Ilmatieteen laitos

Recent Submissions

  • Tsuruta, Aki (Finnish Meteorological Institute, 2017)
    Finnish Meteorological Institute Contributions 141
    Ensemble Kalman filter (EnKF) is a useful Bayesian inverse modelling method to make inference of the states of interest from observations, especially in non-linear systems with a large number of states to be estimated. This thesis presents an application of EnKF in estimation of global and regional methane budgets, where methane fluxes are inferred from atmospheric methane concentration observations. The modelling system here requires a highly non-linear atmospheric transport model to convert the state space on to the observation space, and an optimization in both spatial and temporal dimensions is desired. Methane is an important greenhouse gas, strongly influenced by anthropogenic activities, whose atmospheric concentration increased more than twice since pre-industrial times. Although its source and sink processes have been studied extensively, the mechanisms behind the increase in the 21st century atmospheric methane concentrations are still not fully understood. In this thesis, contributions of anthropogenic and natural sources to the increase in the atmospheric methane concentrations are studied by estimating the global and regional methane fluxes from anthropogenic and biospheric sources for the 21st century using an EnKF based data assimilation system (CarbonTracker Europe-CH4; CTE-CH4). The model was evaluated using assimilated in situ atmospheric concentration observations and various non-assimilated observations, and the model sensitivity to several setups and inputs was examined to assess the consistency of the model estimates. The key findings of this thesis include: 1) large enough ensemble size, appropriate prior error covariance, and good observation coverage are important to obtain consistent and reliable estimates, 2) CTE-CH4 was able to identify the locations and sources of the emissions that possibly contribute significantly to the increase in the atmospheric concentrations after 2007 (the Tropical and extra Tropical anthropogenic emissions), 3) Europe was found to have an insignificant or negative influence on the increase in the atmospheric CH4 concentrations in the 21st century, 4) CTE-CH4 was able to produce flux estimates that are generally consistent with various observations, but 5) the estimated fluxes are still sensitive to the number of parameters, atmospheric transport and spatial distribution of the prior fluxes.
  • Svensson, Jonas (Finnish Meteorological Institute, 2017)
    Finnish Meteorological Institute Contributions 140
    Snow and ice are essential components of the Earth system, modulating the energy budget by reflecting sunlight back into the atmosphere, and through its importance in the hydrological cycle by being a reservoir for fresh water. Light-absorbing impurities (LAI), such as black carbon (BC) and mineral dust (MD), have a unique role in influencing the reflectance of the cryosphere. Deposition of the anthropogenic and natural LAI constituents onto these bright surfaces initiates powerful albedo feedbacks that will accelerate melt. This is important globally, but especially for regions such as the Arctic and the Himalaya. In this thesis, observations from both ambient and laboratory experiments are presented. The overarching research goal has been to better understand the climatic effect of LAI on snow. More specifically, an emphasis has been placed on exploring the process-level interactions between LAI and snow, which will enable better comprehension of LAI affecting the cryosphere. Key findings in this thesis involves the investigations on the horizontal variability of BC concentrations in the surface snow that indicate a larger variability on the order of meter scale at a pristine Arctic site compared to a polluted site nearby a major urban area. In outdoor experiments, where LAI were used to artificially dope natural snow surfaces, the snow albedo was observed to decrease following LAI deposition. The albedo decrease was on the same order as in situ measurements of LAI and albedo conducted elsewhere. As snow melted during the experiment, the snow density was observed to decrease with increasing LAI concentration, while this effect was not observed in non-melting snow. The water retention capacity in melting snow is likely to be decreased by the presence of LAI. Measurements examining the absorption of BC indicate that BC particles in the snow have less absorbing potential compared to BC particles generated in the laboratory. The LAI content of snow pit investigations from two glaciers in the Sunderdhunga valley, northern India, an area not previously examined for LAI, presented high BC and MD content, affecting the radiative balance of the glacier snow. At different points, MD may be greater than BC in absorbing light at the snow surface. A continued monitoring of LAI in the cryosphere, both on the detailed scale explored here, as well as on the larger modelling perspective is needed in order to understand the overall response of the cryosphere to climate change.
