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Ice clouds play a key role in the atmospheric radiation budget, both by reflection of shortwave radiation and absorption-emission of longwave radiation. Through these radiative interactions, ice clouds can set atmospheric temperature gradients and thereby influence atmospheric circulation regimes. The radiative signature of ice clouds strongly depends on their macro- and microphysical characteristics, as well as their optical properties. While the new generation of storm-resolving models improves the representation of the vertical velocities that drive cloud formation, subgrid-scale differences, for example in ice optics and microphysics, generate large variability in the modeled atmospheric cloud-radiative heating (CRH) rates (Sullivan and Voigt, 2021). We propose both an idealized single-column and more realistic two-dimensional transect approach for investigating CRH, using the new ecRad radiative transfer module (Hogan and Bozzo, 2018). First, in a series of single-column calculations, we evaluate the impact of realistic perturbations in macro- and microphysical properties, such as cloud-top temperature and ice crystal effective radius, on CRH. For this approach, a heating sensitivity matrix visualization is presented as the response for the different levels of macro-micro properties perturbations. Secondly, we study the impact of using three different ice optical schemes (Fu, 1996; Fu et al., 1998; Yi et al., 2013; Baran et al., 2016) on CRH over three latitudinal transects located in the Eastern Pacific, Western Pacific, and passing over the Asian Monsoon Area. For each of these transects, ecRad is driven by realistic atmospheric conditions provided by ERA5.

Cirrus clouds play an important role in the Earth's energy budget by reflecting solar radiation and trapping long wave radiation from the surface. While globally, they are believed to have a net warming effect on the atmosphere, the regional differences in the cirrus cloud radiative effect (CRE) can be significant. In the polar regions, where there is restricted solar radiation or high surface albedo, cirrus clouds have a strong warming effect on the atmosphere. However, the uncertainties in calculating the cirrus cloud CRE remains significant, partly due to the incomplete understanding of ice crystal optical properties. To address this issue, in-situ observations of Arctic cirrus ice crystal microphysical and optical properties were made using the Particle Habit Imaging and Polar Scattering (PHIPS) probe during the CIRRUS-HL airborne measurement campaign in the summer of 2021. The observations are used to generate a new parameterisation of ice crystal single scattering properties, which is tested in radiative transfer simulations to determine the CRE of Arctic cirrus during the polar day. The study highlights the key microphysical properties that define the magnitude of the ice cloud asymmetry parameter and provides a more accurate estimate of the CRE of cirrus clouds, particularly in the polar regions. The findings have significant implications for climate modelling and weather forecasting, and they demonstrate the importance of using direct in-situ observations to improve our understanding of the optical properties of cirrus clouds., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The interaction of solar radiation with ice particles in clouds plays a crucial role in redistributing solar light. Understanding this process is essential for accurate calculations of the shortwave radiative transfer in climate models and for retrieving cloud properties from satellite observations. However, current knowledge of the light scattering behavior of atmospheric ice particles is limited using simplified ice particle morphologies in optical models.To address this limitation, the Particle Habit Imaging and Polar Scattering (PHIPS) airborne probe was developed to obtain in-situ measurements of single atmospheric ice crystals. The PHIPS probe is a combination of a stereo microscopic bright field imager and a polar nephelometer that works on single particles. By using PHIPS, a unique and comprehensive dataset of microphysical properties and correlated angular light scattering functions of real atmospheric ice particles has been acquired from several aircraft campaigns.The acquired dataset is of high value for scientists developing and applying single particle light scattering models. By simulating the light scattering behavior of the observed crystals with the optical engineering software FRED, the study shows that even solid hexagonal crystals require surface roughness assumptions to accurately explain their light scattering function. The study tests two surface roughness models: the tilted-facet angle distribution method and the "smooth surface roughness" approach, which assumes scalar diffraction on wavelength-scale roughness features. The performance of these two models for the example crystals is discussed. Overall, this study demonstrates the importance of in-situ measurements for improving our understanding of the light scattering behavior