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Title: Deciphering Atmospheric Ice Nucleation using Molecular-Scale Microscopy.

Abstract

Atmospheric ice affects Earth's radiative properties and initiates most precipitation. Growing ice typically requires a particle, often airborne mineral dust, e.g., to catalyze freezing of supercooled cloud droplets. How chemistry, structure and morphology determine the ice - nucleating ability of minerals remains elusive. Not surprisingly, poor understanding of a erosol - cloud interactions is a major source of uncertainty in climate models. In this project, we combine d optical microscopy with atomic force microscopy t o explore the mechanisms of initial ice formation on alkali feldspar, a mineral proposed to dominate ice nucleation in Earth's atmosphere. When cold air becomes supersaturated with respect to water, we discovered that supercooled liquid water condenses at steps without having to overcome a nucleation barrier, and subsequently freezes quickly. Our results imply that steps, common even on macroscopically flat feldspar surfaces, can accelerate water condensation followed by freezing, thus promoting glaciation and dehydration of mixed - phase clouds. Motivated by the fact that current climate simulations do not properly account for feldspar's extreme efficiency to nucleate ice, we modified DOE's climate model, the Energy Exascale Earth System Model (E3SM), to i ncrease the activation of ice nucleation on feldspar dust. This included add ingmore » a new aerosol tracer into the model and updat ing the ice nucleation parameterization, based on Classical Nucleation Theory, for multiple mineral dust tracers. Although t he se m odifications have little impact on global averages , predictions of regional averages can be strongly affected .« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1569351
Report Number(s):
SAND2019-11159
679808
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English

Citation Formats

Thurmer, Konrad, Friddle, Raymond William, Wheeler, Lauren Bronwyn, Bartelt, Norman Charles., Roesler, Erika Louise, and Kolasinski, Robert. Deciphering Atmospheric Ice Nucleation using Molecular-Scale Microscopy.. United States: N. p., 2019. Web. doi:10.2172/1569351.
Thurmer, Konrad, Friddle, Raymond William, Wheeler, Lauren Bronwyn, Bartelt, Norman Charles., Roesler, Erika Louise, & Kolasinski, Robert. Deciphering Atmospheric Ice Nucleation using Molecular-Scale Microscopy.. United States. doi:10.2172/1569351.
Thurmer, Konrad, Friddle, Raymond William, Wheeler, Lauren Bronwyn, Bartelt, Norman Charles., Roesler, Erika Louise, and Kolasinski, Robert. Sun . "Deciphering Atmospheric Ice Nucleation using Molecular-Scale Microscopy.". United States. doi:10.2172/1569351. https://www.osti.gov/servlets/purl/1569351.
@article{osti_1569351,
title = {Deciphering Atmospheric Ice Nucleation using Molecular-Scale Microscopy.},
author = {Thurmer, Konrad and Friddle, Raymond William and Wheeler, Lauren Bronwyn and Bartelt, Norman Charles. and Roesler, Erika Louise and Kolasinski, Robert},
abstractNote = {Atmospheric ice affects Earth's radiative properties and initiates most precipitation. Growing ice typically requires a particle, often airborne mineral dust, e.g., to catalyze freezing of supercooled cloud droplets. How chemistry, structure and morphology determine the ice - nucleating ability of minerals remains elusive. Not surprisingly, poor understanding of a erosol - cloud interactions is a major source of uncertainty in climate models. In this project, we combine d optical microscopy with atomic force microscopy t o explore the mechanisms of initial ice formation on alkali feldspar, a mineral proposed to dominate ice nucleation in Earth's atmosphere. When cold air becomes supersaturated with respect to water, we discovered that supercooled liquid water condenses at steps without having to overcome a nucleation barrier, and subsequently freezes quickly. Our results imply that steps, common even on macroscopically flat feldspar surfaces, can accelerate water condensation followed by freezing, thus promoting glaciation and dehydration of mixed - phase clouds. Motivated by the fact that current climate simulations do not properly account for feldspar's extreme efficiency to nucleate ice, we modified DOE's climate model, the Energy Exascale Earth System Model (E3SM), to i ncrease the activation of ice nucleation on feldspar dust. This included add ing a new aerosol tracer into the model and updat ing the ice nucleation parameterization, based on Classical Nucleation Theory, for multiple mineral dust tracers. Although t he se m odifications have little impact on global averages , predictions of regional averages can be strongly affected .},
doi = {10.2172/1569351},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {9}
}