Effects of Aerosol Solubility and Regeneration on Mixed-Phase Orographic Clouds and Precipitation

2012 ◽  
Vol 69 (6) ◽  
pp. 1994-2010 ◽  
Author(s):  
Lulin Xue ◽  
Amit Teller ◽  
Roy Rasmussen ◽  
Istvan Geresdi ◽  
Zaitao Pan ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Precipitation Amount ◽  
Forecast Model ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Two Dimensional ◽  
Microphysics Scheme ◽  
Orographic Clouds ◽  
Mixed Phase Clouds ◽  
Aerosol Properties

Abstract A detailed bin aerosol-microphysics scheme has been implemented into the Weather Research and Forecast Model to investigate the effects of aerosol solubility and regeneration on mixed-phase orographic clouds and precipitation. Two-dimensional simulations of idealized moist flow over two identical bell-shaped mountains were carried out using different combinations of aerosol regeneration, solubility, loading, ice nucleation parameterizations, and humidity. The results showed the following. 1) Pollution and regenerated aerosols suppress the riming process in mixed-phase clouds by narrowing the drop spectrum. In general, the lower the aerosol solubility, the broader the drop spectrum and thus the higher the riming rate. When the solubility of initial aerosol increases with an increasing size of aerosol particles, the modified solubility of regenerated aerosols reduces precipitation. 2) The qualitative effects of aerosol solubility and regeneration on mixed-phase orographic clouds and precipitation are not affected by different ice nucleation parameterizations. 3) The impacts of aerosol properties on rain are similar in both warm- and mixed-phase clouds. Aerosols exert weaker impact on snow and stronger impact on graupel compared to rain as graupel production is strongly affected by riming. 4) Precipitation of both warm- and mixed-phase clouds is most sensitive to aerosol regeneration, then to aerosol solubility, and last to modified solubility of regenerated aerosol; however, the precipitation amount is mainly controlled by humidity and aerosol loading.

scholarly journals The efficiency of secondary organic aerosol particles to act as ice nucleating particles at mixed-phase cloud conditions

2018 ◽  
Author(s):  
Wiebke Frey ◽  
Dawei Hu ◽  
James Dorsey ◽  
M. Rami Alfarra ◽  
Aki Pajunoja ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Aerosol Particles ◽  
Organic Aerosol ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Dust Particles ◽  
Ice Cloud ◽  
Liquid Saturation ◽  
Reference Experiment ◽  
Mixed Phase Clouds

Abstract. Secondary Organic Aerosol (SOA) particles have been found to be efficient ice nucleating particles under the cold conditions of (tropical) upper tropospheric cirrus clouds. Whether they also are efficient at initiating freezing at slightly warmer conditions as found in mixed phase clouds remains undetermined. Here, we study the ice nucleating ability of photo-chemically produced SOA particles with the combination of the Manchester Aerosol and Ice Cloud Chambers. Three SOA systems were tested resembling biogenic/anthropogenic particles and particles of different phase state. After the aerosol particles were formed, they were transferred into the cloud chamber where subsequent quasi-adiabatic cloud evacuations were performed. Additionally, the ice forming abilities of ammonium sulfate and kaolinite were investigated as a reference to test the experimental setup. Clouds were formed in the temperature range of −20 °C to −28.6 °C. Only the reference experiment using dust particles showed evidence of ice nucleation. No ice particles were observed in any other experiment. Thus, we conclude that SOA particles produced under the conditions of the reported experiments are not efficient ice nucleating particles starting at liquid saturation under mixed-phase cloud conditions.

scholarly journals Ice nucleation by combustion ash particles at conditions relevant to mixed-phase clouds

2014 ◽  
Vol 14 (21) ◽  
pp. 28845-28883
Author(s):  
N. S. Umo ◽  
B. J. Murray ◽  
M. T. Baeza-Romero ◽  
J. M. Jones ◽  
A. R. Lea-Langton ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Coal Fly Ash ◽  
Aerosol Particles ◽  
Bottom Ash ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Dust Particles ◽  
Cloud Properties ◽  
Mixed Phase Clouds ◽  
The Impact