  • Päivärinta, Sanna-mari (Finnish Meteorological Institute, 2017)
    Finnish Meteorological Institute Contributions 136
    Odd nitrogen (NOx = N + NO + NO2) in the polar regions is mainly produced in the upper atmosphere through ionization processes by solar extreme ultraviolet radiation, soft X-rays and high energy particles originating from the space. During periods of high geomagnetic activity, normally close to the solar maximum, energetic particle precipitation (EPP) provides an in-situ source of NOx also in the middle atmosphere. Understanding the behaviour of NOx in the middle atmosphere is of great importance due to its capability to act as a catalyst in chemical reaction cycles destroying ozone in the stratosphere. This work considers EPP in the form of solar proton events (SPEs). Atmospheric dynamics play an important role in determining the distributions of long-lived trace gases in the middle atmosphere. The main loss mechanism for NOx is photolysis at the upper stratospheric and mesospheric altitudes, leading to long photochemical lifetime of NOx during the dark polar winter. NOx in the middle atmosphere, also if produced in-situ due to SPEs, is therefore affected by atmospheric dynamics, and transported from the mesosphere-lower hermosphere (MLT) region down to the middle atmosphere. This descent phenomenon can be intensified in the aftermath of sudden stratospheric warmings (SSWs), which are dynamical phenomena able to affect a wide range of altitudes in the Northern polar region atmosphere. The enhanced downward transport of NOx can thus strengthen the NOx-ozone connection in the stratosphere. In this work we used both space born observations from several satellite instruments and a chemistry transport model in the examination of the SSW and SPE caused effects in the stratosphere and mesosphere. The scientific objectives of this work were to find out the individual and combined effects of SSWs and SPEs on the NOx and ozone balance in the Northern middle atmosphere, and assess the relative contributions of dynamics (SSWs) and in-situ production of NOx (SPEs) on ozone in the stratosphere. The results showed dramatic increases in NOx in the middle atmosphere, even by a factor of 50, following both periods of enhanced NOx descent in connection with SSWs and in-situ production of NOx due to SPEs. A clear long-term (order of months) decrease in stratospheric ozone (10-90 %), coinciding with the enhanced amounts of NOx, was evident and affected mostly by dynamics in the upper stratosphere. The results of this work emphasize the importance of in-situ production of NOx (SPEs) on the ozone balance in the upper stratosphere, but also the key role of dynamics (SSWs) in transporting the SPE effect to even lower altitudes and its capability to strengthen the effect.
  • Komppula, Birgitta; Waldén, Jari; Lusa, Kaisa; Kyllönen, Katriina; Saari, Helena; Vestenius, Mika; Salmi, Jatta; Latikka, Jenni (Finnish Meteorological Institute, 2017)
    Raportteja - Rapporter - Reports 2017:6
    Suomen ilmanlaadun seurantaa säätelevät suurelta osin EU:n ilmanlaatua koskevat direktiivit. Ilman epäpuhtauksien pitoisuuksia säädellään sitovien raja-arvojen ja tavoitearvojen avulla. Myös kansalliset ohjearvot ovat edelleen voimassa ja niitä käytetään suunnittelun tukena, mutta niiden merkitys on vähenemässä. Raja-arvoja valvoviksi asemiksi kutsutaan niitä ilmanlaadun mittausasemia, jotka täyttävät ilmanlaatudirektiivien kriteerit ja joiden pitoisuustiedot toimitetaan EU:lle. Rajaarvopitoisuuksia valvovien mittausasemien lisäksi ilmanlaatua seurataan mittausverkoissa laajalti erilaisista paikallisista tarpeista, mikä on ollut aikanaan lähtökohta useimpien ilmanlaatumittausten aloittamiselle. Ilmanlaatua seurataan ensisijaisesti hyvän ilmanlaadun turvaamiseksi paikallisille asukkaille ja ympäristölle. Ilmanlaatua mitataan lisäksi muun muassa yksittäisten päästölähteiden vaikutusten arvioimiseksi, asukkaiden valitusten vuoksi, ympäristölupaehtojen täyttämiseksi sekä jatkuvan ilmanlaadun seurannan tarvetta arvioitaessa. Tämä ohje koskee ilmanlaadun mittaamista osana ilmanlaadun seurantaa. Ohjeessa käsitellään ilmanlaatulainsäädäntöä, mittaustarpeen arviointia, mittausten suunnittelua, tekemistä ja laadunvarmennustoimenpiteitä, laatujärjestelmän sisältöä, raportointia sekä tiedottamista. Ohjeen tarkoituksena on kehittää mittausten laatua, luotettavuutta, edustavuutta ja vertailtavuutta sekä luoda edellytyksiä ilmanlaadun mittaustulosten monipuoliselle hyödyntämiselle. Ilmatieteen laitos päivitti ilmanlaadun mittausohjetta edellisen kerran vuonna 2004 ja nyt mittausohjetta on edelleen laajennettu ja päivitetty ajan tasalle.
