AS3.14
Orals: Tue, 25 Apr | Room 0.11/12
This presentation will be an invitation to think differently about the possible oxidation pathways occurring in secondary organic aerosols.
Despite the importance of aerosols in atmospheric chemistry, climate and air pollution, our ability to assess their impact on atmospheric physics and chemistry is still limited due to insufficient understanding of many processes associated with the sources of particles, their chemical composition and morphology, and evolution of their composition and properties during their atmospheric lifetime. Indeed, atmospheric aerosols can be viewed as a complex conglomerate of thousands of chemical compounds forming a system that evolves in the atmosphere by chemical and dynamical processing including chemical interaction with oxidants and sunlight.
A significant body of literature on photo-induced charge or energy transfer in organic molecules from other fields of science (biochemistry and water waste treatment) exists. Such organic molecules are aromatics, substituted carbonyls and/or nitrogen containing compounds – all ubiquitous in tropospheric aerosols. Multiphase processes have also been shown to produce light absorbing compounds in the particle phase. The formation of such light absorbing species could induce new photochemical processes within the aerosol particles and/or at the gas/particle interface. Therefore, while bulk phase aquatic photochemistry has recognized several of these processes that accelerate degradation of dissolved organic matter, only little is known about such processes in/on atmospheric particles.
This presentation will discuss photosensitization in the troposphere as having a significant role in SOA formation and ageing as studied by means of laser transient absorption spectroscopy, flow tube and simulation chamber experiments, all coupled to advanced analytical techniques. We will provide kinetic and mechanistic information on how photosensitization may introduce new chemical pathways, so far unconsidered, which can impact both the chemical composition of the atmosphere and might thus contribute to close the current SOA underestimation.
How to cite: George, C.: Photosensitization is in the air and impacts the multiphase on oxidation capacity, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-2093, https://doi.org/10.5194/egusphere-egu23-2093, 2023.
Aerosols have a net cooling effect in our atmosphere, mainly due to their ability to act as cloud condensation nuclei (CCN) and to reflect incoming solar radiation [1]. In aerosols the surface is particularly important as it is the site for many processes which are central to cloud formation, in particular evaporation and condensation. Aerosol surfaces contain a wide variety of organic and inorganic chemical compounds. Understanding the resulting surface structure and composition is a necessary first step in gaining a better understanding of the role aerosols play in the atmosphere.
In particular, the surface composition affects the hygroscopicity of the particle and thereby its ability to act as a CCN [2]. While the surface propensity of individual compounds has been studied widely, much less is known about cooperative effects in more complex mixed systems [3]. Here we use sum-frequency-generation (SFG) spectroscopy in conjunction with surface tension data to study whether surface competition or cooperative enhancement can be observed in mixed solutions of halides and acids or alcohols of different chain length.
We find that in certain cases the presence of different ions can affect the surface structure in a unique way. However, these effects are not systematic and appear to depend on the specific nature of the interaction between the ions and the respective organic compound. This further highlights that the surface structure of mixed systems cannot be extrapolated from studies of simple solutions.
[1] IPCC. Climate Change 2013: The Physical Science Basis. [2] P. Zieger et al., Nat. Commun. 2017, 8, 15883. [3] M.T. Lee et al., Phys. Chem. Chem. Phys. 2019, 21, 8418
How to cite: Saak, C. M., Mika, S. M., and Backus, E. H. G.: Ion specific Interactions and Surface Enrichment on Mixed Aerosol Surfaces, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-14850, https://doi.org/10.5194/egusphere-egu23-14850, 2023.
Effect of pH on pyruvic acid in bulk and at the air/liquid interface
Veronika Wank and Ellen H. G. Backus
University of Vienna, Faculty of Chemistry, Department of Physical Chemistry,Währinger Straße 42, 1090 Vienna, Austria
Abstract:
Pyruvic acid, known as a relevant carboxylic acid for plant metabolic processes is also a contributor to the formation of secondary organic aerosols (SOA) and thus of great importance for the atmospheric cycle, especially in aerosols. At the interface, the behavior of relevant atmospheric molecules in aerosols is a major topic, as the surface is one of the first areas where chemical processes take place and thus determines the main reactivity of the aerosol. For acidic molecules, the acid/base behavior, especially at the interface, is relevant for understanding the chemical interaction of organic matter in atmospheric aerosols, where reaction rates and product distributions change due to different pH conditions, e.g. chemical processing and molecule transport.
Since the pH of aqueous aerosols can vary widely, it is particularly important to understand changes in the surface structure due to the resulting (de)protonation reactions.
This encourages us to take a closer look at the interfacial region of pyruvic acid in aqueous solution by using a complex surface-specific spectroscopic technique, so called sum frequency generation spectroscopy (SFG). For comparison, infrared bulk measurements utilizing ATR spectroscopy were completed. By combining ATR and SFG, the protonation state of pyruvic acid for bulk and interface was determined by probing the vibrational signatures of the carboxylic acid groups.
Our results show that pyruvic acid at the water interface is more alkaline than in the bulk, which indicates that the carboxylic acid group deprotonates at a higher pH value at the surface than in the bulk. It is also evident from the SFG spectra that at lower pH the water molecules on the surface are displaced by PA molecules, whereas at higher pH the water molecules return to the surface and the PA molecules tend to go into the bulk.
This implies that the protonation state of carboxylic acids like PA can thus affect the molecular orientation, conformation and function of molecules on aqueous surfaces, which likely has a significant impact on the chemical processes taking place at the aerosol surface in the atmosphere.