Abstract. Ice nucleating particles can modify cloud properties with implications for climate and the hydrological cycle; hence, it is important to understand which aerosol particle types nucleate ice and how efficiently they do so. It has been shown that aerosol particles such as natural dusts, volcanic ash, bacteria and pollen can act as ice nucleating particles, but the ice nucleating ability of combustion ashes has not been studied. Combustion ashes are major by-products released during the combustion of solid fuels and a significant amount of these ashes are emitted into the atmosphere either during combustion or via aerosolization of bottom ashes. Here, we show that combustion ashes (coal fly ash, wood bottom ash, domestic bottom ash, and coal bottom ash) nucleate ice in the immersion mode at conditions relevant to mixed-phase clouds. Hence, combustion ashes could play an important role in primary ice formation in mixed-phase clouds, especially in clouds that are formed near the emission source of these aerosol particles. In order to quantitatively assess the impact of combustion ashes on mixed-phase clouds, we propose that the atmospheric abundance of combustion ashes should be quantified since up to now they have mostly been classified together with mineral dust particles. Also, in reporting ice residue compositions, a distinction should be made between natural mineral dusts and combustion ashes in order to quantify the contribution of combustion ashes to atmospheric ice nucleation.

scholarly journals Ice nucleation by combustion ash particles at conditions relevant to mixed-phase clouds

2015 ◽  
Vol 15 (9) ◽  
pp. 5195-5210 ◽  
Author(s):  
N. S. Umo ◽  
B. J. Murray ◽  
M. T. Baeza-Romero ◽  
J. M. Jones ◽  
A. R. Lea-Langton ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Coal Fly Ash ◽  
Aerosol Particles ◽  
Bottom Ash ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Dust Particles ◽  
Cloud Properties ◽  
Mixed Phase Clouds ◽  
The Impact

Abstract. Ice-nucleating particles can modify cloud properties with implications for climate and the hydrological cycle; hence, it is important to understand which aerosol particle types nucleate ice and how efficiently they do so. It has been shown that aerosol particles such as natural dusts, volcanic ash, bacteria and pollen can act as ice-nucleating particles, but the ice-nucleating ability of combustion ashes has not been studied. Combustion ashes are major by-products released during the combustion of solid fuels and a significant amount of these ashes are emitted into the atmosphere either during combustion or via aerosolization of bottom ashes. Here, we show that combustion ashes (coal fly ash, wood bottom ash, domestic bottom ash, and coal bottom ash) nucleate ice in the immersion mode at conditions relevant to mixed-phase clouds. Hence, combustion ashes could play an important role in primary ice formation in mixed-phase clouds, especially in clouds that are formed near the emission source of these aerosol particles. In order to quantitatively assess the impact of combustion ashes on mixed-phase clouds, we propose that the atmospheric abundance of combustion ashes should be quantified since up to now they have mostly been classified together with mineral dust particles. Also, in reporting ice residue compositions, a distinction should be made between natural mineral dusts and combustion ashes in order to quantify the contribution of combustion ashes to atmospheric ice nucleation.

scholarly journals Impact of Air Mass Conditions and Aerosol Properties on Ice Nucleating Particle Concentrations at the High Altitude Research Station Jungfraujoch

Atmosphere ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 363 ◽  
Author(s):  
Larissa Lacher ◽  
Martin Steinbacher ◽  
Nicolas Bukowiecki ◽  
Erik Herrmann ◽  
Assaf Zipori ◽  
...  
Keyword(s):  
High Altitude ◽  
Correlation Coefficients ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
High Time Resolution ◽  
Research Station ◽  
Free Troposphere ◽  
Long Term Study ◽  
Mixed Phase Clouds ◽  
Aerosol Properties