  • Salminen, Miia (Finnish Meteorological Institute, 2017)
    Finnish Meteorological Institute Contributions 139
    Monitoring of snow cover in northern hemisphere is highly important for climate research and for operational activities, such as those related to hydrology and weather forecasting. The appearance and melting of seasonal snow cover dominate the hydrological and climatic patterns in the boreal and arctic regions. Spatial variability (in particular during the spring and autumn transition months) and long-term trends in global snow cover distribution are strongly interconnected to changes in Earth System (ES). Satellite data based estimates on snow cover extent are utilized e.g. in near-real-time hydrological forecasting, water resource management and to construct long-term Climate Data Records (CDRs) essential for climate research. Information on the quantitative reliability of snow cover monitoring is urgently needed by these different applications as the usefulness of satellite data based results is strongly dependent on the quality of the interpretation. This doctoral dissertation investigates the factors affecting the reliability of snow cover monitoring using optical satellite data and focuses on boreal regions (zone characterized by seasonal snow cover). Based on the analysis of different factors relevant to snow mapping performance, the work introduces a methodology to assess the uncertainty of snow cover extent estimates, focusing on the retrieval of fractional snow cover (within a pixel) during the spring melt period. The results demonstrate that optical remote sensing is well suited for determining snow extent in the melting season and that the characterizing the uncertainty in snow estimates facilitates the improvement of the snow mapping algorithms. The overall message is that using a versatile accuracy analysis it is possible to develop uncertainty estimates for the optical remote sensing of snow cover, which is a considerable advance in remote sensing. The results of this work can also be utilized in the development of other interpretation algorithms. This thesis consists of five articles predominantly dealing with quantitative data analysis, while the summary chapter synthesizes the results mainly in the algorithm accuracy point of view. The first four articles determine the reflectance characteristics essential for the forward and inverse modeling of boreal landscapes (forward model describes the observations as a function of the investigated variable). The effects of snow, snow-free ground and boreal forest canopy on the observed satellite scene reflectance are specified. The effects of all the error components are clarified in the fifth article and a novel experimental method to analyze and quantify the amount of uncertainty is presented. The five articles employ different remote sensing and ground truth data sets measured and/or analyzed for this research, covering the region of Finland and also applied to boreal forest region in northern Europe.
  • Oikkonen, Annu (Finnish Meteorological Institute, 2017)
    Finnish Meteorological Institute Contributions 138
    The state of the sea ice cover results from an interplay between thermodynamics and dynamics. Changes in the ice cover further affect the way in which the ice responds to forcing, both thermodynamic and dynamic. This thesis discusses several aspects of sea ice thermodynamics and dynamics, and their contribution to the evolution of ice pack, and particularly to changes in the Arctic sea ice cover. The main focus is on the ice dynamics in different types of ice zones and under different conditions, which also enables the examination of the impact of thermodynamic forcing on sea ice dynamics. Changes in the Arctic sea ice thickness distribution during the period 1975-2000 are studied in detail, and the contribution of thermodynamics and dynamics as driving forcing is discussed. The results show that the shape of the sea ice thickness distribution has changed: the peak of the distribution has generally narrowed and shifted towards thinner ice. A prevalent feature is the loss of thick, mostly deformed ice, which has had a significant role in the decrease in the mean and modal ice thickness. The results also show a decrease in the seasonal variability of the mean ice thickness, but with strong regional differences. Also, the regional variability of the sea ice thickness has decreased, since the thinning has been the most pronounced in regions which formerly had the