of atmospheric ice particles., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Tiivistelmä. Big Room on etenkin isoissa rakennusalan allianssihankkeissa käytettävä konsepti, jonka tarkoituksena on tehostaa tiedonkulkua ja vähentää päätöksenteon hidasteita keräämällä projektin eri sidosryhmät samaan fyysiseen tilaan. Teknologisen kehityksen ja viime vuosien pandemian vauhdittamana Big Roomin järjestäminen fyysisen tilan sijaan virtuaalisena on kuitenkin lisääntynyt. Tämä on puolestaan lisännyt tarvetta löytää ratkaisuja Big Roomin tärkeiden elementtien, kuten kommunikoinnin, tiedon jakamisen ja erilaisten projektinhallinnan työkalujen korvaamiseksi virtuaalisessa muodossa niin, että sen hyödyt säilyvät. Tämän kandidaatintyön tavoitteena on tutkia virtuaalisen Big Roomin käsitettä sekä löytää vaihtoehtoja Big Roomin tärkeimpien elementtien virtualisoimisessa käytettäville ohjelmistoille ja työkaluille. Tutkimusmenetelmänä tässä työssä käytetään kirjallisuuskatsausta perustuen aiheesta aiemmin tehtyyn tutkimukseen. Tutkimuksessa löydettiin useita vaihtoehtoja työkaluiksi ja ohjelmistoiksi fyysisen Big Roomin tärkeimpien elementtien virtualisoimiseen. Työssä esitetään löydettyjen ohjelmistojen ja työkalujen valintakriteerejä virtuaaliseen Big Roomiin, kuten projektin työntekijöiden aikaisempaa kokemusta sovelluksista sekä ominaisuuksien laajuutta. Lisäksi työssä ehdotetaan ohjelmistoista ja työkaluista koostettu esimerkkipaketti, joka virtualisoi Big Roomin tärkeimmät toiminnallisuudet sekä pienessä, että suuressa projektissa.The software and tools of virtual Big Room. Abstract. Big Room is a concept that is mostly used in big construction project alliances. The purpose of Big Room is to make flow of information more effective and lessen the time used in decision-making by gathering the stakeholders in the same room. The last two years’ global pandemic combined with the technological evolution has sped up the process to transfer from physical Big Rooms to virtual ones. This transfer has increased the need of solutions to replace the important elements of physical Big Room, like communication, knowledge sharing, and various project management tools, so the virtual Big Room will have the same positive impact as physical Big Room. The goal of this bachelor’s thesis will be to explain the concept of Big Room and to find possible software and tools to virtualize the most important elements of Big Room. The method used in this thesis is literature review based on the earlier study of Big Room. This thesis depicts different criteria, like the project’s stakeholders’ earlier experience of the apps or the scope of the provided features in choosing of the software and tools to virtualize the Big Room. This thesis also provides an example of a package for small and big projects that consists of the software and tools to virtualize the most important elements of Big Room.

Background: Cladribine tablets for adult patients with highly active relapsing multiple sclerosis (MS) have been available in Finland since 2018. Real-world data from different genetic and geographical backgrounds are needed to complement data from clinical trials. Methods: We investigated the use of cladribine tablets in Finland in a non-interventional cohort study, based on real-world data from the nationwide Finnish MS registry. All eligible patients who had initiated treatment with cladribine tablets in 2018–2020 were included. Descriptive analyses for outcomes were conducted using summary statistics. Time-dependent endpoints were analyzed using cumulated events analysis based on 1-Kaplan–Meier estimates and curves. Subgroups were analyzed separately according to the number of previous disease-modifying therapies (DMTs) and the most common last preceding therapies. Results: Data of 179 patients were analyzed. Median follow-up time was 19.0 months (interquartile range [IQR] 12.0–26.2). Of the 134 patients who were followed for at least 12 months, 112 patients (83.6%) remained relapse-free during follow-up. Mean annualized relapse rate (ARR) was 1.0 (standard deviation [SD] 0.89) at baseline, and 0.1 (SD 0.30) at follow-up. Patients with two or more previous DMTs had shorter time to first relapse (median 2.5 months, IQR 0.6–9.3) when compared to patients with 0–1 previous DMTs (median 11.4 months, IQR 8.7–13.1) (p=0.013). After excluding patients switching from fingolimod (n=33), a statistically significant difference in time to first relapse was no longer observed between the two groups (p=0.252). Adverse events (AEs) were reported in 30 patients (16.8%). The most frequent AE was headache (n=14, 7.8%). One patient (0.6%) died of cardiac arrest. Discontinuation of cladribine tablets was reported in nine patients (5.0%). Conclusions: The mean ARR observed in this cohort was similar to what has been reported in clinical trials. Approximately half of the patients had used two or more previous DMTs before cladribine tablets. These patients had a shorter time to first relapse when compared to patients with 0–1 previous DMTs, mostly driven by early relapses in patients switching from fingolimod.

