The effects of hygroscopicity on ice nucleation of fossil fuel combustion aerosols in mixed-phase clouds

Abstract. Fossil fuel black carbon and organic matter (ffBC/OM) are often emitted together with sulfate, which coats the surface of these particles and changes their hygroscopicity. Observational studies at cirrus temperatures (≈−40 °C) show that the hygroscopicity of soot particles can modulate their ice nucleation ability. Here, we implement a scheme for 3 categories of soot (hydrophobic, hydrophilic and hygroscopic) on the basis of laboratory data and specify their ability to act as ice nuclei at mixed-phase temperatures by extrapolating the observations using a published deposition/condensation/immersion freezing parameterization. The new scheme results in significant changes to anthropogenic forcing in mixed-phase clouds. The net forcing in our offline model studies varies from 0.111 to 1.059 W m−2 depending on the ice nucleation capability of hygroscopic soot particles. The total anthropogenic cloud forcing and whole-sky forcing with the new scheme are 0.06 W m−2 and −2.45 W m−2, respectively, but could be more positive (by about 1.17 W m−2) if hygroscopic soot particles are allowed to nucleate ice particles. The change in liquid water path dominates the anthropogenic forcing in mixed-phase clouds.

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The effects of hygroscopicity of fossil fuel combustion aerosols on mixed-phase clouds

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-19987-2012 ◽

2012 ◽

Vol 12 (8) ◽

pp. 19987-20006

Author(s):

Y. Yun ◽

J. E. Penner ◽

O. Popovicheva

Keyword(s):

Fossil Fuel ◽

Laboratory Data ◽

Ice Nucleation ◽

Mixed Phase ◽

Liquid Water Path ◽

Anthropogenic Forcing ◽

Soot Particles ◽

Cloud Forcing ◽

Ice Nuclei ◽

Mixed Phase Clouds

Abstract. Fossil fuel black carbon and organic matter (ffBC/OM) are often emitted together with sulfate, which coats the surface of these particles and changes their hygroscopicity. Observational studies show that the hygroscopicity of soot particles can modulate their ice nucleation ability. To address this, we implemented a scheme that uses 3 levels of soot hygroscopicity (hydrophobic, hydrophilic and hygroscopic) and used laboratory data to specify their ice nuclei abilities. The new scheme results in significant changes to anthropogenic forcing in mixed-phase clouds. The net forcing in off-line studies varies from 0.111 to 1.059 W m−2 depending on the ice nucleation capability of hygroscopic soot particles. The total anthropogenic cloud forcing and whole-sky forcing with the new scheme is 0.06 W m−2 and −2.45 W m−2, respectively, but could be more positive if hygroscopic soot particles are allowed to nucleate ice particles. The change in liquid water path dominates the anthropogenic forcing in mixed-phase clouds.

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Condensed-phase biogenic–anthropogenic interactions with implications for cold cloud formation

Faraday Discussions ◽

10.1039/c7fd00010c ◽

2017 ◽

Vol 200 ◽

pp. 165-194 ◽

Cited By ~ 14

Author(s):

Joseph C. Charnawskas ◽

Peter A. Alpert ◽

Andrew T. Lambe ◽

Thomas Berkemeier ◽

Rachel E. O’Brien ◽

...

Keyword(s):

