Aerosol and Clouds
Measurements of heterogeneous ice nuclei in the western United States in springtime and their relation to aerosol characteristics
Article first published online: 31 JAN 2007
Copyright 2007 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 112, Issue D2, 27 January 2007
How to Cite
2007), Measurements of heterogeneous ice nuclei in the western United States in springtime and their relation to aerosol characteristics, J. Geophys. Res., 112, D02209, doi:10.1029/2006JD007500., et al. (
- Issue published online: 31 JAN 2007
- Article first published online: 31 JAN 2007
- Manuscript Accepted: 29 SEP 2006
- Manuscript Revised: 8 SEP 2006
- Manuscript Received: 11 MAY 2006
- ice nuclei;
- mass spectrometry
 The second Ice Nuclei Spectroscopy (INSPECT-II) campaign was conducted at Storm Peak Laboratory in northwestern Colorado in April and May 2004. The physical and chemical characteristics of springtime atmospheric aerosols, including those which act as heterogeneous ice nuclei (IN), were investigated. The ice formation activity of submicron particles was measured with a continuous-flow diffusion chamber. The concentrations of heterogeneous ice nuclei ([IN]) active at −15 to −50°C and water supersaturations −25% < SSw < 0 typically ranged from 1 to 10 std l−1. Aerosol mass spectrometry measurements indicated that the composition of IN had much higher contributions from mineral dust/fly ash and metallic particle types compared to ambient particles of similar sizes. While IN concentration and composition measurements are similar to observations from the same site during INSPECT-I in November 2001, there was considerably more variability in [IN] during INSPECT-II associated with periods of sporadically high [IN]. A relation of [IN] to concentrations of larger particles was noted; however, the predictive utility of such a relationship proved limited during non-dust-related increases in accumulation mode number concentrations. We conclude that the observed high variability and extremes in [IN] during spring are attributable primarily to variations in airborne dust concentrations and that the [IN] observed in spring 2004 represent lower bounds on the expected [IN] at SPL in the spring. On the basis of modeled dust vertical profiles, strong impacts of dust on [IN] might be expected at the higher altitudes of cold clouds.