How to cite: Wank, V.: Effect of pH on pyruvic acid in bulk and at the air/liquid interface, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-15680, https://doi.org/10.5194/egusphere-egu23-15680, 2023.
The formation and impact of ice crystals in clouds remain a challenge to understand and thus to be predicted in models. In recent years, measurements of ice-nucleating particles (INPs) in ambient air have become more frequent, using well-established and novel techniques such as mobile cloud chambers and filter-based freezing assays. To assure that these techniques are working as intended, validation and intercomparison measurements are required. This is especially relevant due to ongoing efforts for the establishment of INP monitoring networks at the European level (ACTRIS; Aerosol, Clouds and Trace Gases Research Infrastructure) and in the United States (ARM; Atmospheric Radiation Measurement).
Here we present results from PICNIC (The Puy de Dôme ICe Nucleation Intercomparison Campaign), conducted at a mountain site in Central France (1465 m a.s.l.) in October 2018. INP concentrations relevant in the mixed-phase cloud regime were determined using three online INP techniques (Colorado State University-Continuous Flow Diffusion Chamber, CSU-CFDC; Spectrometer for Ice Nuclei, SPIN; Portable Ice Nucleation Experiments, PINE) and seven filter-based offline freezing devices (FRankfurt Ice Nuclei Deposition FreezinG Experiment, FRIDGE; Ice Nucleation Droplet Array INDA; Ice Nucleation Spectrometer of the Karlsruhe Institute of Technology, INSEKT; CSU Ice Spectrometer, IS; Leipzig Ice Nucleation Array, LINA; LED based Ice Nucleation Detection Apparatus LINDA; Micro-Orifice Uniform Deposit Impactor–Droplet Freezing Technique, MOUDI-DFT). The campaign focused on INP concentration measurements performed at the same time and at comparable nucleation temperatures, which is why filter sampling for offline techniques was started and stopped simultaneously, and online INP measurements were conducted at similar thermodynamic conditions. While the ice chambers yielded reasonable agreements within factors of 2 to 5, with lower concentrations found by SPIN, a systematic deviation between filter samples collected directly outside on the station’s rooftop and those sampled downstream from a whole air inlet is observed. A potential loss of larger aerosol particles via the inlet and an impact of the disaggregation of larger aerosol particles in solution might cause these differences, which needs to be investigated in future studies.
How to cite: Lacher, L. and Freney, E. and the PICNIC team: The Puy de Dôme Ice Nucleation Intercomparison Campaign, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-8694, https://doi.org/10.5194/egusphere-egu23-8694, 2023.
Pollen belong to a subset of atmospheric aerosol particles that enable the glaciation of supercooled liquid water, which is present in clouds down to an ambient temperature of -38°C. While the ice nucleating properties of pollen are widely researched in laboratory studies, it is challenging to evaluate their effect on clouds in observations at a large scale. Using a combination of ground-based measurements of pollen concentration and satellite observations of cloud properties during springtime, we show that the ice nucleating properties of pollen promote the glaciation of supercooled liquid water. We further establish the link between the pollen-induced increase in cloud ice to a higher precipitation frequency. In light of anthropogenic climate change, the extended and strengthened pollen season and alterations in biodiversity can, therefore, introduce a localized climate forcing and a modification of the precipitation frequency and intensity, especially during springtime.
How to cite: Kretzschmar, J., Wirth, C., Pöhlker, M., Stratmann, F., Wex, H., and Quaas, J.: Enhancement of cloud glaciation and rain frequency by airborne pollen, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11479, https://doi.org/10.5194/egusphere-egu23-11479, 2023.
Primary biological aerosol particles (PBAPs) are emitted from Earth’s biosphere, including pollen, fungal spores, virus, bacteria, and plant debris. PBAPs are linked to adverse health effects and have the potential to influence ice nucleation at warmer temperatures. Anemophilous (or wind-driven) pollen is one type of PBAP, and the emitted pollen grains can rupture under high humidity to form smaller sub-pollen particles (SPP). Both pollen and SPP can be lifted to the upper troposphere under convective conditions, readily take up water and serve as cloud condensation nuclei (CCN) and ice nucleating particles (INPs), and therefore impact cloud formation and reflectivity. Although these biological aerosol have proven to be effective INPs in previous studies, they are typically not included in emission inventories. Therefore, it is difficult to quantify their effects on cloud formation and local climate.
Here, we include the emission and rupture of pollen in WRF-Chem simulations and investigate the impacts of pollen and SPP on both warm and ice clouds in the United States South Great Plains (SGP) from April 11-20, 2013, a period with high pollen emission and convective events. We update the Morrison microphysics scheme inside WRF-Chem using aerosol-aware INP parameterizations, considering different freezing mechanisms including heterogeneous freezing (immersion, contact, and deposition freezing) and homogeneous freezing. We further incorporate heterogeneous ice nucleation from pollen and SPP in the model to evaluate pollen effects on ice cloud formation. The corresponding pollen and SPP INP parameterizations are obtained by laboratory experiments that indicate pollen grains are more efficient INPs than SPP and could contribute to ice cloud formation. The model simulation results are evaluated using observational data from Atmospheric Radiation Measurement (ARM) SGP sites. We conducted a suite of sensitivity tests to examine the impacts of pollen and SPP on one convective event (April 17-18, 2013), and compare the newly developed pollen and SPP INP parameterizations with those developed in previous literature. Our results highlight that the addition of PBAPs such as pollen could shift the convective event onset timing and vertical structure.
