Ilmatieteen laitos

Recent Submissions

  • Sofieva, Viktoria F.; Hänninen, Risto; Sofiev, Mikhail; Szeląg, Monika; Lee, Hei Shing; Tamminen, Johanna; Retscher, Christian (Copernicus Publications, 2022)
    Atmospheric measurement techniques
    Satellite measurements in nadir and limb viewing geometry provide a complementary view of the atmosphere. An effective combination of the limb and nadir measurements can give new information about atmospheric composition. In this work, we present tropospheric ozone column datasets that have been created using a combination of total ozone columns from OMI (Ozone Monitoring Instrument) and TROPOMI (TROPOspheric Monitoring Instrument) with stratospheric ozone column datasets from several available limb-viewing instruments: MLS (Microwave Limb Sounder), OSIRIS (Optical Spectrograph and InfraRed Imaging System), MIPAS (Michelson Interferometer for Passive Atmospheric Sounding), SCIAMACHY (SCanning Imaging Spectrometer for Atmospheric CHartographY), OMPS-LP (Ozone Mapping and Profiles Suite – Limb Profiler), and GOMOS (Global Ozone Monitoring by Occultation of Stars). We have developed further the methodological aspects of the assessment of tropospheric ozone using the residual method supported by simulations with the chemistry transport model SILAM (System for Integrated modeLling of Atmospheric coMposition). It has been shown that the accurate assessment of ozone in the upper troposphere and the lower stratosphere (UTLS) is of high importance for detecting the ground-level ozone patterns. The stratospheric ozone column is derived from a combination of ozone profiles from several satellite instruments in limb-viewing geometry. We developed a method for the data homogenization, which includes the removal of biases and a posteriori estimation of random uncertainties, thus making the data from different instruments compatible with each other. The high-horizontal- and vertical-resolution dataset of ozone profiles is created via interpolation of the limb profiles from each day to a 1◦ × 1◦ horizonal grid. A new kriging-type interpolation method, which takes into account data uncertainties and the information about natural ozone variations from the SILAM-adjusted ozone field, has been developed. To mitigate the limited accuracy and coverage of the limb profile data in the UTLS, a smooth transition to the model data is applied below the tropopause. This allows for the estimation of the stratospheric ozone column with full coverage of the UTLS. The derived ozone profiles are in very good agreement with collocated ozonesonde measurements. The residual method was successfully applied to OMI and TROPOMI clear-sky total ozone data in combination with the stratospheric ozone column from the developed highresolution limb profile dataset. The resulting tropospheric ozone column is in very good agreement with other satellite data. The global distributions of tropospheric ozone exhibit enhancements associated with the regions of high tropospheric ozone production. The main datasets created are (i) a monthly 1◦ × 1◦ global tropospheric ozone column dataset (from ground to 3 km below the tropopause) using OMI and limb instruments, (ii) a monthly 1◦ × 1◦ global tropospheric ozone column dataset using TROPOMI and limb instruments, and (iii) a daily 1◦ × 1◦ interpolated stratospheric ozone column from limb instruments. Other datasets, which are created as an intermediate step of creating the tropospheric ozone column data, are (i) a daily 1◦ × 1◦ clear-sky and total ozone column fromOMI and TROPOMI, (ii) a daily 1◦ × 1◦ homogenized and interpolated dataset of ozone profiles from limb instruments, and (iii) a daily 1◦×1◦ dataset of ozone profiles from SILAM simulations with adjustment to satellite data. These datasets can be used in various studies related to variability and trends in ozone distributions in both the troposphere and the stratosphere. The datasets are processed from the beginning of OMI and TROPOMI measurements until December 2020 and are planned to be regularly extended in the future.
  • Zhang, Weihua; Paatero, Jussi; Leppänen, Ari-Pekka; Møller, Bredo; Jensen, Louise Kiel; Gudnason, Kjartan; Sofiev, Mikhail; Anderson, Pål; Sickel, Morten; Burakowska, Agnieszka; Kubicki, Marek; Anderson, Amanda (Elsevier., 2022)
    Journal of environmental radioactivity
    This paper provides a brief introduction to the Arctic atmospheric radioactivity monitoring network. A decade of monitoring results have shown the 137Cs background levels in Arctic air range from 0.05 to 1.50 μBq/m3. The monitoring stations have sufficient sensitivity to detect 137Cs brought to the atmosphere due to resuspension in local soil and reemissions from biomass burning in a daily temporal resolution. These observations can be used as tracers for atmospheric processes. The 133Xe measurements obtained at Yellowknife, Resolute and Spitsbergen could support other research into how air pollution problems arise across intercontinental distances. It will help develop and improve models capable of predicting the long-distance transport and deposition of trace gases in the Arctic. Rainwater monitoring data collected in Finnish Lapland since the 1960’s indicate that 3H radioactivity concentrations reached natural background levels in early 2000s, typically around 1–2 Bq/L monthly, with an annual seasonal variation cycle consistent with the observed of other cosmogenic radionuclides.
