African dust aerosols as atmospheric ice nuclei

[1] Measurements of the ice nucleating ability of aerosol particles in air masses over Florida having sources from North Africa support the potential importance of dust aerosols for indirectly affecting cloud properties and climate. The concentrations of ice nuclei within dust layers at particle sizes below 1 μm exceeded 1 cm−3; the highest ever reported with our device at temperatures warmer than homogeneous freezing conditions. These measurements add to previous direct and indirect evidence of the ice nucleation efficiency of desert dust aerosols, but also confirm their contribution to ice nuclei populations at great distances from source regions.

[1]  D. Rogers,et al.  Concerning primary ice nuclei concentrations and water supersaturations in the atmosphere , 1994 .

[2]  D. Rosenfeld,et al.  Seeding effectiveness : The interaction of desert dust and the southern margins of rain cloud systems in Israel , 1996 .

[3]  H. Maring,et al.  Dust vertical distribution in the Caribbean during the Puerto Rico Dust Experiment , 2002 .

[4]  Kenneth Sassen,et al.  Indirect climate forcing over the western US from Asian dust storms , 2002 .

[5]  M. Molina,et al.  Heterogeneous nucleation of ice in (NH4)2SO4‐H2O particles with mineral dust immersions , 2002 .

[6]  Daniel Rosenfeld,et al.  Ice Nuclei, Rainwater Chemical Composition, and Static Cloud Seeding Effects in Israel , 1996 .

[7]  T. Carlson,et al.  The Large-Scale Movement of Saharan Air Outbreaks over the Northern Equatorial Atlantic , 1972 .

[8]  S. Kreidenweis,et al.  Measurements of ice nucleating aerosols during SUCCESS , 1998 .

[9]  S. Kreidenweis,et al.  A Continuous-Flow Diffusion Chamber for Airborne Measurements of Ice Nuclei , 2001 .

[10]  J. Prospero.  Saharan Dust Transport Over the North Atlantic Ocean and Mediterranean: An Overview , 1996 .

[11]  Thomas A. Cahill,et al.  Asian aerosols in North America: Frequency and concentration of fine dust , 2002 .

[12]  Yinon Rudich,et al.  Desert dust suppressing precipitation: A possible desertification feedback loop , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[13]  Paul J. DeMott,et al.  Saharan dust storms and indirect aerosol effects on clouds: CRYSTAL‐FACE results , 2003 .

[14]  T. Gill,et al.  Long‐range transport of North African dust to the eastern United States , 1997 .

[15]  Kinetics of heterogeneous ice nucleation on the surfaces of mineral dust cores inserted into aqueous ammonium sulfate particles , 2003 .

[16]  H. Jonsson,et al.  The cloud, aerosol and precipitation spectrometer: a new instrument for cloud investigations , 2001 .

[17]  J. Prospero.  Long‐term measurements of the transport of African mineral dust to the southeastern United States: Implications for regional air quality , 1999 .

[18]  Robert Frouin,et al.  Asian Dust Events of April 1998 , 2001 .

[19]  John Hallett,et al.  A laboratory study of the ice nucleating properties of some mineral particulates , 1968 .

[20]  A. Ono,et al.  The Nature and the Origin of Ice Nuclei in the .Atmosphere , 1959 .

[21]  K. Gierens.  On the transition between heterogeneous and homogeneous freezing , 2002 .