Tiivistelmä. Tutkimuksen tarkoituksena on kuvailla miten moniammatillista kuntoutumista edistävää työotetta tukevat ja estävät tekijät sekä työotteeseen vaikuttava lähiesimiehen toiminta näyttäytyvät yliopistosairaalan kirurgisilla ja sisätautisilla vuodeosastoilla. Tutkimuksen tavoitteena on tuottaa ajankohtaista tietoa moniammatillisen kuntoutumista edistävän työotteen nykytilasta yliopistosairaalan vuodeosastoilla. Tavoitteena on, että tuotettua tietoa voidaan jatkossa hyödyntää osastojen toiminnan kehittämisessä ja työyksikkökohtaisten kehittämissuunnitelmien ja toimintamallien laatimisessa sekä lähiesimiesten johtamisosaamisen kehittämisessä moniammatillista kuntoutumista edistävää työotetta tukevaksi. Tutkimuksen aineisto koostuu kymmenestä teemahaastattelusta. Haastatteluihin osallistui vuodeosastojen sekä niillä työskentelevän terapiahenkilöstön lähiesimiehiä sekä sairaanhoitajia, fysioterapeutteja ja toimintaterapeutteja. Aineisto analysoitiin induktiivisella sisällön analyysillä. Tutkimuksen perusteella voidaan todeta, että hoitohenkilöstö ja heidän esimiehensä ovat yhtä mieltä siitä, mitkä työotteeseen vaikuttavat tekijät tällä hetkellä tukevat ja mitkä estävät moniammatillisen kuntoutumista edistävän työotteen toteutumista yliopistosairaalan vuodeosastoilla. Lähiesimiehen toiminta sekä työyhteisön ilmapiiri koetaan edistävinä tekijöinä, joiden varaan on tulevaisuudessa hyvä lähteä kehittämään työotetta tukevia yhteisiä toimintamalleja. Suurimmat kehittämistarpeet koskevat moniammatillisen tiimin eri ammattilaisten roolien tunnistamista ja esille tuomista sekä merkityksellisen tiedon siirtymisen varmistamista kommunikointia ja vuorovaikutusta kehittämällä. Jatkossa olisi tarpeen tehdä tutkimusta siitä, että miten moniammatillista kuntoutumista edistävää työotetta on pystytty jalkauttamaan työyksiköihin sitä edistävällä johtamisella ja millaisia hyötyjä tästä on seurannut organisaatioiden moniammatillisen johtamisen sekä asiakkaiden näkökulmasta.Multiprofessional rehabilitation approach in university hospital wards : promoting and hindering factors. Abstract. The purpose of this study was to describe how factors promoting and hindering a multiprofessional rehabilitation approach and the first line manager actions impacting the approach manifested in the surgical and medical wards of a university hospital. The aim of the study is to produce up-to-date information about the current status of multiprofessional rehabilitation approach in the wards of a university hospital. The objective is that the information produced could in future be utilised to develop ward practices and to draw up work unit-specific development plans and approaches, as well as to develop first line managers’ management skills which promote a multiprofessional approach. The study material consisted of ten thematic interviews. The interviewees included first line managers of the therapy and staff working in wards as well as nurses, physiotherapists and occupational therapists. The data were analysed using inductive content analysis. The results of the study show that nursing staff and managers agree on the factors that currently promote or hinder the implementation of a multiprofessional rehabilitation approach in the university hospital wards. The actions of first line manager and the atmosphere in the work unit were perceived as promoting factors which should serve as a basis when developing a common framework promoting a rehabilitation approach. The greatest development needs are related to identifying the roles of the professionals involved in multiprofessional teamwork and ensuring the transfer of significant information through increased communication and interaction. In future, research should focus on how successfully practices that promote a multiprofessional rehabilitation approach have been implemented in work units through supportive management. In addition, the benefits this has resulted in from the viewpoint of organisations’ multiprofessional management and clients would also warrant further study.