Freezing Temperature ◽

Organic Aerosol ◽

Ice Nucleation ◽

Mixed Phase ◽

Cloud Formation ◽

Fossil Fuel Combustion ◽

Soot Particles ◽

Ice Nuclei ◽

Deliquescence Relative Humidity ◽

Homogeneous Freezing

Anthropogenic and biogenic gas emissions contribute to the formation of secondary organic aerosol (SOA). When present, soot particles from fossil fuel combustion can acquire a coating of SOA. We investigate SOA–soot biogenic–anthropogenic interactions and their impact on ice nucleation in relation to the particles’ organic phase state. SOA particles were generated from the OH oxidation of naphthalene, α-pinene, longifolene, or isoprene, with or without the presence of sulfate or soot particles. Corresponding particle glass transition (Tg) and full deliquescence relative humidity (FDRH) were estimated using a numerical diffusion model. Longifolene SOA particles are solid-like and all biogenic SOA sulfate mixtures exhibit a core–shell configuration (i.e.a sulfate-rich core coated with SOA). Biogenic SOA with or without sulfate formed ice at conditions expected for homogeneous ice nucleation, in agreement with respectiveTgand FDRH. α-pinene SOA coated soot particles nucleated ice above the homogeneous freezing temperature with soot acting as ice nuclei (IN). At lower temperatures the α-pinene SOA coating can be semisolid, inducing ice nucleation. Naphthalene SOA coated soot particles acted as ice nuclei above and below the homogeneous freezing limit, which can be explained by the presence of a highly viscous SOA phase. Our results suggest that biogenic SOA does not play a significant role in mixed-phase cloud formation and the presence of sulfate renders this even less likely. However, anthropogenic SOA may have an enhancing effect on cloud glaciation under mixed-phase and cirrus cloud conditions compared to biogenic SOA that dominate during pre-industrial times or in pristine areas.

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Understanding the Extratropical Liquid Water Path Feedback in Mixed-Phase Clouds with an Idealized Global Climate Model

Journal of Climate ◽

10.1175/jcli-d-21-0334.1 ◽

2022 ◽

pp. 1-48

Author(s):

Yi Ming

Keyword(s):

Water Content ◽

Liquid Water ◽

Climate Model ◽

Global Climate Model ◽

Cloud Water ◽

Mixed Phase ◽

Liquid Water Path ◽

Water Path ◽

Cloud Water Content ◽

Mixed Phase Clouds

Abstract A negative shortwave cloud feedback associated with higher extratropical liquid water content in mixed-phase clouds is a common feature of global warming simulations, and multiple mechanisms have been hypothesized. A set of process-level experiments performed with an idealized global climate model (a dynamical core with passive water and cloud tracers and full Rotstayn-Klein single-moment microphysics) show that the common picture of the liquid water path (LWP) feedback in mixed-phase clouds being controlled by the amount of ice susceptible to phase change is not robust. Dynamic condensate processes—rather than static phase partitioning—directly change with warming, with varied impacts on liquid and ice amounts. Here, three principal mechanisms are responsible for the LWP response, namely higher adiabatic cloud water content, weaker liquid-to-ice conversion through the Bergeron-Findeisen process, and faster melting of ice and snow to rain. Only melting is accompanied by a substantial loss of ice, while the adiabatic cloud water content increase gives rise to a net increase in ice water path (IWP) such that total cloud water also increases without an accompanying decrease in precipitation efficiency. Perturbed parameter experiments with a wide range of climatological LWP and IWP demonstrate a strong dependence of the LWP feedback on the climatological LWP and independence from the climatological IWP and supercooled liquid fraction. This idealized setup allows for a clean isolation of mechanisms and paints a more nuanced picture of the extratropical mixed-phase cloud water feedback than simple phase change.

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Towards a molecular-based parameterization of the ice nucleation activity of biological macromolecules and its implications for aerosol-cloud interactions

10.5194/egusphere-egu21-2073 ◽

2021 ◽

Author(s):

Minghui Zhang ◽

Amina Khaled ◽

Pierre Amato ◽

Anne-Marie Delort ◽

Barbara Ervens

Keyword(s):

Fungal Spores ◽

Chemical Properties ◽

Active Surface ◽

Ice Nucleation ◽

Mixed Phase ◽

Biological Macromolecules ◽

Cloud Properties ◽

Nucleation Activity ◽

Mixed Phase Clouds ◽

Ice Nucleation Activity

Primary biological aerosol particles (PBAPs) play an important role in mixed-phase clouds as they nucleate ice even at temperatures of T > -10 &#176;C. Current parameterizations of PBAP ice nucleation are based on ice nucleation active surface site (INAS) densities that are derived from freezing experiments. However, only a small fraction of the PBAP surface is responsible for their ice nucleation activity, such as proteins of bacteria cells, fungal spores, pollen polysaccharides and other (unidentified) macromolecules. Based on literature data, we refine the INAS density parameterizations by further parameters:1) We demonstrate that the ice nucleation activity of such individual macromolecules is much higher than that of PBAPs. It can be shown that INAS of PBAPs can be scaled by the surface fraction of these ice-nucleating molecules.2) Previous studies suggested that ice nucleation activity tends to be higher for larger macromolecules and their aggregates. We show that these trends hold true for various groups of macromolecules that comprise PBAPs.Based on these trends, we suggest a more refined parameterization for ice-nucleating macromolecules in different types of PBAPs and even for different species of bacteria, fungi, and pollen. This new parameterization can be considered a step towards a molecular-based approach to predict the ice nucleation activity of the macromolecules in PBAPs based on their biological and chemical properties.We implement both the traditional INAS parameterization for complete PBAPs and our parameterization for individual molecules in an adiabatic cloud parcel model. The extent will be discussed to which the two parameterizations result in different cloud properties of mixed-phase clouds.