Ice nucleation is the source of primary ice crystals in mixed-phase clouds. Only a small fraction of aerosols called ice nucleating particles (INPs) catalyze ice formation, with their nature and origin remaining unclear. In this study, we investigate potential predictor parameters of meteorological conditions and aerosol properties for INP concentrations at mixed-phase cloud condition at 242 K. Measurements were conducted at the High Altitude Research Station Jungfraujoch (Switzerland, 3580 m a.s.l.), which is located predominantly in the free troposphere (FT) but can occasionally receive injections from the boundary layer (BLI). Measurements are taken during a long-term study of eight field campaigns, allowing for the first time an interannual (2014–2017) and seasonal (spring, summer, and winter) distinction of high-time-resolution INP measurements. We investigate ranked correlation coefficients between INP concentrations and meteorological parameters and aerosol properties. While a commonly used parameterization lacks in predicting the observed INP concentrations, the best INP predictor is the total available surface area of the aerosol particles, with no obvious seasonal trend in the relationship. Nevertheless, the predicting capability is less pronounced in the FT, which might be caused by ageing effects. Furthermore, there is some evidence of anthropogenic influence on INP concentrations during BLI. Our study contributes to an improved understanding of ice nucleation in the free troposphere, however, it also underlines that a knowledge gap of ice nucleation in such an environment exists.

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

2013 ◽  
Vol 13 (8) ◽  
pp. 4339-4348 ◽  
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 ◽  
Model Studies ◽  
Ability To Act ◽  
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.

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

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

<p>Primary biological aerosol particles (PBAPs) play an important role in mixed-phase clouds as they nucleate ice even at temperatures of T > -10 °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:</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p>

scholarly journals Effects of Cloud Condensation Nuclei and Ice Nucleating Particles on Precipitation Processes and Supercooled Liquid in Mixed-phase Orographic Clouds

2016 ◽  
Author(s):  
Jiwen Fan ◽  
L. Ruby Leung ◽  
Daniel Rosenfeld ◽  
Paul J. DeMott
Keyword(s):  
Water Content ◽  
Sierra Nevada ◽  
Cloud Condensation Nuclei ◽  
Supercooled Water ◽  
Mixed Phase ◽  
Condensation Nuclei ◽  
Local Circulation ◽  
Orographic Clouds ◽  
Snow Precipitation ◽  
Mixed Phase Clouds

Abstract. How orographic mixed-phase clouds respond to the change of cloud condensation nuclei (CCN) and ice nucleating particles (INPs) are highly uncertain. The main snow production mechanism in warm and cold mixed-phase orographic clouds (referred to as WMOC and CMOC, respectively, distinguished here as those having cloud tops warmer and colder than −20 °C) could be very different. We quantify the CCN and INP impacts on supercooled water content, cloud phases and precipitation for a WMOC and a CMOC case with a set of sensitivity tests. It is found that deposition plays a more important role than riming for forming snow in the CMOC, while the role of riming is dominant in the WMOC case. As expected, adding CCN suppresses precipitation especially in WMOC and low INP. However, this reverses strongly for CCN > 1000 cm−3. We find a new mechanism through which CCN can invigorate mixed-phase clouds over the Sierra Nevada Mountains and drastically intensify snow precipitation when CCN concentrations are high (1000 cm−3 or higher). In this situation, more widespread shallow clouds with greater amount of cloud water form in the valley and foothills, which changes the local circulation through more latent heat release that transports more moisture to the windward slope, leading to much more invigorated mixed-phase clouds over the mountains that produce higher amounts of snow precipitation. Increasing INPs leads to decreased riming and mixed-phase fraction in the CMOC but has the opposite effects in the WMOC, as a result of liquid-limited and ice-limited conditions, respectively. However, it increases precipitation in both cases due to an increase of deposition for the CMOC but enhanced riming and deposition in the WMOC. Increasing INPs dramatically reduces supercooled water content and increases the cloud glaciation temperature, while increasing CCN has the opposite effects with much smaller significance.

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

2017 ◽  
Vol 17 (24) ◽  
pp. 15199-15224 ◽  
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.

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

2017 ◽  
Vol 17 (5) ◽  
pp. 3637-3658 ◽  
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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