How to cite: Zhang, Y., Subba, T., Hendrickson, B. N., Brooks, S. D., and Steiner, A. L.: Simulating the impacts of pollen on cloud formation by heterogeneous ice nucleation , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-10480, https://doi.org/10.5194/egusphere-egu23-10480, 2023.
With raising temperatures in the Arctic, the extent of sea ice is decreasing dramatically resulting in a larger fraction of the Arctic ocean surface being exposed to the atmosphere. Therefore, the ice-free ocean and in particular the sea surface microlayer (SML), which represents the upper 1 mm of the water column is becoming of increasing interest as a source of bioaerosols with ice nucleating properties. These biological ice nucleating particles (INPs) can be aerosolized by wave breaking and bubble bursting. In the atmosphere, they may trigger the freezing of cloud droplets and thus affect the lifetime of clouds as well as their radiative properties. Recent studies proposed a link between biological ice nucleating aerosols in the Arctic sea water and phytoplanktonic blooms.
Thus, we examined the concentration and characteristics of INPs in both, the sea bulk water, and the surface microlayer for two locations in southwest Greenland throughout a phytoplankton bloom. Further, we investigated possible links between INP concentrations in the sea water, the abundance and community composition of bacteria and algae, as well as the phytoplanktonic growth season derived from satellite data and in-situ chlorophyll concentrations. Preliminary results will be presented.
How to cite: Wieber, C., Jensen, L. Z., A. Ferreira, A. S., Vergeynst, L., Finster, K., and Šantl-Temkiv, T.: Dynamics of biological ice nucleating particles during a phytoplanktonic bloom in the Arctic , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11673, https://doi.org/10.5194/egusphere-egu23-11673, 2023.
Soot particles emitted by aircraft in the troposphere can serve as ice nucleating particles (INPs) in the cirrus regime, which can compete with natural cirrus formation by homogeneous freezing of solution droplets and influence cirrus cloudiness and microphysics. Soot particles show varying ice nucleation (IN) abilities, depending on the particle properties that regulate the IN pathway and effectiveness. Pore condensation and freezing (PCF) is an important pathway for soot IN, which first forms supercooled water in soot mesopores (2-50 nm width) via capillary condensation and then freezes below homogeneous nucleation temperature. Soot PCF shows dependence on the particle mesopore abundance and soot-water contact angle (θ) according to the Kelvin equation. However, the relative importance of θ and mesopore abundance in soot PCF has not been disentangled.
In this study, the θ of organic-lean soot was changed after exposure to a high (20 ppmv) and a low (2 ppmv) O3 concentration condition to mimic a long- (~20 h) and short-term (~2 h) aging in the real atmosphere respectively, without changing the soot mesopore abundance. Secondary organic formation was avoided by establishing a volatile free experimental environment. The IN activities of both fresh and O3-aged soot particles, with aggregate size of 200 and 400 nm, were tested by the Horizontal Ice Nucleation Chamber (HINC) under cirrus cloud conditions for T≤233 K. The size and mass of soot particles for IN experiments were also monitored. The θ of bulk samples exposed to the same O3 concentration conditions (20, 2 or 0 ppmv) as used for IN experiments was directly measured by the Sessile-drop method. The O3-aging effects on soot chemical composition, soot-water interaction ability and porosity were also characterized by using thermogravimetric analysis (TGA), dynamic vapor sorption (DVS) and N2 Brunauer–Emmett–Teller (BET) techniques, respectively.
The adsorption of O3 onto soot particles was demonstrated by a particle mass increase after O3-exposure. The unchanged chemical functional group abundance and increased water-uptake ability at low relative humidity (RH) conditions after O3-aging implies that the soot-water interaction increase is likely due to direct O3-H2O binding rather than surface oxidation, which explains the θ decrease of O3-aged soot. Compared to unaged soot of the same size, a higher O3 exposure level leads to a larger decrease in soot-water θ and a more significant IN enhancement for O3-aged soot. However, O3-aged soot presents unchanged pore size distribution and particle size, irrespective of O3 exposure concentration. According to the Kelvin equation, the θ decrease induced by O3-aging can alone contribute to the IN enhancement of soot, given that the lower the θ is, the lower the RH condition required to trigger capillary condensation. In conclusion, this study highlights the single importance of θ in soot PCF in the cirrus regime, by modifying the soot-water θ through O3-aging while remaining the porosity.
How to cite: Gao, K. and Kanji, Z.: The importance of soot-water contact angle in soot ice nucleation ability in the cirrus regime, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-138, https://doi.org/10.5194/egusphere-egu23-138, 2023.
Mineral dust is the main responsible ice nucleating particle (INP) type for mixed-phase clouds and has an influence over regions far from the dust source. Parameterizations of the dust ice nucleation (IN) ability used in models are normally obtained from experimental characterization of dust collected from the surface at origin (Ullrich et al., 2017). However, IN properties of long-range transported dust may differ from the dust at origin due to different mineralogy and physical or chemical transformations along the transport route. Here we present preliminary results of ice nucleation properties of Saharan dust transported to Spain and Finland in the temperature range relevant for mixed-phase cloud formation.
In this work, the IN ability in immersion mode is evaluated using an Mk-1 droplet-freezing cold stage (Sikora Scientific Instrumentation). The drop-freezing assays are performed by depositing a set of dust-containing droplets (1 μL) onto a hydrophobic glass that rests atop the cold stage, whose temperature can be varied at a specific cooling rate. A high-resolution camera captures images tracking the freezing events, while the temperature is decreased. Dilutions of the original suspensions are prepared to explore the colder temperature range. Heat treatments are applied to the samples to investigate the contribution of the sample’s biological-origin components to its ice nucleation ability. The BET surface area is measured for selected samples.