  • Varentsov, A I; Stepanenko, V M; Mortikov, E V; Debolskiy, A V; Kouznetsov, R D; Sofiev, M (IOP Publishing, 2022)
    IOP conference series Earth and environmental science
    The paper presents the results of one-way coupling of a large eddy simulation model and an atmospheric composition and diffusion complex SILAM. This study investigates a possibility of large eddy simulation time data coarsening (filtering) for use in SILAM for microscale calculations. Experiments with scalar tracers with a limited lifetime are carried out under conditions of convective boundary layer. A comparison between the calculations with filtered and nonfiltered data demonstrate that time data coarsening is possible without a significant loss in accuracy for tracers whose lifetime is much longer than the coarsening scale and the timestep of the filtered data
  • Tummon, Fiona; Bruffaerts, Nicolas; Celenk, Sevcan; Choël, Marie; Clot, Bernard; Crouzy, Benoît; Galán, Carmen; Gilge, Stefan; Hajkova, Lenka; Mokin, Vitalii; O’Connor, David; Rodinkova, Victoria; Sauliene, Ingrida; Sikoparija, Branko; Sofiev, Mikhail; Sozinova, Olga; Tesendic, Danijela; Vasilatou, Konstantina (Pitagora Editrice., 2022)
    Standards for manual pollen and fungal spore monitoring have been established based on several decades of experience, tests, and research. New technological and methodological advancements have led to the development of a range of different automatic instruments for which no standard yet exist. This paper aims to provide an overview of aspects that need to be considered for automatic pollen and fungal spore monitoring, including a set of guidelines and recommendations. It covers issues relevant to developing an automatic monitoring network, from the instrument design and calibration through algorithm development to site selection criteria. Despite no official standard yet existing, it is essential that all aspects of the measurement chain are carried out in a manner that is as standardised as possible to ensure high-quality data and information can be provided to end-users.
  • Sofiev, Mikhail; Sofieva, Svetlana; Palamarchuk, Julia; Šaulienė, Ingrida; Kadantsev, Evgeny; Atanasova, Nina; Fatahi, Yalda; Kouznetsov, Rostislav; Kuula, Joel; Noreikaite, Auste; Peltonen, Martina; Pihlajamäki, Timo; Saarto, Annika; Svirskaite, Julija; Toiviainen, Linnea; Tyuryakov, Svyatoslav; Šukienė, Laura; Asmi, Eija; Bamford, Dennis; Hyvärinen, Antti-Pekka; Karppinen, Ari (Elsevier., 2022)
    Environmental research
    A coordinated observational and modelling campaign targeting biogenic aerosols in the air was performed during spring 2021 at two locations in Northern Europe: Helsinki (Finland) and Siauliai (Lithuania), approximately 500 km from each other in north-south direction. The campaign started on March 1, 2021 in Siauliai (12 March in Helsinki) and continued till mid-May in Siauliai (end of May in Helsinki), thus recording the transition of the atmospheric biogenic aerosols profile from winter to summer. The observations included a variety of samplers working on different principles. The core of the program was based on 2- and 2.4–hourly sampling in Helsinki and Siauliai, respectively, with sticky slides (Hirst 24-h trap in Helsinki, Rapid-E slides in Siauliai). The slides were subsequently processed extracting the DNA from the collected aerosols, which was further sequenced using the 3-rd generation sequencing technology. The core sampling was accompanied with daily and daytime sampling using standard filter collectors. The hourly aerosol concentrations at the Helsinki monitoring site were obtained with a Poleno flow cytometer, which could recognize some of the aerosol types. The sampling campaign was supported by numerical modelling. For every sample, SILAM model was applied to calculate its footprint and to predict anthropogenic and natural aerosol concentrations, at both observation sites. The first results confirmed the feasibility of the DNA collection by the applied techniques: all but one delivered sufficient amount of DNA for the following analysis, in over 40% of the cases sufficient for direct DNA sequencing without the PCR step. A substantial variability of the DNA yield has been noticed, generally not following the diurnal variations of the total-aerosol concentrations, which themselves showed variability not related to daytime. An expected upward trend of the biological material amount towards summer was observed but the day-today variability was large. The campaign DNA analysis produced the first high-resolution dataset of bioaerosol composition in the NorthEuropean spring. It also highlighted the deficiency of generic DNA databases in applications to atmospheric biota: about 40% of samples were not identified with standard bioinformatic methods.
  • Im, Ulas; Geels, Camilla; Hanninen, Risto; Kukkonen, Jaakko; Rao, Shilpa; Ruuhela, Reija; Sofiev, Mikhail; Schaller, Nathalie; Hodnebrog, Øivind; Sillmann, Jana; Schwingshackl, Clemens; Christensen, Jesper H.; Bojariu, Roxana; Aunan, Kristin (Frontiers Media S.A., 2022)
    Frontiers in environmental science
    Feedbacks between air pollutants and meteorology play a crucial role in the direction of the response of future climate and air pollution. These feedbacks are important to understand and quantify the potential impact of adaptation and mitigation policies setup for protecting the population against air pollution and heat stress. We review the interactions between climate and air pollution, with special focus on the projections of air pollution under different future climate scenarios and time horizons, based on a literature review of research articles and reports from the last decade. The assessment focuses on 1) the specific impacts of climate change on air pollution and natural particle and precursor emissions in Europe in the near future (2030), by mid-century (2050) and by end of the century (2100), 2) impacts on air pollution due to changes in emissions vs. changes in climate, 3) feedbacks from air pollution on climate, 4) impacts of climate change on wildland fires and air pollutant levels, and 5) the role of adaptation and mitigation policies on climate change and air pollution. Available literature to a large extent suggests that ozone concentrations will likely increase in the second half of the century by up to 9 ppb [−4 + 9.3], while in the first half of the century, changes are much smaller and are up to ±1.5 ppb. These changes are mainly attributed to increased temperatures and emissions of biogenic volatile organic compounds, but also depends on the models and scenarios used in these studies. On the other hand, the predicted changes in particle concentrations and chemical composition are uncertain and much smaller. Similar to ozone, larger changes in the particle concentrations are projected in the second half of the century. The main conclusion from this review is that the estimated changes in pollutant levels in the future vary significantly depending on the applied model systems, as well as the different emission or meteorological scenarios used in the different studies. Nevertheless, studies generally agree on the overall trend of the changes in pollutant levels due to climate change, in particular in the second half of the century.
