res. Lett., 30, 1633–1636, 2003.

Topping, D. O., McFiggans, G. B., and Coe, H.: A curved multi-component aerosol hygroscopicity model framework: Part 1 – Inorganic compounds, Atmos. Chem. Phys., 5, 1205–1222, 2005a.

Topping, D. O., McFiggans, G. B., and Coe, H.: A curved multi-component aerosol hygroscopicity model framework: Part 2 – Including organic compounds, Atmos. Chem. Phys., 5, 1223–1242, 2005b.

Vali,~G.: Quantitative evaluation of experimental results on the heterogeneous freezing nucleation of supercooled liquids, J. Atmos. Sci., 28, 402–409, 1971.

Vali,~G.: Freezing rate due to heterogeneous nucleation, J. Atmos. Sci., 31, 1843–1856, 1994.