This work was supported by the Academy of Finland Flagship ACCC (grant no. 337552) and MEDICEN project (grant no. 345125).
Ullrich, R. et al. (2017). A New Ice Nucleation Active Site Parameterization for Desert Dust and Soot J. Atmos. Sci., 74, 699-717.
How to cite: Piedehierro, A. A., Welti, A., Mustonen, L., Meinander, O., Viisanen, Y., and Laaksonen, A.: Long-range transport effect on the ice nucleation properties of Saharan dust, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-12590, https://doi.org/10.5194/egusphere-egu23-12590, 2023.
Posters on site: Wed, 26 Apr, 08:30–10:15 | Hall X5
Solar simulators are indispensable tools and are usually linked to industrial applications, e.g. for determining the precise characteristics of solar cells. In photochemistry, usually UV light is used to stimulate the photo-interactions without particular attention to the spectral distribution. However, the spectral distribution has a non-negligible effect on the photoreaction pathways. To address photochemistry under atmospheric conditions, it is necessary to use an irradiation source that emits light equivalent to the solar light. Solar simulator based on LED technology is the best candidate for irradiating natural photo-interactive substances at specific wavelength and intensity. We have devolved a homemade compact light source that is based on LED technology, and emits light with wavelength starts from 275 nm with tuneable intensity, selectable wavelength, homogenous illumination, compact size and light weight. In this presentation we present the design and characteristics of our homemade solar simulator and demonstrate potential application in atmospheric surface-chemistry.
How to cite: Abdelmonem, A. and Fawey, M. H.: Atmospheric Surface-Science Solar Simulator: An artificial solar irradiator for atmospheric photochemistry, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-12324, https://doi.org/10.5194/egusphere-egu23-12324, 2023.
This paper is going to discuss the volcanic eruptions in several different locations, most in the Northern and Southern Hemisphere, and how they will affect the wheater near and far locations.
There is much evidence that eruptions are one of the biggest causes of climate change. A historical number of events will show for each volcanic eruption a consequent disturbance, most at the rainfall and storms. Gas emissions such as CO2 and SO2 are heavy in the troposphere, sometimes reaching the mesosphere. Those circumstances alternatively affect also the temperature at the Earth’s surface. The volcanic eruptions must explain sudden events in the weather around the world.
The mechanism involved in those events’ transportation among the several atmospheric layers is also discussed.
How to cite: Hagen, M.: Volcanic Activity, possible climate change consequences , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-1914, https://doi.org/10.5194/egusphere-egu23-1914, 2023.
We report on the addition of 50 years of literature data to the Ice Nucleation DataBase (INDB) created for the EU FP7 BACCHUS project (https://www.bacchus-env.eu/in/). The database is intended to become a tool for the Ice Nucleation community to facilitate finding ice nucleating particle (INP) concentration data collected at specific locations and times. The INDB can be used for comparison reviews, to investigate temporal changes in INP concentrations, identify regions of interest, to inform the planning of future observations, and to facilitate data provision for modelling studies. Worldwide data from more than 170 publications between 1949 to 2000 were digitised and added to the INDB, and more than 130 additional publications have been identified and will be utilized to extend the compilation into 2020. Here we provide an overview of the digitised historical datasets, the times, locations, and experimental conditions under which INP were measured. Exemplary insights from the INDB are discussed by comparing ambient temperature spectra pre and post 1970 in different geographic regions.
How to cite: Welti, A., Thomson, E. S., Schrod, J., Ickes, L., David, R. O., Dong, Z., and Kanji, Z. A.: Overview of ambient ice nucleation measurements from 1949 – 2000, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-1458, https://doi.org/10.5194/egusphere-egu23-1458, 2023.
Ice nucleating particles (INPs) are a rare but important type of atmospheric aerosol particles, contributed mostly by mineral dust particles and by biogenic macromolecules expressed by a range of different microorganisms. INPs’ ability to nucleate ice in cloud droplets already far above their homogeneous freezing temperature (at ~ -38°C) influences for instance cloud radiative processes and precipitation formation.
Despite a recent surge of research on INPs, neither are all important sources of atmospheric INP sufficiently known, nor their atmospheric abundance which varies with location and season.
Here we examine the heat sensitivity of some types of INP of biogenic origin by exposing them to a range of different heating temperatures (60°C, 85°C, and 90°C) for one hour. The heating is expected to destroy proteinaceous ice active macromolecules. The ice activity of different samples was examined before and after heating.
Examined samples included birch pollen (Betula pendula), fungi (Mortierella alpina, Fusarium acuminatum), the bacteria Pseudomonas syringae (from a commercially available SNOMAX sample) and aspen leaves (from Populus tremuloides) which had been sampled and freeze-dried decades ago. We compare their heat sensitivity to that of INPs from airborne aerosol samples collected on filters in summer months at Villum Research Station (VRS) in North Greenland, which were exposed to the same heating procedure.