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Ice Nucleation in Mixed-Phase Clouds

Mixed-Phase Clouds ◽

10.1016/b978-0-12-810549-8.00002-7 ◽

2018 ◽

pp. 13-41 ◽

Cited By ~ 2

Author(s):

Thomas F. Whale

Keyword(s):

Ice Nucleation ◽

Mixed Phase ◽

Mixed Phase Clouds

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Ice Particle Production in Mid-level Stratiform Mixed-phase Clouds Observed with Collocated A-Train Measurements

10.5194/acp-2017-927 ◽

2017 ◽

Author(s):

Damao Zhang ◽

Zhien Wang ◽

Pavlos Kollias ◽

Andrew M. Vogelmann ◽

Kang Yang ◽

...

Keyword(s):

Northern Hemisphere ◽

Particle Production ◽

Climate Models ◽

Global Scale ◽

Number Concentration ◽

Mixed Phase ◽

Liquid Water Path ◽

Lidar Measurements ◽

Dust Events ◽

Mixed Phase Clouds

Abstract. Collocated CloudSat radar and CALIPSO lidar measurements between 2006 and 2010 are analyzed to study primary ice particle production characteristics in mid-level stratiform mixed-phase clouds on a global scale. For similar clouds in terms of cloud top temperature and liquid water path, Northern Hemisphere latitude bands have layer-maximum radar reflectivity (ZL) that is ~1 to 8 dBZ larger than their counterparts in the Southern Hemisphere. The systematically larger ZL under similar cloud conditions suggests larger ice number concentrations in mid-level stratiform mixed-phase clouds over the Northern Hemisphere, which is possibly related to higher background aerosol loadings. Furthermore, we show that northern mid- and high-latitude springtime has ZL that is larger by up to 8 dBZ (a factor of 6 higher ice number concentration) than other seasons, which might be related to more dust events that provide effective ice nucleating particles. Our study suggests that aerosol-dependent ice number concentration parameterizations are required in climate models to improve mixed-phase cloud simulations, especially over the Northern Hemisphere.

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Understanding the Extratropical Liquid Water Path Feedback in Mixed-Phase Clouds with an Idealized Global Climate Model

10.1002/essoar.10506935.1 ◽

2021 ◽

Author(s):

Michelle Frazer ◽

Yi Ming

Keyword(s):

Liquid Water ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Mixed Phase ◽

Liquid Water Path ◽

Water Path ◽

Mixed Phase Clouds

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The Horizontal Ice Nucleation Chamber (HINC): INP measurements at conditions relevant for mixed-phase clouds at the High Altitude Research Station Jungfraujoch

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-15199-2017 ◽

2017 ◽

Vol 17 (24) ◽

pp. 15199-15224 ◽

Cited By ~ 17

Author(s):

Larissa Lacher ◽

Ulrike Lohmann ◽

Yvonne Boose ◽

Assaf Zipori ◽

Erik Herrmann ◽

...

Keyword(s):