  • van Daalen, Kim R; Romanello, Marina; Rocklöv, Joacim; Semenza, Jan C; Tonne, Cathryn; Markandya, Anil; Dasandi, Niheer; Jankin, Slava; Achebak, Hicham; Ballester, Joan; Bechara, Hannah; Callaghan, Max W; Chambers, Jonathan; Dasgupta, Shouro; Drummond, Paul; Farooq, Zia; Gasparyan, Olga; Gonzalez-Reviriego, Nube; Hamilton, Ian; Hänninen, Risto; Kazmierczak, Aleksandra; Kendrovski, Vladimir; Kennard, Harry; Kiesewetter, Gregor; Lloyd, Simon J; Lotto Batista, Martin; Martinez-Urtaza, Jaime; Milà, Carles; Minx, Jan C; Nieuwenhuijsen, Mark; Palamarchuk, Julia; Quijal-Zamorano, Marcos; Robinson, Elizabeth J Z; Scamman, Daniel; Schmoll, Oliver; Sewe, Maquins Odhiambo; Sjödin, Henrik; Sofiev, Mikhail; Solaraju-Murali, Balakrishnan; Springmann, Marco; Triñanes, Joaquin; Anto, Josep M; Nilsson, Maria; Lowe, Rachel (Elsevier Ltd., 2022)
    The Lancet. Public health
    In the past few decades, major public health advances have happened in Europe, with drastic decreases in premature mortality and a life expectancy increase of almost 9 years since 1980. European countries have some of the best health-care systems in the world. However, Europe is challenged with unprecedented and overlapping crises that are detrimental to human health and livelihoods and threaten adaptive capacity, including the COVID-19 pandemic, the Russian invasion of Ukraine, the fastest-growing migrant crisis since World War 2, population displacement, environmental degradation, and deepening inequalities. Compared with pre-industrial times, the mean average European surface air temperature increase has been almost 1°C higher than the average global temperature increase, and 2022 was the hottest European summer on record. As the world’s third largest economy and a major contributor to global cumulative greenhouse gas emissions, Europe is a key stakeholder in the world’s response to climate change and has a global responsibility and opportunity to lead the transition to becoming a low-carbon economy and a healthier, more resilient society. The Lancet Countdown in Europe is a collaboration of 44 leading researchers, established to monitor the links between health and climate change in Europe and to support a robust, evidence-informed response to protect human health. Mirroring the Global Lancet Countdown, this report monitors the health effects of climate change and the health co-benefits of climate action in Europe. Indicators will be updated on an annual basis and new indicators will be incorporated to provide a broad overview to help guide policies to create a more climate-resilient future.
  • Aakko-Saksa, Päivi T.; Lehtoranta, Kati; Kuittinen, Niina; Järvinen, Anssi; Jalkanen, Jukka-Pekka; Johnson, Kent; Jung, Heejung; Ntziachristos, Leonidas; Gagné, Stéphanie; Takahashi, Chiori; Karjalainen, Panu; Rönkkö, Topi; Timonen, Hilkka (Elsevier Science, 2023)
    Progress in energy and combustion science
    The impact of ship emission reductions can be maximised by considering climate, health and environmental effects simultaneously and using solutions fitting into existing marine engines and infrastructure. Several options available enable selecting optimum solutions for different ships, routes and regions. Carbon-neutral fuels, including low-carbon and carbon-negative fuels, from biogenic or non-biogenic origin (biomass, waste, renewable hydrogen) could resemble current marine fuels (diesel-type, methane and methanol). The carbon-neutrality of fuels depends on their Well-to-Wake (WtW) emissions of greenhouse gases (GHG) including carbon dioxide (CO2), methane (CH4), and nitrous oxide emissions (N2O). Additionally, non-gaseous black carbon (BC) emissions have high global warming potential (GWP). Exhaust emissions which are harmful to health or the environment need to be equally removed using emission control achieved by fuel, engine or exhaust aftertreatment technologies. Harmful emission species include nitrogen oxides (NOx), sulphur oxides (SOx), ammonia (NH3), formaldehyde, particle mass (PM) and number emissions (PN). Particles may carry polyaromatic hydrocarbons (PAHs) and heavy metals, which cause serious adverse health issues. Carbon-neutral fuels are typically sulphur-free enabling negligible SOx emissions and efficient exhaust aftertreatment technologies, such as particle filtration. The combinations of carbon-neutral drop-in fuels and efficient emission control technologies would enable (near-)zero-emission shipping and these could be adaptable in the short- to mid-term. Substantial savings in external costs on society caused by ship emissions give arguments for regulations, policies and investments needed to support this development
  • Prank, Marje; Tonttila, Juha; Ahola, Jaakko; Kokkola, Harri; Kühn, Thomas; Romakkaniemi, Sami; Raatikainen, Tomi (Copernicus Publ., 2022)
    Atmospheric chemistry and physics