For samples from F. acuminatum and P. syringae, a continuing decrease in ice activity (expressed as INP per sample mass) was observed for each of the heating steps. The decrease was larger than one order of magnitude for each heating step across the examined temperature range (roughly -5°C to -25°C). For the B. pendula sample, highly ice active macromolecules inducing ice nucleation at > -10°C were already destroyed by heating to 60°C, while the signal below -15°C was changed much less by any of the heating steps. The M. alpina sample showed no change in ice activity after heating to 60°C, but a strong decrease across the examined temperature range after heating further to 85°C, and some additional decrease (roughly one order of magnitude) after heating to 90°C. The aspen leave samples showed no noticeable reaction to heating at freezing temperatures below -15°C, but behaved similar to the M. alpina sample at -10°C.
Interestingly, for freezing temperatures > -10°C, INP concentrations of VRS summer samples also showed no or only a small decrease in ice activity upon heating to 60°C, similar as the M. alpina and aspen leave samples. Also similar to these two, VRS samples showed a very pronounced decrease upon heating to 85°C and some further decrease upon heating to 90°C. This is interesting in the light that recent research suggested that M. alpina, together with the bacteria species Pantoea ananatis, are likely sources of the INPs present in a aspen leave sample of the same batch as the one examined here. Combining these findings, we speculate that M. alpina may be of considerable importance as terrestrially sourced atmospheric INPs for regions even including the summer Arctic.
How to cite: Wex, H., Gundlach, J., Backes, A. T., Fröhlich-Nowoisky, J., Sze, K. C. H., Massling, A., Skov, H., Schnell, R., and Hartmann, S.: Learning from the temperature sensitivity of biogenic and Arctic ice nucleating particles, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-3297, https://doi.org/10.5194/egusphere-egu23-3297, 2023.
Scots pine (Pinus sylvestris) is the most widespread pine species in the world. It is a major tree species found in the northern hemisphere and in large parts of the boreal forest. In recent studies, birch trees, another notable species in the boreal forest, have been identified as an important emission source of ice-nucleating macromolecules (INMs). The INMs were found in pollen1 and all over the tree’s tissue (e.g., branch wood, bark, petioles, and leaves)2,3. Similarly, Scots pine pollen were found to be ice nucleation active, but until now, no further investigation of INMs from other tissue types has been conducted.
In this laboratory and field study, we collected samples from six different Scots pine trees in urban parks in Vienna, Austria. We investigated the distribution of INMs among three different tissue types, namely bark, branch wood, and needles, by extracting them from the milled sample (as a bulk sample) and the surface of the intact tissue and measuring ice nucleation activity in immersion freezing mode. We aimed to quantify the overall INM content of this species and assume it is independent of the growing region, as previously reported for birch trees, allowing us to extrapolate our results to the vast locations where Scots pines are found. In addition, we investigated the ability of rain events to wash the INMs off trees in a field study.
We found INMs in all samples with freezing onset temperatures ranging from -16°C to -29°C. The bulk samples showed INM concentrations ranging from 105 to 109 per mg dry weight active at -25°C and higher. In surface extracts from the intact tissue, we found concentrations from 105 to 108 INMs per cm2 of the extracted surface. Most importantly, we found all rain samples to contain INMs with similar freezing onset temperatures to the lab extracts.
On the basis of our results, we estimate that one square meter of Scots pine stand has the potential to release about 109 to 1012 INMs active at -25°C or higher. This estimation reveals pine trees as a massive reservoir of INMs. Boreal forests containing large numbers of birch and pine trees must be considered an essential source of atmospheric INMs. We propose Scots pine as an important emission source of INMs, nucleating ice in immersion freezing mode at moderate supercooled temperatures and thereby impacting the microphysics of mixed-phase clouds.
(1) Pummer, B. G.; Bauer, H.; Bernardi, J.; Bleicher, S.; Grothe, H. Suspendable Macromolecules Are Responsible for Ice Nucleation Activity of Birch and Conifer Pollen. Atmospheric Chemistry and Physics 2012, 12 (5). https://doi.org/10.5194/acp-12-2541-2012.
(2) Felgitsch, L.; Baloh, P.; Burkart, J.; Mayr, M.; Momken, M. E.; Seifried, T. M.; Winkler, P.; Schmale, D. G.; Grothe, H. Birch Leaves and Branches as a Source of Ice-Nucleating Macromolecules. Atmospheric Chemistry and Physics 2018, 18 (21). https://doi.org/10.5194/acp-18-16063-2018.
(3) Seifried, T. M.; Bieber, P.; Felgitsch, L.; Vlasich, J.; Reyzek, F.; Schmale, D. G.; Grothe, H. Surfaces of Silver Birch (Betula Pendula) Are Sources of Biological Ice Nuclei: In Vivo and in Situ Investigations. Biogeosciences 2020, 17 (22). https://doi.org/10.5194/bg-17-5655-2020.
How to cite: Reyzek, F., Seifreid, T. M., Bieber, P., and Grothe, H.: Scots pines (Pinus sylvestris) as sources of biological ice-nucleating macromolecules (INMs), EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-2067, https://doi.org/10.5194/egusphere-egu23-2067, 2023.
Ice-nucleating particles (or INP) play an important role in controlling cloud radiative properties and lifetimes. Therefore, understanding the sources and mechanisms of ice formation in clouds is vital for understanding their impact on cloud radiative feedback. Agricultural dust contributes 25% of global dust emissions and has been shown to nucleate ice at temperatures up to -6°C. This high nucleating ability of agricultural soils suggests that they may be an essential source of INPs on regional or global scales. Many organic components, which have been shown to be important for ice nucleation in soils, have surface active properties that may enhance the ice-nucleating ability of the soil. In this work, lignin was used as a reference for investigating surfactant macromolecules as a potential component of ice nucleation. Lignin solutions showed high ice-nucleating activity in line with decreases in surface tension. We contrasted our observations of lignin with observations from soil extractions from samples taken in the field. Preliminary results suggest little correlation between surface tension measurements and the ice-nucleating activity of extracted soil samples. The presence of a correlation between ice-nucleating and surface activity in soil components such as lignin, but the absence of this correlation in complete soil samples suggests that surfactants can be important ice-nucleating macromolecules, but that highly active soil samples do not necessarily reduce the surface tension at the water-air interface.