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This research thesis aimed to deepen understanding about the nature of technology and its possible correspondence to the constructivist notion of learning. Since technology education is a relatively new subject area in general education and still in an emerging phase in various countries, it provided some interesting opportunities to take into account the latest developments in educational psychology in relation to the development of teaching technology. Moreover, this thesis aimed at finding ways for technology education to provide possibilities to learning environments where the nature of technology could be integrated effectively into the current notion of children as active agents in their learning processes. The thesis was based on two Case Studies. Both of the Case Studies were carried out on the primary school level. The overall purpose of Case Study I was to consider automation technology and its teaching as a subject-matter area in developing technology education in Finland. In Case Study II the purpose was to explore the influences of socio-cultural interaction on children’s thinking and actions in prescribed and open problem-solving situations while they were technologically creating a particular product which used sound for a chosen purpose. Case Study II also involved English schoolchildren. Teaching methods throughout the thesis were based on the assumption that constructivist-driven, open, and creative problem solving, as well as children-centered approaches, are especially suitable for technology education. This assumption arises from the notions that innovation and problem solving are important in technological processes and that technology has usually emerged as a response to human needs and wants. Consequently, design briefs were developed to provide open, children-centered problem solving based on the acute needs found in the children’s own living environment. In both of the Case Studies multiple data collection procedures were applied. In Case Study I data were collected by means of group observations documented in videotaped recordings, written field notes and project files saved by the students. Moreover, In Case Study II data were collected in terms of photographs of the pupils’ final outcomes, including pupils’ design folders and product evaluations, the teacher’s teaching notes, teacher’s lesson evaluation notes, the researcher’s field notes based on observations and a questionnaire. The methodological perspective in both of the Case Studies was qualitative in nature and grounded on inductive and interpretative data-based analysis. The analysis employed an open search for categories, concepts and patterns emerging from the data. The inductive interpretative analysis process enabled the results to be framed as empirical assertions. In addition to the assertions the results of Case Study I detailed content classifications of the substance in the focus were included as well. The assertions and the classifications were supported by evidentiary examples taken from the data. The supporting examples were interpreted from the viewpoint of the research problems. The results of the thesis suggested that in technology education it is important for children to be able to work and learn in a way that fosters open problem solving with innovation and divergent thinking. In technology education the design briefs and task allocations should be open enough to allow the children to explore their own living environment in order to find problems that need to be solved. Actually, in technology education, according to the nature of technology, there should not be right answers to the posed questions, but rather appropriate solutions to emerging problems. Moreover, teaching methods adjusted according to the nature of technology ensure naturally that the children are treated as active, intentional and goal-directed humans whose activities are driven by human volition. Tiivistelmä Tämä tutkimus pyrki syventämään ymmärtämystä teknologian luonteesta ja sen mahdollisesta vastaavuudesta konstruktivistiseen oppimiskäsitykseen. Teknologiakasvatus on suhteellisen uusi ala yleissivistävässä koulutuksessa ja se on edelleen sukeutuvassa vaiheessa useissa maissa. Tällainen tilanne antoi mielenkiintoisia mahdollisuuksia ottaa huomioon viimeisimpiä oppimispsykologisia virtauksia suhteessa teknologian opetuksen kehittämiseen. Lisäksi tutkimus pyrki etsimään teknologiakasvatukselle mahdollisuuksia sellaisten oppimisympäristöjen luomiseen, joissa teknologian luonne voitaisiin tehokkaasti integroida nykyiseen käsitykseen lapsista oppimisprosessiensa aktiivisina tekijöinä. Tämä tutkimus perustui kahteen tapaustutkimukseen (Case Studies). Kummatkin