    The goal of this study is to investigate the role of organic aerosols emitted with sea spray or formed from marine gas phase emissions of volatile organic compounds (VOCs) in influencing the stability of stratiform marine clouds. We aim to point out the processes and drivers that could be relevant for global climate and should thus be considered in large-scale models. We employ a large eddy simulator coupled with an aerosol–cloud microphysical model together with different parameterizations for emission of sea salt, primary organic aerosol, and VOCs from sea surface and formation of secondary organic aerosol (SOA), to simulate the conditions of the second Dynamics and Chemistry of Marine Stratocumulus observational campaign characterized by low-level stratocumulus clouds transitioning from closed cells to drizzling open cell structure. We find that the inclusion of sea spray emissions can both extend and shorten the transitioning timescale between closed and open cells based on the parameterization employed. Fine sea spray provides extra cloud condensation nuclei (CCN) and delays the onset of drizzle as the collision–coalescence process is slowed down due to smaller cloud droplet mean size. The coarse mode has an opposite effect due to giant CCN (GCCN) speeding up the drizzle formation through the enhanced collision–coalescence processes. The balance between two processes depends on the model parameterization employed. Compared to differences between different sea spray parameterizations, the sensitivity of the clouds to the variations in organic fraction of sea spray and hygro scopicity of the emitted particles is relatively limited. However, our results show that it is important to account for the size dependence of the sea spray organic fraction as attributing organic emissions to coarse mode noticeably reduces the GCCN effect. In addition, including the secondary organic aerosol formation from VOCs can potentially have a noticeable impact, but only when emitting the highest observed fluxes of monoterpenes. This impact is also highly sensitive on the size distribution of the background aerosol population. SOA production from isoprene is visible only if aqueous phase SOA production pathways are included, and even then, the effect is lower than from monoterpenes.
  • Hippi, Marjo (Ilmatieteen laitos - Finnish Meteorological Institute, 2022)
    Finnish Meteorological Institute Contributions 183
    Wintertime slip injuries are a very common problem in Finland as well as in other countries where winter conditions are frequent. According to surveys, on average every third person in Finland slips each winter and more than 50,000 persons are injured needing medical attention. Slipping causes human suffering as well as significant financial costs due to medical expenses and sick leaves. On some of the most slippery days, the number of slipping injuries can be so high that the hospital emergency departments are crowded with patients requiring surgery. The severity of slipping injuries typically increases with age. In addition, the number of slips and slip related injuries are more common among women than men. Finland has set a goal to increase the share of sustainable transport modes, such as walking and cycling, in the future. The aim is to reduce greenhouse gas emissions from transport and improve public health. Walking and cycling are to be the primary means of transport, especially for short distances in dense urban areas. In addition, the aim is to improve traffic safety and to develop walking and cycling infrastructure. This dissertation presents in which weather situations slips occur more than usual. In addition, the work presents a meteorological tool to help predicting weather conditions that cause pedestrian sidewalk slipperiness. Weather has a significant role in pedestrian’s wintertime slips and resulting injuries. In this dissertation, it has been investigated what are the weather situations that increase the risk of slipping and what is the spatio-temporal distribution of slips. Special attention has been given to situations with clearly more slips than usual, i.e. so called peak days of slipping injuries. The results show that snow and ice significantly increase the risk of slipping, and that most of the wintertime slips occur when the temperature is near zero degrees or slightly below it. This dissertation presents a numerical model predicting slipperiness from the pedestrian’s point of view. The model is developed at the Finnish Meteorological Institute. The thesis presents the physical principles of the model and how the slipperiness classification is implemented. The model is a tool for meteorologists to supports the decision making when issuing warnings about slippery sidewalk conditions. In addition, the model benefits winter road maintenance personnel and also public with better sidewalk condition and issued warnings. Climate change will have a major impact on future winters, especially in the northern latitudes. The winter season is shortened and near zero temperatures are becoming more frequent also during mid-winter, meaning more slippery conditions during that period. It is expected that the slip period will become shorter but at the same time more intense.