How to cite: Thompson, K., Link, N., Murray, B., and Borduas-Dedekind, N.: The relationship between surface tension and atmospheric ice-nucleating activity of agricultural soil, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-7153, https://doi.org/10.5194/egusphere-egu23-7153, 2023.
Ice nucleation in the upper troposphere occurs either homogeneously or heterogeneously. For heterogeneous nucleation, mineral dust is known as an efficient ice nucleating particle (INP) or an aerosol that has the ability to nucleate ice. The global abundance of these mineral particles is poorly understood and thus it often limits accurate representation in model studies. The aim of this work is to simulate ice nucleation with deposition nucleation and compare the results to in-situ measurements.
The simulations are run with large-eddy model UCLALES-SALSA by applying multiple existing deposition nucleation parametrizations for mineral dust. These parametrizations are either based on laboratory measurements or classical nucleation theory. For the simulation setup, ECMWF reanalysis and campaign data from NASA MACPEX are used to create suitable conditions for in-situ cirrus formation. The simulations are based on the 16th of April 2011 science flight which was flown into a synoptic cirrus that formed over Northern Mexico to the Gulf of Mexico.
The simulated ice with all used parametrizations on average produced concentrations within two orders of magnitude of what was measured with onboard instruments. The main limiting factor for ice number concentration in the simulations is mineral dust concentration since every ice crystal formed only on mineral dust particles. The ice number concentration in measurements exceeded the mineral dust concentration which indicates that other INPs or freezing mechanisms might be involved in this scenario.
Further simulations are required to grasp a better understanding of the role of mineral dust in the cirrus cloud formation.
Acknowledgements
This work was supported by the Academy of Finland Flagship ACCC (grant no. 337552) and
MEDICEN project (grant no. 345125).
How to cite: Juurikkala, K., Laaksonen, A., and Welti, A.: Simulation of deposition nucleation using ice nucleation parametrizations and comparison of model results to measured cirrus cloud properties, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-9420, https://doi.org/10.5194/egusphere-egu23-9420, 2023.
Ice nucleating particles (INPs) are particles in the atmosphere that are able to initiate the freezing of water droplets, a process known as ice nucleation. INPs are important to study because they play a crucial role in many atmospheric processes, including the formation of clouds, precipitation, and the radiative properties of clouds. For example, INPs can influence the concentration, size, and shape of ice crystals in clouds, which can in turn affect the reflectivity and lifetime of the clouds. This can have significant impacts on Earth's radiative balance and climate. The most relevant process of ice crystal formation in mixed-phase clouds (MPC) is by immersion freezing (Ansmann et al., 2009). Immersion freezing takes place when an INP is immersed in a water droplet and freezing is triggered on the particle's surface. In this research, we present a series of INP concentration measurements obtained using a novel assay under development at the Finnish Meteorological Institute in Helsinki. The focus of our research is to evaluate the consistency and replicability of these measurements. To determine the contribution of different aerosols to the INP spectrum at different temperatures, we collect atmospheric particles onto membrane filters and analyze the concentration of INPs in a laboratory freezing experiment. In this experiment, we produce an aqueous solution with collected atmospheric particles and monitor identical aliquots of the aqueous solution while they are cooled until freezing. Finally, using the frozen fraction of aliquots at a given temperature, the volume of each aliquot, and the sample's air volume, the cumulative number of INPs in the given sample at each temperature is calculated following (Vali, 2019). Three automatic samplers were run in parallel to collect particles onto the membrane filters using different sampling schemes. For example, collecting daily samples with three different sampling flows. With these measurements, we will analyze the influence of the sampled air volume, air flow, and sampling duration on the INP concentration measurements.
References
Ansmann, A. et al. (2009) Evolution of the ice phase in tropical altocumulus: SAMUM lidar observations over Cape Verde Atmosphere, 9(9), 357
Vali, G., (2019). Revisiting the differential freezing nucleus spectra derived from drop-freezing experiments: Methods of calculation, applications, and confidence limits. Atmos. Meas. Tech., 12(2), 1219-1231. https://doi.org/10.5194/amt-12-1219-2019
How to cite: Perez Fogwill, G., Welti, A., Servomaa, H., Timo, A., Piedehierro, A., Leskinen, A., Komppula, M., Hyvärinen, A., and Asmi, E.: Ice nucleating particle measurement at Helsinki, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11748, https://doi.org/10.5194/egusphere-egu23-11748, 2023.
Deep convective clouds produce severe weather and their reflective anvil tops play a role in climate feedbacks. As mixed-phase clouds, they can be greatly affected by the concentration and activity of ice-nucleating particles (INPs) (Hawker et al., 2021). INP are aerosol that initiate primary ice production in mixed-phase clouds and in-situ measurements of their concentrations are scarce. Here we present analysis of INP data from aerosol filter sampling done on the FAAM aircraft the DCMEX (Deep Convective Microphysics Experiment) field campaign in New Mexico, USA, during July-August 2022. The project aims to improve the representation in climate models of microphysical processes in deep convective clouds. This location was selected because clouds formed and developed almost daily in the same location over the Magdalena Mountains during the summer monsoon season, which allowed observation of the first primary ice particles and also repeated sampling of INP in the air that that flowed into the cloud bases.