tapaukset toteutettiin peruskoulun ala-asteella. Ensimmäiseen tapauksen (Case Study I) yleisenä tarkoituksena oli tarkastella automaatioteknologiaa ja sen opetusta sisältöalueena osana teknologiakasvatuksen kehittämispyrkimyksiä. Toisessa tapauksessa (Case Study II) tarkoituksena oli tutkia sosio-kulttuurillisen vuorovaikutuksen vaikutusta lasten ajatteluun ja toimintaan avoimissa ja suljetuissa ongelmanratkaisutilanteissa. Tässä tapauksessa lapset tekivät valittavaan tarkoitukseen ääntä tuottavia laitteita ja siihen osallistui myös englantilaisia koululaisia. Tutkimuksessa käytetyt opetusmetodit perustuivat oletukseen, että konstruktivismiin pohjautuvat, avointa ja luovaa ongelmanratkaisua sekä oppilaskeskeisyyttä korostavat lähestymistavat ovat erityisen soveliaita teknologiakasvatuksessa käytettäviksi. Tämä oletus nousee käsityksestä, jossa innovatiivisuus ja ongelmanratkaisu ovat tärkeitä teknologisille prosesseille ja että teknologia esiintyy vastauksena ihmisen tarpeisiin. Oppilaille annetut tehtävät määriteltiinkin sellaisiksi, että ne mahdollistivat avoimen, oppilaskeskeisen ongelmanratkaisun perustuen lasten omasta elinpiiristään esiin nousevien tarpeiden tyydyttämiseen. Molemmissa tapauksissa tutkimusaineistoa kerättiin usealla eri tavalla. Ensimmäisessä tapauksessa tutkimusaineistoa kerättiin oppilasryhmiä havainnoimalla mm. videonauhoituksin ja kenttäpäiväkirjaa kirjoittamalla sekä tallentamalla levykkeelle ryhmien projektissa luomat tiedostot. Tämän lisäksi toisessa tapauksessa tutkimusaineistoa kerättiin valokuvaamalla oppilaiden suunnittelukansiot tuotteen itse arviointeineen ja heidän valmistamansa työt. Tässä tapauksessa tallennettiin myös opettajan opetuksestaan tekemiä havaintoja ja arviointeja, tutkimuspäiväkirjaan tehdyt observointimuistiinpanot sekä oppilaille järjestetyn kyselyn tulokset. Molemmat tapaukset olivat metodologisesti laadullisia tutkimuksia ja perustuivat induktiiviseen ja tulkitsevaan aineistopohjaiseen analyysiin. Analyysissä kiinnitettiin huomiota nimenomaan tutkimusaineistosta esiin nouseviin käsitteisiin, lainalaisuuksiin ja säännönmukaisuuksiin. Tutkimuksen metodologinen valinta mahdollisti tulosten esittämisen empiirisinä väittäminä, joita tuettiin tutkimusaineistosta otetuilla esimerkeillä. Empiiristen väittämien lisäksi ensimmäisen tapauksen tulokset sisältävät tutkimusaineistosta esiin nousseita luokituksia analyysin kohteena olevista painotuksista. Sekä empiirisiä väittämiä, että luokituksia tuettiin tutkimusaineistosta otetuilla esimerkeillä. Esimerkit myös tulkittiin tutkimusongelmien näkökulmasta katsottuna. Tutkimuksen tuloksista voidaan päätellä, että teknologiakasvatuksessa on tärkeää antaa lapsille mahdollisuuksia työskennellä ja oppia tavalla, joka kehittää innovatiivista avointa ongelmanratkaisua ja divergenttiä ajattelua. Tässä mielessä annetut tehtävät tulisi olla niin avoimia, että lapsien olisi mahdollista löytää omasta elinpiiristään ratkaisua vaativia ongelmia. Itse asiassa teknologiakasvatuksessa, teknologian perusolemuksen mukaisesti, ei tulisi ollakaan vastauksia esitettyihin kysymyksiin, vaan tarkoituksemukaisia ratkaisuja esiintyviin ongelmiin. Lisäksi teknologian perusluonteen mukaiset opetusmenetelmät huomioivat lapsen sisäisesti toimintaan halukkaaksi motivoituneena ja aktiivisena sekä tarkoitus-ja päämäärähakuisena ihmisenä.

The present study was designed to test earlier findings of increased risk of lung cancer among iron foundry workers and to define the cause of the risk. The subjects were 3,425 workers with at least one year's employment in an iron foundry sometime between 1918 and December 31, 1972. The number (51) of cases of lung cancer which occurred prior to December 31, 1976 was statistically significantly higher than that expected, i.e., 35.3 based on proportional mortality. Molders and casters were determined to have the highest excess risk in a case-control study among the cohort. The worker groups with high exposure to polycyclic aromatic hydrocarbons (PAH) experienced a lung cancer risk higher than that of other groups, but the difference was not statistically significant.

Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the CLOUD experiment at CERN, we deployed a new in-situ optical method to detect the viscosity of α-pinene SOA particles and measured their transition from the amorphous viscous to liquid state. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical liquid particles during deliquescence. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to spherical shape was observed as the RH was increased to between 35 % at −10 °C and 80 % at −38 °C, confirming previous calculations of the viscosity transition conditions. Consequently, α-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere.