  • Meinander, Outi; Dagsson-Waldhauserova, Pavla; Amosov, Pavel; Aseyeva, Elena; Atkins, Cliff; Baklanov, Alexander; Baldo, Clarissa; Barr, Sarah L.; Barzycka, Barbara; Benning, Liane G.; Cvetkovic, Bojan; Enchilik, Polina; Frolov, Denis; Gassó, Santiago; Kandler, Konrad; Kasimov, Nikolay; Kavan, Jan; King, James; Koroleva, Tatyana; Krupskaya, Viktoria; Kulmala, Markku; Kusiak, Monika; Lappalainen, Hanna K.; Laska, Michał; Lasne, Jerome; Lewandowski, Marek; Luks, Bartłomiej; McQuaid, James B.; Moroni, Beatrice; Murray, Benjamin; Möhler, Ottmar; Nawrot, Adam; Nickovic, Slobodan; O’Neill, Norman T.; Pejanovic, Goran; Popovicheva, Olga; Ranjbar, Keyvan; Romanias, Manolis; Samonova, Olga; Sanchez-Marroquin, Alberto; Schepanski, Kerstin; Semenkov, Ivan; Sharapova, Anna; Shevnina, Elena; Shi, Zongbo; Sofiev, Mikhail; Thevenet, Frédéric; Thorsteinsson, Throstur; Timofeev, Mikhail; Umo, Nsikanabasi Silas; Uppstu, Andreas; Urupina, Darya; Varga, György; Werner, Tomasz; Arnalds, Olafur; Vukovic Vimic, Ana (Copernicus Publ., 2022)
    Atmospheric chemistry and physics
    Dust particles from high latitudes have a potentially large local, regional, and global significance to climate and the environment as short-lived climate forcers, air pollutants, and nutrient sources. Identifying the locations of local dust sources and their emission, transport, and deposition processes is important for understanding the multiple impacts of high-latitude dust (HLD) on the Earth's systems. Here, we identify, describe, and quantify the source intensity (SI) values, which show the potential of soil surfaces for dust emission scaled to values 0 to 1 concerning globally best productive sources, using the Global Sand and Dust Storms Source Base Map (G-SDS-SBM). This includes 64 HLD sources in our collection for the northern (Alaska, Canada, Denmark, Greenland, Iceland, Svalbard, Sweden, and Russia) and southern (Antarctica and Patagonia) high latitudes. Activity from most of these HLD sources shows seasonal character. It is estimated that high-latitude land areas with higher (SI ≥0.5), very high (SI ≥0.7), and the highest potential (SI ≥0.9) for dust emission cover >1 670 000 km2, >560 000 km2, and >240 000 km2, respectively. In the Arctic HLD region (≥60∘ N), land area with SI ≥0.5 is 5.5 % (1 035 059 km2), area with SI ≥0.7 is 2.3 % (440 804 km2), and area with SI ≥0.9 is 1.1 % (208 701 km2). Minimum SI values in the northern HLD region are about 3 orders of magnitude smaller, indicating that the dust sources of this region greatly depend on weather conditions. Our spatial dust source distribution analysis modeling results showed evidence supporting a northern HLD belt, defined as the area north of 50∘ N, with a “transitional HLD-source area” extending at latitudes 50–58∘ N in Eurasia and 50–55∘ N in Canada and a “cold HLD-source area” including areas north of 60∘ N in Eurasia and north of 58∘ N in Canada, with currently “no dust source” area between the HLD and low-latitude dust (LLD) dust belt, except for British Columbia. Using the global atmospheric transport model SILAM, we estimated that 1.0 % of the global dust emission originated from the high-latitude regions. About 57 % of the dust deposition in snow- and ice-covered Arctic regions was from HLD sources. In the southern HLD region, soil surface conditions are favorable for dust emission during the whole year. Climate change can cause a decrease in the duration of snow cover, retreat of glaciers, and an increase in drought, heatwave intensity, and frequency, leading to the increasing frequency of topsoil conditions favorable for dust emission, which increases the probability of dust storms. Our study provides a step forward to improve the representation of HLD in models and to monitor, quantify, and assess the environmental and climate significance of HLD.
  • Nevanlinna, Heikki (Ilmatieteen laitos - Finnish Meteorological Institute, 2022)
    Raportteja - Rapporter - Reports 2022:4
    Tämä tutkimus käsittelee kansainvälisen polaarivuoden 1932–1933 aikana toimineen Petsamon magneettisen observatorion havaintotuloksia. Mukana on lyhyt katsaus polaarivuoden aikana ja sen jälkeen uudella suomalaisella meteorologisella radiosondilla tehdyistä kokeista 1930-luvun lopulla. Näitä kahta aihepiiriä yhdistää FM Mauri Tommila (1905–1971), joka toimi Petsamon observatorion johtajana ja joka sen jälkeen osallistui merkittävällä panoksella yhdessä Vilho Väisälän kanssa radiosondin kehittelyyn 1934–1939. Sondi valmistui operatiivisen sääpalvelun käyttöön vuonna 1936. Väisälän sondia testattiin vuosina 1937 ja 1939 Huippuvuorilla ja Atlantilla. Molemmissa retkikunnissa Tommila oli mukana. Petsamon observatorio oli yksi Suomen geofysikaalisen tiedeyhteisön kontribuutioista polaarivuoden tutkimus- ja havainto-ohjelmiin. Sen päätehtävä oli rekisteröidä maan magneettikentän vaihteluja jatkuvasti toimivilla laitteilla ajan havaintokäytäntöjen mukaisesti. Päävastuu observatorion toiminnoista oli Suomalaisella Tiedeakatemialla ja sen Sodankylän observatoriolla. Tarvittavat rekisteröintilaitteet oli hankittu Tanskan meteorologiselta laitokselta ja ne edustivat aikansa mittausteknologista huippua. Observatorio oli myös Ilmatieteen laitoksen tärkeä havainto- ja koeasema polaarivuoden ohjelmassa. Polaarivuoden havainto-ohjelman ja laiterakennuksien suunnittelun olivat tehneet Sodankylän magneettisen observatorion johtaja Eyvind Sucksdorff (1899–1955) ja Ilmatieteen laitoksen johtaja Jaakko Keränen (1883–1979). Keränen oli Sodankylän magneettisen observatorion ensimmäinen johtaja 1913–1917 (Nevanlinna, 2014). Petsamon observatorio sijaitsi lähellä Pohjoisen jäämeren rannikkoa Petsamojoen suistossa. Petsamo on nykyään Venäjän hallinnoimaa aluetta. Petsamon magneettinen observatorio oli toiminnassa 13 kuukautta 1.8.1932–31.8.1933 välisen ajan. Rekisteröintitulokset tieteelliseen käyttöön muodostuivat alan käytännön mukaisista magneettikentän eri komponenttien tuntikeskiarvoista. Mauri Tommila julkaisi tulokset taulukkojen muodossa yhdessä tarvittavien metadatatietojen kanssa kansainväliseen tutkimuskäyttöön (Tommila, 1937a). Tässä julkaisussa on yhteenveto tehdyistä magneettikentän mittauksista. Vertailu Sodankylässä tehtyihin samanaikaisiin rekisteröintituloksiin osoittavat, että Petsamon observatorion rekisteröintitulokset ovat olleet korkeatasoisia ja että julkaistu aineisto on tieteellisiin analyyseihin käyttökelpoista. Kaikki Suomen vanhat historialliset magneettiset rekisteröintiaineistot ovat nyt digitoitu Petsamon aineiston valmistuttua. Vanhin niistä on Helsingin magneettisen observatorion havainnot 1844–1910. Petsamon observatorioon rinnastuu Sodankylän magneettiseen ja meteorologiseen observatorioon polaarivuodelta 1882– 1883. Myös sen magneettiset ja meteorologiset havainnot uudelleen julkaisu ja digitoitu (Nevanlinna, 2017a).