Offline INP sampling consisted of filter sampling using the FAAM Bae-146 aircraft platform along circuits around the Magdalena Mountains (16 flights). Filters were analysed during the campaign for INP using microlitre droplet freezing assays and then combined with total air flow to determine INP concentrations. We found that airborne-derived INP concentrations were higher than the upper range of past observations from continental precipitation samples (Petters and Wright, 2015) but within those of primary ice-crystal concentrations observed in clouds (Cooper, 1986). Airborne sampling runs typically saw 1-10 L-1 at -15 °C with INP active above -10 °C and up to -5 °C frequently observed both below cloud base (>200 m above ground level) and also through a substantial portion of the free troposphere, typically to up to an altitude of 4,000-6,000 m (2,500-4,500m above ground level). INP concentrations decreased above this level by an order of magnitude. INP concentrations were normalised to aerosol surface area measurements derived from aircraft Passive Cavity Aerosol Spectrometer Probe data to derive spectra for number of active sites per aerosol surface area (ns(T)). This revealed that the ice-nucleating activity of the aerosol consistently was higher than that described by parameterisations for desert dust, inferring a biological origin for the INP population.
Further analysis including relating INP concentrations to aerosol composition and particle size distribution, comparison of INP number to cloud ice-crystal concentration are in progress to ultimately determine relationships between primary production via INP and ice concentrations in cloud. This will help us better understand the properties and development of and ultimately improve modelling of convective clouds.
References
Cooper, W. A.: Ice Initiation in Natural Clouds, in: Precipitation Enhancement—A Scientific Challenge, American Meteorological Society, 29-32, 1986.
Hawker, R. E., Miltenberger, A. K., Wilkinson, J. M., Hill, A. A., Shipway, B. J., Cui, Z., Cotton, R. J., Carslaw, K. S., Field, P. R., and Murray, B. J.: The temperature dependence of ice-nucleating particle concentrations affects the radiative properties of tropical convective cloud systems, Atmos. Chem. Phys., 21, 5439-5461, 10.5194/acp-21-5439-2021, 2021.
Petters, M. D., and Wright, T. P.: Revisiting ice nucleation from precipitation samples, Geophysical Research Letters, 42, 8758-8766,
How to cite: Daily, M., Robinson, J., McQuaid, J., Finney, D., Blyth, A., and Murray, B.: Observations of ice-nucleating particles during deep convective cloud development in New Mexico, USA, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-15693, https://doi.org/10.5194/egusphere-egu23-15693, 2023.
Two approaches of heterogeneous ice nucleation have been proposed in previous studies. These are the singular approach (time-independent), and time-dependent approach. The present study numerically analyses the effect from the time-dependent approach of ice nucleation in deep convective, orographic, and supercooled stratiform clouds, sampled by aircraft. It is predicted that in all the simulated clouds, the singular approximation is a good representative of heterogeneous ice nucleation. At levels warmer than -36oC, the inclusion of time-dependence is predicted to form only about 10 % of the total ice, whereas secondary ice processes (the Hallett-Mossop process and fragmentation during ice-ice collisions, raindrop-freezing, and sublimation) form about 90 % of the total ice at these levels. The present study uses the ‘Aerosol-Cloud’ (AC) model. The AC represents microphysical species as rain, cloud-ice (‘crystal’), snow, and graupel/hail and treats cloud properties with a hybrid spectral bin, and two-moment bulk microphysics schemes. Also, radiative effects from ice nucleating particles on the simulated deep convective and orographic clouds will be discussed.
How to cite: Waman, D., Patade, S., Jadav, A., and Phillips, V.: Singular versus Time-dependent Approach of Heterogeneous Ice Nucleation and Secondary Ice Production in Contrasting Clouds Simulated Numerically, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-1834, https://doi.org/10.5194/egusphere-egu23-1834, 2023.
Clouds between -42°C and 0°C may be in a phase of pure-liquid, pure-ice, or a mixture of both. The cloud’s phase affects its radiative effect. However, the cloud phase variability is poorly understood, resulting in a high uncertainty in the climate warming projected by models. Passive retrievals from space have the potential for resolving the temporal variability of cloud phase globally and could help to better understand the drivers of cloud glaciation. In our study, we show that daily passive retrievals of cloud phase are highly unreliable, but the monthly phase frequency for thick stratiform clouds offers a reliable constrain for cloud phase variability.
We find that for both the daily cloud phase and the monthly phase frequency, the agreement among different retrieval algorithms increase for thick stratiform clouds. Moreover, for these clouds, the hemispheric and seasonal contrast of cloud phase agrees better with previous estimations from active retrievals. Using thick stratiform clouds observed from space during 35 years, we offer for the first time an estimation of the seasonal cloud phase contrast resolved globally. This estimation will help increase our understanding of the yet poorly-known drivers of cloud glaciation. Moreover, we offer a previously missing benchmark for climate models to constrain the physical processes behind cloud glaciation in order to reduce the associated uncertainty in climate projections.
How to cite: Villanueva, D.: Retrieving global cloud top phase patterns: The reliability of spaceborne retrievals, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-2441, https://doi.org/10.5194/egusphere-egu23-2441, 2023.
