cellulose
; experimental study
; freezing
; nucleation
; numerical model
; particulate matter
; precipitation (climatology)
英文摘要:
Ice particles in the atmosphere influence clouds, precipitation and climate, and often form with help from aerosols that serve as ice-nucleating particles. Biological particles, including non-proteinaceous ones, contribute to the diverse spectrum of ice-nucleating particles. However, little is known about their atmospheric abundance and ice nucleation efficiency, and their role in clouds and the climate system is poorly constrained. One biological particle type, cellulose, has been shown to exist in an airborne form that is prevalent throughout the year even at remote and elevated locations. Here we report experiments in a cloud simulation chamber to demonstrate that microcrystalline cellulose particles can act as efficient ice-nucleating particles in simulated supercooled clouds. In six immersion mode freezing experiments, we measured the ice nucleation active surface-site densities of aerosolized cellulose across a range of temperatures. Using these active surface-site densities, we developed parameters describing the ice nucleation ability of these particles and applied them to observed atmospheric cellulose and plant debris concentrations in a global aerosol model. We find that ice nucleation by cellulose becomes significant (>0.1l -1) below about -21 °C, temperatures relevant to mixed-phase clouds. We conclude that the ability of cellulose to act as ice-nucleating particles requires a revised quantification of their role in cloud formation and precipitation.
Institute for Meteorology and Climate Research-Atmospheric Aerosol Research, Karlsruhe Institute of Technology, Karlsruhe, Germany; Meteorological Research Institute, Tsukuba, Japan; Snow and Ice Research Center, National Research Institute for Earth Science and Disaster Prevention, Nagaoka, Japan; Institute for Meteorology and Climate Research-Troposphere Research, Karlsruhe Institute of Technology, Karlsruhe, Germany; Faculty of Chemistry, Bielefeld University, Bielefeld, Germany
Recommended Citation:
Hiranuma N.,Möhler O.,Yamashita K.,et al. Ice nucleation by cellulose and its potential contribution to ice formation in clouds[J]. Nature Geoscience,2015-01-01,8(4)