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On the availability of uncoated mineral dust ice nuclei in cold cloud regions
Author(s) -
Wiacek Aldona,
Peter Thomas
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl039429
Subject(s) - ice nucleus , atmospheric sciences , environmental science , mineral dust , relative humidity , clear ice , saturation (graph theory) , liquid water , nucleation , sea ice growth processes , mineral , liquid water content , homogeneous , ice cloud , geology , arctic ice pack , aerosol , meteorology , materials science , climatology , cloud computing , sea ice thickness , antarctic sea ice , physics , earth science , sea ice , thermodynamics , mathematics , computer science , operating system , metallurgy , combinatorics
The ice nucleation efficiency of mineral dust decreases when it acquires coatings, e.g. through processing in liquid clouds. This study explores the availability of unprocessed mineral dust for interactions with clouds. We performed forward trajectory calculations originating near the surface of the Chinese Taklimakan desert. The initial specific humidity of each trajectory was assumed to be conserved and used to calculate the relative humidities with respect to water and ice, allowing us to estimate the formation of liquid, mixed‐phase and ice clouds downstream. Practically none of the simulated air parcels reached conditions suitable for homogeneous nucleation of ice ( T ≲ −40°C) without experiencing water saturation first. Potentially the biggest impact of mineral dust is predicted to be on mixed‐phase clouds. Furthermore, most trajectories passed through ice‐saturated (but water‐subsaturated) regions where “warm” ( T ≳ −40°C) ice clouds may form prior to mixed‐phase clouds.