Mineral dust acts as ice-nucleating particles (INPs) to alter cloud microphysical properties and thus further impact cloud radiative effects (CRE). As the third pole of the world, the Tibetan plateau (TP) is one of the most sensitive regions to climate change along with the Arctic and Antarctic, warming twice as fast as the global average, affecting glacial melt, hydroelectric power, and water supply for billions of people. Several important Asian deserts are distributed around the TP, and large-scale seasonal dust storms lift and sweep this region every spring. However, the effects of these mineral INPs on ice formation and radiation budgets of clouds over the TP are not well understood.
In this study, we investigated the immersion mode INP properties of 47 snowmelt samples collected from five glaciers throughout the TP using droplet freezing techniques, identified the dominative factor affecting INP concentration via particle chemistry and morphology analyses and air mass trajectory calculation, and discussed their implications for the cloud microphysical properties by ten-year satellite data (Moderate Resolution Imaging Spectroradiometer, MODIS) and climate reanalysis (ECMWF Reanalysis V5, ERA5). A total of 47 snowmelt samples were collected at five different glaciers over the whole TP in the summer of 2020: Laohugou, LHG (39.4°N, 96.6°E, 4990 m above sea level (masl), 10 samples); Tianshan, TS (43.1°N, 86.8°E, 4070 masl, 12 samples); Dongkemadi, DKMD (33.1°N, 90.1°E, 5708 mas, 10 samples); Ali, AL (32.8°N, 80.9°E, 5967 masl, 10 samples); Zhufeng (Mt. Everest), ZF (35.7°N, 94.2°E, 6525 masl, 5 samples). The average INP concentrations were 1.255, 0.646, 0.257, 0.103, and 0.016 L-1 air at -20℃ for LHG, TS, DKMD, AL, and ZF, respectively, showing a spatial distribution with higher INP concentrations in the north and lower INP concentrations in the south. Although the INP concentrations differed by up to three orders of magnitude among these five sampling sites, all 47 snowmelt samples were within the ice nucleation spectra derived from worldwide precipitation samples. Samples collected from ZF presented the lowest INP concentrations, which were comparable with those in the Arctic regions. There was a significant correlation between the INP concentrations and the concentrations of representative chemical components of mineral dust particles (R > 0.75, P value < 0.01). Back trajectory analysis coupled with land cover data also suggested a strong dust source dependence of INPs: the higher the proportion of trajectory from barren and grass sources, the higher the INP concentrations.
These results reveal the abundance, distributions, and sources of INPs over the TP, and the INP concentration is controlled by seasonal East Asian dust. Further, the average annual cloud fractions and the cloud top temperatures of the five sampling regions are 42 ~ 65% and -27.0 ~ -17.2℃, respectively, meaning ample opportunities for aerosol-cloud interactions and suitable freezing temperature conditions for mineral INPs. Our work provides a comprehensive and extensive study of INPs over the TP, which could impact ice formation in clouds and may be a key link in understanding the radiation budget in this region.
How to cite: Wu, Z., Chen, J., Xu, J., Zhai, L., and Hu, M.: Mineral dust dominates the spatial distribution and impacts the climate effects of ice-nucleating particles over the Tibetan Plateau, China, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5415, https://doi.org/10.5194/egusphere-egu23-5415, 2023.
Posters virtual: Wed, 26 Apr, 08:30–10:15 | vHall AS
Clouds are large contributors to uncertainty in climate projections, with aerosol-cloud interactions playing a key role. To better reproduce heterogeneous ice clouds and, ultimately, the Earth’s changing energy budget in EC-Earth3 (one of the CMIP6 Earth System Models), its heterogeneous ice nucleation scheme has been updated. Specifically, the temperature-based parameterization has been substituted by a combination of aerosol-and-temperature-sensitive ice nucleating parameterizations. In particular, the model now considers a dust-and-soot-sensitive deposition nucleation scheme for cirrus clouds and aerosol-sensitive immersion freezing schemes for mixed-phase clouds. The latter is sensitive to the mineralogical composition of dust, specifically to the content of K-feldspar and quartz, and to marine organic aerosols, which are explicitly traced in EC-Earth3. Moreover, a secondary ice production parameterization based on a random forest regressor enhances the ice formed by the primary processes.
We evaluate the model against an extended observational dataset of INP concentrations and analyze the effect of modelled aerosols upon heterogeneous ice nucleation in mixed-phase clouds and cirrus clouds produced with the new parameterizations. We also investigate the sensitivity of the simulated liquid and ice water content and the atmospheric radiative fluxes to the two different soil mineralogy atlases. Additionally, we use this updated model version to study in more detail a severe dust intrusion event that produced dust-infused clouds that affected Europe in March 2022.
The results with the new ice nucleation parameterizations show a clear association of the simulated ice crystal number concentrations with the aerosol sources and transported regions. We also show that replacing the temperature-dependent ice nucleation parameterization with an aerosol-sensitive parameterization in EC-Earth3 significantly impacts surface temperature at high latitudes.
How to cite: Costa-Surós, M., Gonçalves, M., Chatziparaschos, M., Georgakaki, P., Ilić, L., Montane, G., Myriokefalitakis, S., van Noije, T., Le Sager, P., Kanakidou, M., Nenes, A., and Pérez García-Pando, C.: New Aerosol-sensitive Heterogeneous Ice Nucleation Parameterization in the EC-Earth3 Earth System Model: evaluation and climate response, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-13040, https://doi.org/10.5194/egusphere-egu23-13040, 2023.