High Altitude ◽

Ice Nucleation ◽

Mixed Phase ◽

Saharan Dust ◽

Research Station ◽

Minimum Detectable Concentration ◽

The North ◽

New Instrument ◽

Marine Air ◽

Mixed Phase Clouds

Abstract. In this work we describe the Horizontal Ice Nucleation Chamber (HINC) as a new instrument to measure ambient ice-nucleating particle (INP) concentrations for conditions relevant to mixed-phase clouds. Laboratory verification and validation experiments confirm the accuracy of the thermodynamic conditions of temperature (T) and relative humidity (RH) in HINC with uncertainties in T of ±0.4 K and in RH with respect to water (RHw) of ±1.5 %, which translates into an uncertainty in RH with respect to ice (RHi) of ±3.0 % at T > 235 K. For further validation of HINC as a field instrument, two measurement campaigns were conducted in winters 2015 and 2016 at the High Altitude Research Station Jungfraujoch (JFJ; Switzerland, 3580 m a. s. l. ) to sample ambient INPs. During winters 2015 and 2016 the site encountered free-tropospheric conditions 92 and 79 % of the time, respectively. We measured INP concentrations at 242 K at water-subsaturated conditions (RHw = 94 %), relevant for the formation of ice clouds, and in the water-supersaturated regime (RHw = 104 %) to represent ice formation occurring under mixed-phase cloud conditions. In winters 2015 and 2016 the median INP concentrations at RHw = 94 % was below the minimum detectable concentration. At RHw = 104 %, INP concentrations were an order of magnitude higher, with median concentrations in winter 2015 of 2.8 per standard liter (std L−1; normalized to standard T of 273 K and pressure, p, of 1013 hPa) and 4.7 std L−1 in winter 2016. The measurements are in agreement with previous winter measurements obtained with the Portable Ice Nucleation Chamber (PINC) of 2.2 std L−1 at the same location. During winter 2015, two events caused the INP concentrations at RHw = 104 % to significantly increase above the campaign average. First, an increase to 72.1 std L−1 was measured during an event influenced by marine air, arriving at the JFJ from the North Sea and the Norwegian Sea. The contribution from anthropogenic or other sources can thereby not be ruled out. Second, INP concentrations up to 146.2 std L−1 were observed during a Saharan dust event. To our knowledge this is the first time that a clear enrichment in ambient INP concentration in remote regions of the atmosphere is observed during a time of marine air mass influence, suggesting the importance of marine particles on ice nucleation in the free troposphere.

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Contribution of feldspar and marine organic aerosols to global ice nucleating particle concentrations

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-3637-2017 ◽

2017 ◽

Vol 17 (5) ◽

pp. 3637-3658 ◽

Cited By ~ 63

Author(s):

Jesús Vergara-Temprado ◽

Benjamin J. Murray ◽

Theodore W. Wilson ◽

Daniel O'Sullivan ◽

Jo Browse ◽

...

Keyword(s):

Regional Distribution ◽

Organic Aerosols ◽

Field Measurements ◽

Field Work ◽

Ice Nucleation ◽

Mixed Phase ◽

Aerosol Composition ◽

Desert Dust ◽

Concentration Changes ◽

Mixed Phase Clouds

Abstract. Ice-nucleating particles (INPs) are known to affect the amount of ice in mixed-phase clouds, thereby influencing many of their properties. The atmospheric INP concentration changes by orders of magnitude from terrestrial to marine environments, which typically contain much lower concentrations. Many modelling studies use parameterizations for heterogeneous ice nucleation and cloud ice processes that do not account for this difference because they were developed based on INP measurements made predominantly in terrestrial environments without considering the aerosol composition. Errors in the assumed INP concentration will influence the simulated amount of ice in mixed-phase clouds, leading to errors in top-of-atmosphere radiative flux and ultimately the climate sensitivity of the model. Here we develop a global model of INP concentrations relevant for mixed-phase clouds based on laboratory and field measurements of ice nucleation by K-feldspar (an ice-active component of desert dust) and marine organic aerosols (from sea spray). The simulated global distribution of INP concentrations based on these two species agrees much better with currently available ambient measurements than when INP concentrations are assumed to depend only on temperature or particle size. Underestimation of INP concentrations in some terrestrial locations may be due to the neglect of INPs from other terrestrial sources. Our model indicates that, on a monthly average basis, desert dusts dominate the contribution to the INP population over much of the world, but marine organics become increasingly important over remote oceans and they dominate over the Southern Ocean. However, day-to-day variability is important. Because desert dust aerosol tends to be sporadic, marine organic aerosols dominate the INP population on many days per month over much of the mid- and high-latitude Northern Hemisphere. This study advances our understanding of which aerosol species need to be included in order to adequately describe the global and regional distribution of INPs in models, which will guide ice nucleation researchers on where to focus future laboratory and field work.

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