Journal ArticleDOI
High‐frequency gravity waves and homogeneous ice nucleation in tropical tropopause layer cirrus
Eric J. Jensen,Rei Ueyama,Leonhard Pfister,T. V. Bui,M. Joan Alexander,Aurélien Podglajen,Albert Hertzog,Sarah Woods,R. Paul Lawson,Ji-Eun Kim,Mark R. Schoeberl +10 more
TLDR
In this article, the impact of high-frequency gravity waves on homogeneous-freezing ice nucleation in cold cirrus clouds is examined using parcel model simulations driven by superpressure balloon measurements of temperature variability experienced by air parcels in the tropical tropopause region.Abstract:
The impact of high-frequency gravity waves on homogeneous-freezing ice nucleation in cold cirrus clouds is examined using parcel model simulations driven by superpressure balloon measurements of temperature variability experienced by air parcels in the tropical tropopause region. We find that the primary influence of high-frequency waves is to generate rapid cooling events that drive production of numerous ice crystals. Quenching of ice nucleation events by temperature tendency reversal in the highest-frequency waves does occasionally produce low ice concentrations, but the overall impact of high-frequency waves is to increase the occurrence of high ice concentrations. The simulated ice concentrations are considerably higher than indicated by in situ measurements of cirrus in the tropical tropopause region. One-dimensional simulations suggest that although sedimentation reduces mean ice concentrations, a discrepancy of about a factor of 3 with observed ice concentrations remains. Reconciliation of numerical simulations with the observed ice concentrations will require inclusion of physical processes such as heterogeneous nucleation and entrainment.read more
Citations
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Developing a Cloud Scheme With Prognostic Cloud Fraction and Two Moment Microphysics for ECHAM-HAM
Steffen Muench,Ulrike Lohmann +1 more
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The Impact of Mesoscale Gravity Waves on Homogeneous Ice Nucleation in Cirrus Clouds
TL;DR: In this article, the effects of mesoscale gravity waves on homogeneous aerosol freezing in midlatitude cirrus are studied by means of parcel model simulations that are driven by random vertical wind speeds constrained by balloon measurements.
Journal ArticleDOI
Nonturbulent Liquid-Bearing Polar Clouds: Observed Frequency of Occurrence and Simulated Sensitivity to Gravity Waves
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Microscale characteristics of homogeneous freezing events in cirrus clouds
Bernd Kärcher,Eric J. Jensen +1 more
TL;DR: In this paper, the authors investigated the effects of turbulent diffusion and entrainment mixing on the formation of aqueous aerosol particle in a cirrus cloud and found that the freezing time scales and vertical extensions of freezing layers are highly transient and localized.
Journal ArticleDOI
Rapidly Evolving Cirrus Clouds Modulated by Convectively Generated Gravity Waves
TL;DR: In this paper, gravity buoyancy waves generated by a storm in Northern Australia on 13 November 2015 caused an observable rippling effect on cirrus clouds up to 1,000 km away, as seen by the recently launched Himawari-8/9 geostationary satellite.
References
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Journal ArticleDOI
Water activity as the determinant for homogeneous ice nucleation in aqueous solutions
TL;DR: This work shows from experimental data that the homogeneous nucleation of ice from supercooled aqueous solutions is independent of the nature of the solute, but depends only on the water activity of the solution, and presents a thermodynamic theory for homogeneous ice nucleation, which expresses the nucleation rate coefficient as a function of water activity and pressure.
Journal ArticleDOI
Clarifying the Dominant Sources and Mechanisms of Cirrus Cloud Formation
Daniel J. Cziczo,Karl D. Froyd,Karl D. Froyd,Corinna Hoose,Eric J. Jensen,Minghui Diao,Mark A. Zondlo,Jessica B. Smith,Cynthia H. Twohy,Daniel M. Murphy +9 more
TL;DR: Results demonstrate that mineral dust and metallic particles are the dominant source of residual particles, whereas sulfate and organic particles are underrepresented, and elemental carbon and biological materials are essentially absent.
Journal ArticleDOI
The 2D-S (Stereo) Probe: Design and Preliminary Tests of a New Airborne, High-Speed, High-Resolution Particle Imaging Probe
TL;DR: In this paper, the design, laboratory calibrations, and flight tests of a new optical imaging instrument, the twodimensional stereo (2D-S) probe, are presented.
Journal ArticleDOI
A parameterization of cirrus cloud formation: Homogeneous freezing of supercooled aerosols
Bernd Kärcher,Ulrike Lohmann +1 more
TL;DR: In this paper, the number of ice crystals formed via homogeneous freezing of aqueous solution droplets is rather insensitive to details of the aerosol size distribution, but increases rapidly with updraft velocity and decreases with temperature.
Journal ArticleDOI
Heterogeneous nucleation of ice particles on glassy aerosols under cirrus conditions
Benjamin J. Murray,T. W. Wilson,S. Dobbie,Zhiqiang Cui,Sardar M. R. K. Al-Jumur,Ottmar Möhler,Martin Schnaiter,Robert Wagner,Stefan Benz,M. Niemand,Harald Saathoff,Volker Ebert,Volker Ebert,Steven Wagner,Bernd Kärcher +14 more
TL;DR: In this paper, it was shown that heterogeneous nucleation of ice on glassy solution droplets is an important mechanism for ice nucleation in the tropical tropopause layer.
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