This study reports on the origin of ice crystal complexity and its influence on the angular light scattering properties of cirrus clouds. Cloud simulation experiments were conducted at the AIDA (Aerosol Interactions and Dynamics in the Atmosphere) cloud chamber of the Karlsruhe Institute of Technology (KIT). A new experimental procedure was applied to grow and sublimate ice particles at defined super- and subsaturated ice conditions and for temperatures in the −40 to −60 °C range. The experiments were performed for ice clouds generated via homogeneous and heterogeneous initial nucleation. Ice crystal complexity was deduced from measurements of spatially resolved single particle light scattering patterns by the latest version of the Small Ice Detector (SID-3). It was found that a high ice crystal complexity is dominating the microphysics of the simulated clouds and the degree of this complexity is dependent on the available water vapour during the crystal growth. Indications were found that the crystal complexity is influenced by unfrozen H2SO4/H2O residuals in the case of homogeneous initial ice nucleation. Angular light scattering functions of the simulated ice clouds were measured by the two currently available airborne polar nephelometers; the Polar Nephelometer (PN) probe of LaMP and the Particle Habit Imaging and Polar Scattering (PHIPS-HALO) probe of KIT. The measured scattering functions are featureless and flat in the side- and backward scattering directions resulting in low asymmetry parameters g around 0.78. It was found that these functions have a rather low sensitivity to the crystal complexity for ice clouds that were grown under typical atmospheric conditions. These results have implications for the microphysical properties of cirrus clouds and for the radiative transfer through these clouds.

Mixed phase clouds (MPCs) represent a great source of uncertainty for both climate predictions and weather forecasts. In particular, there is still a lack of understanding on how ice forms in these clouds. In this work we present a technique to analyze in situ measurements of MPCs performed with the latest instruments from the Small Ice Detector family. These instruments record high-resolution scattering patterns of individual small cloud particles. For the analysis of the scattering patterns we developed an algorithm that can discriminate the phase of the cloud particles. In the case of a droplet, a Mie solution is fitted to the recorded pattern and the size of the corresponding particle is obtained, which allows for a size calibration of the instrument. In the case of an ice particle, its shape is deduced from the scattering pattern. We apply our data analysis method to measurements from three distinct MPC types. The results from laboratory measurements demonstrate that our technique can discriminate between droplets and ice particles in the same optical size range. This ability was verified by measurements at a mountain top station where we found an alternation of liquid- and ice-dominated cloud regions. The analysis of results from aircraft-based measurements illustrates the ice detection threshold of the technique.

Mixed phase clouds (MPCs) represent a great source of uncertainty for both climate predictions and weather forecasts. In particular, there is still a lack of understanding on how ice forms in these clouds. In this work we present a technique to analyze in situ measurements of MPCs performed with the latest instruments from the Small Ice Detector family. These instruments record high resolution scattering patterns of individual small cloud particles. For the analysis of the scattering patterns we developed an algorithm that can discriminate the phase of the cloud particles. In the case of a droplet, a Mie solution is fitted to the recorded pattern and the size of the corresponding particle is obtained, which allows for a size calibration of the instrument. In the case of an ice particle, its shape and roughness are deduced from the scattering pattern. We apply our data analysis method to measurements from three distinct MPC types. The results from laboratory measurements demonstrate that our technique can discriminate between droplets and ice particles in the same optical size range. This ability was verified by measurements at a mountain top station where we found an alternation of liquid and ice dominated cloud regions. The analysis of results from aircraft based measurements illustrates the ice detection threshold of the technique.

There are strong indications that particles containing secondary organic aerosol (SOA) exhibit amorphous solid or semi-solid phase states in the atmosphere. This may facilitate heterogeneous ice nucleation and thus influence cloud properties. However, experimental ice nucleation studies of biogenic SOA are scarce. Here, we investigated the ice nucleation ability of viscous SOA particles. The SOA particles were produced from the ozone initiated oxidation of α-pinene in an aerosol chamber at temperatures in the range from -38 to -10° C at 5–15% relative humidity with respect to water to ensure their formation in a highly viscous phase state, i.e. semi-solid or glassy. The ice nucleation ability of SOA particles with different sizes was investigated with a new continuous flow diffusion chamber. For the first time, we observed heterogeneous ice nucleation of viscous α-pinene SOA for ice saturation ratios between 1.3 and 1.4 significantly below the homogeneous freezing limit. The maximum frozen fractions found at temperatures between -39.0 and -37.2° C ranged from 6 to 20% and did not depend on the particle surface area. Global modelling of monoterpene SOA particles suggests that viscous biogenic SOA particles are indeed present in regions where cirrus cloud formation takes place. Hence, they could make up an important contribution to the global ice nucleating particle budget.