  • Slater, Jessica; Coe, Hugh; McFiggans, Gordon; Tonttila, Juha; Romakkaniemi, Sami (Copernicus Publ., 2022)
    Atmospheric chemistry and physics
    Beijing suffers from poor air quality, particularly during wintertime haze episodes when concentra tions of PM2.5 (particulate matter with a diameter < 2.5 µm) can peak at > 400 µg m−3. Black carbon (BC), an aerosol which strongly absorbs solar radiation, can make up to 10 % of PM2.5 in Beijing. BC is of interest due to its climatic and health impacts. BC has also been found to impact planetary boundary layer (PBL) meteorology. Through interacting with radiation and altering the thermal profile of the lower atmosphere, BC can either suppress or enhance PBL development depending on the properties and altitude of the BC layer. Previous research assessing the impact of BC on PBL meteorology has been investigated through the use of regional models, which are limited both by resolution and the chosen boundary layer schemes. In this work, we apply a high-resolution model (UCLALES-SALSA) that couples an aerosol and radiative transfer model with large-eddy simulation (LES) to quantify the impact of BC at different altitudes on PBL dynamics using conditions from a specific haze episode which occurred from 1–4 December 2016 in Beijing. Results presented in this paper quantify the heating rate of BC at various altitudes to be between 0.01 and 0.016 K/h per µg/m3 of BC, increasing with altitude but decreasing around PBL top. Through utilising a high-resolution model which explicitly calculates turbulent dynamics, this paper showcases the impact of BC on PBL dynamics both within and above the PBL. These results show that BC within the PBL increases maximum PBL height by 0.4 % but that the same loading of BC above the PBL can suppress PBL height by 6.5 %. Furthermore, when BC is present throughout the column, the impact of BC suppressing PBL development is further maximised, with BC causing a 17 % decrease in maximum PBL height compared to only scattering aerosols. Assessing the impact of these opposite effects, in this paper, we present a mechanism through which BC may play a prominent role in the intensity and longevity of Beijing’s pollution episodes.
  • Boutle, Ian; Angevine, Wayne; Bao, Jian-Wen; Bergot, Thierry; Bhattacharya, Ritthik; Bott, Andreas; Ducongé, Leo; Forbes, Richard; Goecke, Tobias; Grell, Evelyn; Hill, Adrian; Igel, Adele L.; Kudzotsa, Innocent; Lac, Christine; Maronga, Bjorn; Romakkaniemi, Sami; Schmidli, Juerg; Schwenkel, Johannes; Steeneveld, Gert-Jan; Vié, Benoît (Copernicus Publ., 2022)
    Atmospheric chemistry and physics
    An intercomparison between 10 single-column (SCM) and 5 large-eddy simulation (LES) models is presented for a radiation fog case study inspired by the Local and Non-local Fog Experiment (LANFEX) field campaign. Seven of the SCMs represent single-column equivalents of operational numerical weather prediction (NWP) models, whilst three are research-grade SCMs designed for fog simulation, and the LESs are designed to reproduce in the best manner currently possible the underlying physical processes governing fog formation. The LES model results are of variable quality and do not provide a consistent baseline against which to compare the NWP models, particularly under high aerosol or cloud droplet number concentration (CDNC) conditions. The main SCM bias appears to be toward the overdevelopment of fog, i.e. fog which is too thick, although the inter-model variability is large. In reality there is a subtle balance between water lost to the surface and water condensed into fog, and the ability of a model to accurately simulate this process strongly determines the quality of its forecast. Some NWP SCMs do not represent fundamental components of this process (e.g. cloud droplet sedimentation) and therefore are naturally hampered in their ability to deliver accurate simulations. Finally, we show that modelled fog development is as sensitive to the shape of the cloud droplet size distribution, a rarely studied or modified part of the microphysical parameterisation, as it is to the underlying aerosol or CDNC.