thickest ice cover. The observed changes in the regional ice draft distributions cannot be explained by local warming of the atmosphere, but changes in the ice drift patterns have had an essential impact. These results emphasize the importance of the description of sea ice dynamics in the models. Sea ice dynamics, and especially deformation, strongly affect the evolution of ice volume and properties of ice cover. There has still been a need for better understanding of the highly local and intermittent deformation process, as well as its variability that rises from different types of conditions and regions. Several aspects of these questions are covered in this thesis. With coastal and ship radar images, the study of the length scale dependency of sea ice deformation rate is extended to smaller length scales (from 100 m to 10 km) and time scales (from 10 min to 24 h) than were previously possible. Sea ice deformation rate is shown to exhibit a power law with respect to both length scale and time scale at all the scales covered. Both the overall deformation rate and the length scale dependency of deformation rate are found to depend strongly on the time scale considered. Small scale deformation is studied in different type of ice regions (coastal boundary zone, compact Arctic ice pack and marginal ice zone), and under different weather conditions. One of the key findings is the connection between air temperature and deformation rate: during warm days deformation rates are generally higher than during cold days. The deformation rate is found to respond to changes in air temperature in a time scale of days, which is clearly faster than previously assumed. This response is most likely connected to the effectiveness of the healing process. However, despite of the most effective healing during the coldest winter, the previously damaged areas are found to remain the weak points in the ice cover. This confirms that the deformation history is an important factor in determining how the ice cover responds to dynamic forcing.
  • Huttunen, Jani (Finnish Meteorological Institute, 2017)
    Finnish Meteorological Institute Contributions 135
    Aerosols affect the climate both directly and indirectly. The direct effect comes from their influence on the radiation balance by scattering and absorption of solar radiation, while the indirect effect is based on the ways in which aerosols interact via clouds. Currently the total anthropogenic aerosol forcing includes one of the main uncertainties in the assessment of human induced climate change. The aerosol direct radiative effect (ADRE) can be simulated with either the radiative transfer modelling or estimated with solar radiation and aerosol amount measurements. Both approaches include significant uncertainties and this thesis focuses on the uncertainties on the measurement based estimation of ADRE and the uncertainties therein. The main scientific objectives of this thesis are to seek answers to the following four questions: 1) are the machine learning algorithms better than the a traditional lookup table (LUT) approach in estimating aerosol load (aerosol optical depth, AOD)?; 2) what is the role of water vapor (WVC) variability in the measurementbased regression method used to estimate the surface ADRE?; 3) how well do the radiative transfer codes, typically used in global aerosol models, agree?; 4) what is the impact of typically neglected diurnal aerosol variability in ADRE estimation? The results show that: 1) the machine learning algorithms are able to provide AOD more accurately than the LUT approach for conditions of varying aerosol optical properties, since in the LUT approach the aerosol model (e.g. single scattering albedo, asymmetry factor) needs to be fixed in advance. 2) It was found that covariability of AOD and WVC can have an influence in ADRE estimates, when using groundbased measurements of surface solar radiation and AOD. This has not been taken into account previously, but needs to be considered when these methods are applied. 3) The model intercomparison study, in which the models estimated the radiative fluxes for the same atmospheric states, revealed that there is relatively large diversity between models regarding the results from their radiative transfer modelling. 4) The main conclusion from the study focusing on the impact of systematic diurnal AOD cycles in aerosol direct radiative effect, was that even a notable diurnal change in AOD does not typically affect the 24h-average ADRE significantly.
