Mineral dust is an important source of ice nucleating particles (INPs) for mixed-phase clouds and can influence cloud properties, precipitation, and radiative forcing. However, the ice nucleation property of natural dust and its response to atmospheric aging remain poorly constrained. Here, we investigated the immersion freezing (IMF) of surface-collected dust from Tengger Desert in China and further examined the effects of mixing with ammonium sulfate (AS), NaCl, H₂SO₄, and HNO₃ and heating treatments. Tengger Desert dust exhibits efficient immersion freezing ability. Median freezing temperature (T₅₀) of Tengger Desert dust increased from 251.6 K to 256.7 K as the dust mass fraction increase from 1.4´10^-4 wt% to 1.0´10^-1 wt%. A minor increase of feldspar (~2% in number or surface area) quantified by single particle analysis enhanced the ice nucleation active site density (N_s) by approximately one order of magnitude. AS enhanced the IMF activity of the investigated dust, and the increase of T₅₀, N_s, and heterogeneous ice nucleation rate coefficient (J_het) exhibited a sigmoidal increase with increasing AS concentration. The enhancement is associated with NH₄⁺ adsorption on dust surface. NaCl, acid, and heating treatment had no impacts on the overall IMF with respect to T₅₀, although minor responses were observed for labile ice active sites above 256 K. Parameterizations of N_s and J_het for Tengger Desert dust and dust mixed with AS were developed based on the experimental data. This study provides the experimentally constrained parameterizations for Asian desert dust and improves the understanding of atmospheric aging effects on the ice nucleation of natural dust.
 

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