  • Harni, Sami D.; Saarikoski, Sanna; Kuula, Joel; Helin, Aku; Aurela, Minna; Niemi, Jarkko V.; Kousa, Anu; Rönkkö, Topi; Timonen, Hilkka (Pergamon., 2023)
    Atmospheric environment
    Particle size distribution is a major factor in the health and climate effects of ambient aerosols, and it shows a large variation depending on the prevailing atmospheric emission sources. In this work, the particle number size distributions of ambient air were investigated at a suburban detached housing area in northern Helsinki, Finland, during a half-year period from winter to summer of 2020. The measurements were conducted with a scanning mobility particle sizer (SMPS) with a particle size range of 16–698 nm (mobility diameter), and the events with a dominant particle source were identified systematically from the data based on the time of the day and different particle physical and chemical properties. During the measurement period, four different types of events with a dominant contribution from either wood-burning (WB), traffic (TRA), secondary biogenic (BIO), or long-range transported (LRT) aerosol were observed. The particle size was the largest for the LRT events followed by BIO, WB, and TRA events with the geometric mean diameters of 72, 62, 57, and 41 nm, respectively. BIO and LRT produced the largest particle mode sizes followed by WB, and TRA with the modes of 69, 69, 46, and 25 nm, respectively. Each event type had also a noticeably different shape of the average number size distribution (NSD). In addition to the evaluation of NSDs representing different particle sources, also the effects of COVID-19 lockdown on specific aerosol properties were studied as during the measurement period the COVID-19 restrictions took place greatly reducing the traffic volumes in the Helsinki area in the spring of 2020. These restrictions had a significant contribution to reducing the concentrations of NOx and black carbon originating from fossil fuel combustion concentration, but insignificant effects on other studied variables such as number concentration and size distribution or particle mass concentrations (PM1, PM2.5, or PM10).
  • Manninen, Terhikki; Jääskeläinen, Emmihenna; Siljamo, Niilo; Riihelä, Aku; Karlsson, Karl-Göran (Copernicus Publications, 2022)
    Atmospheric measurement techniques
    This paper describes a new method for cloudcorrecting observations of black-sky surface albedo derived using the Advanced Very High Resolution Radiometer (AVHRR). Cloud cover constitutes a major challenge for surface albedo estimation using AVHRR data for all possible conditions of cloud fraction and cloud type with any land cover type and solar zenith angle. This study shows how the new cloud probability (CP) data to be provided as part of edition A3 of the CLARA (CM SAF cLoud, Albedo and surface Radiation dataset from AVHRR data) record from the Satellite Application Facility on Climate Monitoring (CM SAF) project of EUMETSAT can be used instead of traditional binary cloud masking to derive cloud-free monthly mean surface albedo estimates. Cloudy broadband albedo distributions were simulated first for theoretical cloud distributions and then using global cloud probability (CP) data for 1 month. A weighted mean approach based on the CP values was shown to produce very-high-accuracy black-sky surface albedo estimates for simulated data. The 90 % quantile for the error was 1.1 % (in absolute albedo percentage) and that for the relative error was 2.2 %. AVHRR-based and in situ albedo distributions were in line with each other and the monthly mean values were also consistent. Comparison with binary cloud masking indicated that the developed method improves cloud contamination removal.
  • Van Mai, Khiem; Laurila, Terhi K.; Hoang, Lam Phuc; Duc Du, Tien; Mäkelä, Antti; Kiesiläinen, Sami (MDPI AG, 2022)
    Within a meteorological capacity building project in Vietnam, lightning location data and manual (human-observed) thunderstorm day observations were analyzed for the period 2015–2019. The lightning location dataset, based on the global lightning detection system Vaisala GLD360, consists of a total of 315,522,761 lightning strokes. The results indicate that, on average, 6.9 million lightning flashes per year occur in the land areas of Vietnam; this equals a lightning flash density of 20 flashes km−2 yr−1. The largest average annual flash density values occur in three regions in North, Central and South Vietnam. The majority of lightning occurs in the monsoon season (April–September), peaking in May, while in October–March, the lightning activity is very modest. During individual intense thunderstorm days, the flash density may exceed 12 flashes km−2 day−1. Thunderstorms in Central Vietnam are generally more intense, i.e., more lightning is expected on average per one thunderstorm day in Central Vietnam than in other regions. This study is a continuation of several years of meteorological capacity building in Vietnam, and the results suggest that large socio-economic benefits can be received by understanding the local thunderstorm climatology in high detail, especially in a country such as Vietnam, where lightning causes substantial socio-economic losses annually.