  • Hippi, Marjo; Hartonen, Sari; Hirvonen, Mikko (Finnish Meteorological Institute, 2017)
    Raportteja - Rapporter- Reports 3:2017
    Työmatkatapaturmia tapahtuu kävellen talvisin huomattavasti enemmän kuin kesäisin, ja yksittäiset liukkaimmat päivät näkyvät selvinä piikkeinä kuvaajissa, joissa on esitetty päivittäiset liukastumisten kokonaismäärät. Liukastumisonnettomuudet aiheuttavat vuosittain merkittävät taloudelliset kustannukset sairaanhoidon ja sairauspoissaolojen takia. Projektin tavoitteena oli vähentää talvisin ulkona tapahtuvia liukastumisonnettomuuksia informoimalla työnsä puolesta ulkona liikkuvia tulevasta liukkaasta kelistä, jolloin he voisivat varautua liukkauteen esimerkiksi pitävillä kengillä, liukuesteillä tai varaamalla enemmän aikaa matkaan. Kun kerrotaan liukastumistapaturmista ja niiden ehkäisystä, se saa työyhteisön toivottavasti suhtautumaan liukastumistapaturmien riskeihin entistä vakavammin. Projektissa olivat mukana Ilmatieteen laitos, Työterveyslaitos (TTL) ja Posti (entiseltä nimeltään Itella). Vaisalalta ostettiin kaksi DSC111-mittaria projektin käyttöön ja niillä tutkittiin, kuinka hyvin laite määrittää kevyenliikenteen väylien liukkautta. Ilmatieteen laitos kehitti kelivaroitusmallia ja liukastumisvaroituksia loppukäyttäjille. Työterveyslaitos teki liukkaustutkimuksia kehittämällään liukkausmittarilla. Postin työntekijöitä toimi liukkausvaroituspalvelun testikäyttäjinä, ja he tekivät myös omia havaintoja liukkaista paikoista ja päivistä. Projekti kesti vuodesta 2013 vuoteen 2016 kattaen kolme täyttä talvijaksoa. Tavoitteena oli päästä testaamaan Ilmatieteen laitoksen kelivaroitusmallia ja varoituspalvelua useamman talvikauden aikana erilaisten talvikelien vallitessa.
  • Hoilijoki, Sanni (Finnish Meteorological Institute, 2017)
    Finnish Meteorological Institute Contributions 132
    This thesis investigates interactions between solar wind and the magnetosphere of the Earth using two global magnetosphericsimulation models, GUMICS-4 and Vlasiator, which are both developed in Finland. The main topic of the thesis is magnetic reconnection at the dayside magnetopause, its drivers and global effects. Magnetosheath mirror mode waves and their evolution, identification and impacts on the local reconnection rates at the magnetopause are also discussed. This thesis consists of four peer-reviewed papers and an introductory part. GUMICS-4 is a magnetohydrodynamic model solving plasma as a single magnetized fluid. Vlasiator is the world’s first global magnetospheric hybrid-Vlasov simulation model, which solves the motion of ions by describing them as velocity distribution functions, whereas electrons are described as a charge neutralizing fluid. Vlasiator is able to solve ion scale physics in a global scale simulation. However, it is computationally heavy and the global simulations are currently describing Earth’s magnetosphere only in two spatial dimensions, whereas the velocity space is three dimensional. This thesis shows that magnetic reconnection at the dayside magnetopause is controlled by several factors. The impact of dipole tilt angle and sunward component of the interplanetary magnetic field on magnetopause reconnection is investigated with a set of GUMICS-4 simulations. Using Vlasiator simulations, this thesis shows that local reconnection rate is highly variable even during steady solar wind and correlates well with an analytical model for 2D asymmetric reconnection. It is also shown that the local reconnection rate is affected by local variations in the magnetosheath plasma. Fluctuations in the magnetosheath parameters near X-lines are partly generated by mirror mode waves that are observed to grow in the quasi-perpendicular magnetosheath. These results show that that the local reconnection rate at the X-lines is affected not only by the fluctuations in the inflow parameters but also by reconnection at nearby X-lines. Outflow from stronger X-lines pushes against the weaker ones and might ultimately suppress reconnection in the weaker X-lines. Magnetic islands, 2D representations of FTEs, form between X-lines in the Vlasiator simulations. FTEs propagate along the dayside magnetopause driving bow waves in the magnetosheath. The bow waves propagate upstream all the way to the bow shock causing bulges in the shock, from which solar wind particles can reflect back to the solar wind causing local foreshocks. The overall conclusion of this thesis is that the ion scale kinetic physics is important to accurately model the solar wind – magnetosheath – magnetopause interactions. Vlasiator results show a strong scale-coupling between ion and global scales: global scale phenomena have an impact on the local physics and the local phenomena may have unexpected impacts on the global dynamics of the magnetosphere. Neglecting the global scales in local ion scale simulations and vice versa may therefore lead to incomplete description of the solar wind – magnetosphere interactions.
  • Jääskeläinen, Emmihenna; Manninen, Terhikki; Tamminen, Johanna; Laine, Marko (Finnish Meteorological Institute, 2017)
    Raportteja - