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research article

Sensitivity of the global distribution of cirrus ice crystal concentration to heterogeneous freezing

Barahona, D.
•
Rodriguez, J.
•
Nenes, Athanasios  
2010
Journal of Geophysical Research Atmospheres

This study presents the sensitivity of global ice crystal number concentration, N<inf>c</inf>, to the parameterization of heterogeneous ice nuclei (IN). Simulations are carried out with the NASA Global Modeling Initiative chemical and transport model coupled to an analytical ice microphysics parameterization. Heterogeneous freezing is described using nucleation spectra derived from theoretical considerations and empirical data for dust, black carbon, ammonium sulfate, and glassy aerosol as IN precursors. When competition between homogeneous and heterogeneous freezing is considered, global mean N<inf>c</inf> vary by up to a factor of twenty depending on the heterogeneous freezing spectrum used. IN effects on N<inf>c</inf> strongly depend on dust and black carbon concentrations and are strongest under conditions of weak updraft and high temperature. Regardless of the heterogeneous spectrum used, dust is an important contributor of IN over large regions of the Northern Hemisphere. Black carbon however exhibits appreciable effects on N<inf>c</inf> when the freezing fraction is greater than 1%. Compared to in situ observations, N<inf>c</inf> is overpredicted at temperatures below 205 K, even if a fraction of liquid aerosol is allowed to act as glassy IN. Assuming that cirrus formation is forced by weak updraft addressed this overprediction but promoted heterogeneous freezing effects to the point where homogeneous freezing is inhibited for IN concentrations as low as 1 L-1. Chemistry and dynamics must be considered to explain cirrus characteristics at low temperature. Only cloud formation scenarios where competition between homogeneous and heterogeneous freezing is the dominant feature would result in maximum supersaturation levels consistent with observations. Copyright 2010 by the American Geophysical Union.

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Type
research article
DOI
10.1029/2010JD014273
Author(s)
Barahona, D.
•
Rodriguez, J.
•
Nenes, Athanasios  
Date Issued

2010

Publisher

Blackwell Publishing Ltd

Published in
Journal of Geophysical Research Atmospheres
Volume

115

D23

Article Number

D23213

Subjects

Ammonium compounds

•

Atmospheric aerosols

•

Chemical analysis

•

Clouds

•

Competition

•

Computer simulation

•

Concentration (process)

•

Dust

•

Freezing

•

Glassy carbon

•

NASA

•

Particulate emissions

•

Ammonium Sulfate

•

Black carbon

•

Chemical and transport models

•

Cirrus formation

•

Cloud formation

•

Empirical data

•

Global distribution

•

Global modeling

•

Heterogeneous freezing

•

High temperature

•

Ice crystals

•

Ice nuclei

•

In-situ observations

•

Large regions

•

Liquid aerosols

•

Low temperatures

•

Microphysics parameterization

•

Northern Hemispheres

•

Number concentration

•

Ice

•

ammonium sulfate

•

black carbon

•

cirrus

•

dust

•

freezing

•

geographical distribution

•

ice crystal

•

in situ measurement

•

Northern Hemisphere

•

parameterization

•

sensitivity analysis

•

supersaturation

•

temperature anomaly

Peer reviewed

REVIEWED

Written at

OTHER

EPFL units
LAPI  
Available on Infoscience
October 15, 2018
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/149025
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