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OPA: Optical Properties of Aerosol Constituents   -   Claus Jørgen Nielsen


Optical Properties of Aerosols
a laboratory and modelling study

This project has received financial support by the Norwegian Research Council through Grant #134110/S30
   Publications and available datasets, see below.  

Atmospheric aerosols interact with solar and terrestrial radiation. A significant amount of aerosols are of anthropogenic origin and aerosols therefore contribute to man made impact on climate. They have a significant direct impact on the radiative balance by scattering and absorption of solar radiation. In addition, the aerosols influence the radiative balance indirectly by acting as cloud condensation nuclei and thus affect the cloud microphysics and the albedo of the earth. Aerosols act as sites for heterogeneous chemistry, and the sulfate aerosols constitute the basis for the polar stratospheric clouds (PSC's) and are thereby linked to the stratospheric "ozone hole" chemistry in particular, and to the trace gas partitioning in general.

Several anthropogenic aerosol types are known; soot and dust are emitted directly into the atmosphere, but most aerosols are formed from chemical precursors. Each type of particles has different optical properties and different impact on climate. The situation is even more complex as aerosols occur in blends, and the optical properties of blends can deviate much from those derived assuming a linear relationship. Studies of aerosol optical properties have only been made for a limited set of aerosol types. In particular, studies of aerosols with mixed composition are missing.

Papers Supplementary data
Myhre, C.E.L., Christensen, D.H., Nicolaisen, F.M. and Nielsen, C.J.: Spectroscopic Study of Aqueous H2SO4 at Different Temperatures and Compositions: Variations in Dissociation and Optical Properties. Journal of Physical Chemistry A (2003), 107 (12), 1979-1991. Data of complex index of refraction, 6500-400 cm-1 and other tables given as supplementary information and a model to calculate the optical constants for a given concentration and temperature
Myhre, C.E.L. and Nielsen, C.J.: Optical properties of atmospheric fog and cloud droplets collected in the Po Valley, Italy.Asian Chemistry Letters (2003), 7 (2 & 3), 113-118.

Data of complex index of refraction 6500-400 cm-1 and imaginary refractive index in UV/VIS region. Please send an e-mail for the data set:

Grothe, H. Myhre, C.E.L. and Tizek, H.: Vibrational spectra of nitric acid dihydrate (NAD). Vibrational Spectroscopy (2004), 34 (1), 55-62.  
Myhre, G., Berglen, T.F., Myhre, C.E.L. and Isaksen, I.S.A.: The radiative effect of the anthropogenic influence on the stratospheric sulfate aerosol layer, Tellus B, (2004), 56, (3), 294-299, doi:10.1111/j.1600-0889.2004.00106.  
Myhre, C.E.L., D’Anna, B., Nicolaisen, F.M. and Nielsen, C.J.: Properties of Aqueous Methanesulphonic Acid: Complex Index of Refraction and Surface Tension, Applied Optics,(2004), 43 (12), 2500-2509. Data of complex index of refraction and surface tension
Myhre, C.E.L. and Nielsen, C.J.: Optical properties in the UV and visible spectral region of organic acids relevant to tropospheric aerosols, Atmospheric Chemistry and Physics, 4, 1-11, 2004  
Myhre, C.E.L., Grothe, H., Gola, A.A. and Nielsen, C.J.: Optical constants of HNO3/H2O and H2SO4/HNO3/H2O at low temperatures in the infrared region, J. Phys. Chem. A, submitted Data of complex index of refraction, 6500-500 cm-1 of mixtures HNO3/H2O and H2SO4/HNO3/H2O at different temperatures