  • Huard, David; Fyke, Jeremy; Capellán‐Pérez, Iñigo; Matthews, H. Damon; Partanen, Antti‐Ilari (John Wiley & Sons, 2022)
    The climate scenarios that form the basis for current climate risk assessments have no assigned probabilities, and this impedes the analysis of future climate risks. This paper proposes an approach to estimate the probability of carbon dioxide (CO2) concentration scenarios used in key climate change modeling experiments. It computes the CO2 emissions compatible with the concentrations prescribed by Coupled Model Intercomparison Project Phase 5 (CMIP5) and CMIP6 experiments. The distribution of these compatible cumulative emissions is interpreted as the likelihood of future emissions given a concentration pathway. Using Bayesian analysis, the probability of each pathway can be estimated from a probabilistic sample of future emissions. The approach is demonstrated with five probabilistic CO2 emission simulation ensembles from four Integrated Assessment Models (IAM), leading to independent estimates of the likelihood of the CO2 concentration of Representative Concentration Pathways (RCP) and Shared Socioeconomic Pathways (SSP). Results suggest that SSP5-8.5 is unlikely for the second half of the 21st century, but offer no clear consensus on which of the remaining scenarios is most likely. Estimates of likelihoods of CO2 concentrations associated with RCP and SSP scenarios are affected by sampling errors, differences in emission sources simulated by the IAMs, and a lack of a common experimental framework for IAM simulations. These shortcomings, along with a small IAM ensemble size, limit the applicability of the results presented here. Novel joint IAM and the Earth System Model experiments are needed to deliver actionable probabilistic climate risk assessments.
  • Vepsäläinen, Sampo; Calderón, Silvia M.; Malila, Jussi; Prisle, Nønne L. (Copernicus Publ., 2022)
    Atmospheric chemistry and physics
    Surface active compounds (surfactants) are frequently found in atmospheric aerosols and droplets. As they adsorb to the surfaces of microscopic systems, surfactants can decrease aqueous surface tension and simultaneously deplete the bulk concentration. These processes may influence the activation of aerosols into cloud droplets and investigation of their role in cloud microphysics has been ongoing for decades. In this work, we have used six different models documented in the literature to represent surface activity in Köhler calculations of cloud droplet activation for particles consisting of one of three moderately surface active organics (malonic, succinic or glutaric acid) mixed with ammonium sulfate in varying mass ratios. For each of these organic acids, we find that the models predict comparable activation properties at small organic mass fractions in the dry particles, despite large differences in the predicted degree of bulk-to-surface partitioning. However, differences between the model predictions for the same dry particles regarding both the critical droplet diameters and supersaturations increase with the organic fraction in the particles. Comparison with available experimental data shows that models assuming complete bulk-to-surface partitioning of the moderately surface active component (total depletion of the bulk) do not adequately represent the droplet activation of particles with high organic mass fractions. When reduced droplet surface tension is also considered, these predictions somewhat improve. Models that consider partial bulk-to-surface partitioning of surface active components yield results comparable to experimental supersaturation data, even at high organic mass fractions in the particles, but predictions of the degree of organic bulk–surface partitioning strongly differ. This work highlights the need to use a thermodynamically consistent model framework to treat the surface activity of atmospheric aerosols and for firm experimental validation of model predictions across a wide range of droplet states relevant to the atmosphere.
  • Calderón, Silvia M.; Tonttila, Juha; Buchholz, Angela; Joutsensaari, Jorma; Komppula, Mika; Leskinen, Ari; Hao, Liqing; Moisseev, Dmitri; Pullinen, Iida; Tiitta, Petri; Xu, Jian; Virtanen, Annele; Kokkola, Harri; Romakkaniemi, Sami (Copernicus Publ., 2022)
    Atmospheric chemistry and physics
    We carried out a closure study of aerosol-cloud interactions during stratocumulus formation using a large eddy simulation model UCLALES-SALSA and observations from the 2020 cloud sampling campaign at the Puijo SMEAR IV station in Kuopio, Finland. The unique observational setup combining in situ and cloud remote sensing measurements allowed a closer look into the aerosol size-composition dependence of droplet activation and droplet growth in turbulent boundary layer driven by surface forcing and radiative cooling. UCLALES-SALSA uses spectral bin microphysics for aerosols and hydrometeors and incorporates a full description of their interactions into the turbulent-convective radiation-dynamical model of stratocumulus. Based on our results, the model successfully described the probability distribution of updraft velocities and consequently the size dependency of aerosol activation into cloud droplets, and further recreated the size distributions for both interstitial aerosol and cloud droplets. This is the first time such a detailed closure is achieved not only accounting for activation of cloud droplets in different updrafts, but also accounting for processes evaporating droplets and drizzle production through coagulation-coalescence. We studied two cases of cloud formation, one diurnal (24 September 2020) and one nocturnal (31 October 2020), with high and low aerosol loadings, respectively. Aerosol number concentrations differ more than 1 order of magnitude between cases and therefore, lead to cloud droplet number concentration (CDNC) values which range from less than 100cm-3 up to 1000cm-3. Different aerosol loadings affected supersaturation at the cloud base, and thus the size of aerosol particles activating to cloud droplets. Due to higher CDNC, the mean size of cloud droplets in the diurnal-high aerosol case was lower. Thus, droplet evaporation in downdrafts affected more the observed CDNC at Puijo altitude compared to the low aerosol case. In addition, in the low aerosol case, the presence of large aerosol particles in the accumulation mode played a significant role in the droplet spectrum evolution as it promoted the drizzle formation through collision and coalescence processes. Also, during the event, the formation of ice particles was observed due to subzero temperature at the cloud top. Although the modeled number concentration of ice hydrometeors was too low to be directly measured, the retrieval of hydrometeor sedimentation velocities with cloud radar allowed us to assess the realism of modeled ice particles. The studied cases are presented in detail and can be further used by the cloud modellers to test and validate their models in a well-characterized modelling setup. We also provide recommendations on how increasing amount of information on aerosol properties could improve the understanding of processes affecting cloud droplet number and liquid water content in stratiform clouds.

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