Atmos. Chem. Phys. Discuss., 6, 3571-3609, 2006
www.atmos-chem-phys-discuss.net/6/3571/2006/
doi:10.5194/acpd-6-3571-2006
© Author(s) 2006. This work is licensed under the
Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Oxalic acid as a heterogeneous ice nucleus in the upper troposphere and its indirect aerosol effect
B. Zobrist1, C. Marcolli1, T. Koop2, B. P. Luo1, D. M. Murphy3, U. Lohmann1, A. Zardini1, U. K. Krieger1, T. Corti1, D. J. Cziczo1, S. Fueglistaler1, P. K. Hudson3, D. S. Thomson3, and T. Peter1
1Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
2Department of Chemistry, Bielefeld University, Bielefeld, Germany
3Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Colorado, USA

Abstract. Heterogeneous ice freezing points of aqueous solutions containing various immersed solid dicarboxylic acids (oxalic, adipic, succinic, phthalic and fumaric) have been measured with a differential scanning calorimeter. The results show that only the dihydrate of oxalic acid (OAD) acts as a heterogeneous ice nucleus, with an increase in freezing temperature between 2-5 K depending on solution composition. In several field campaigns, oxalic acid enriched particles have been detected in the upper troposphere with single particle aerosol mass spectrometry. Simulations with a microphysical box model indicate that the presence of OAD may reduce the ice particle number density in cirrus clouds by up to ~50% when compared to exclusively homogeneous cirrus formation without OAD. Using the ECHAM4 climate model we estimate the global net radiative effect caused by this heterogeneous freezing to result in a cooling as high as -0.3 Wm-2.

Citation: Zobrist, B., Marcolli, C., Koop, T., Luo, B. P., Murphy, D. M., Lohmann, U., Zardini, A., Krieger, U. K., Corti, T., Cziczo, D. J., Fueglistaler, S., Hudson, P. K., Thomson, D. S., and Peter, T.: Oxalic acid as a heterogeneous ice nucleus in the upper troposphere and its indirect aerosol effect, Atmos. Chem. Phys. Discuss., 6, 3571-3609, doi:10.5194/acpd-6-3571-2006, 2006.
 
Search ACPD
Discussion Paper
    XML
    Citation
    Final Revised Paper
    Share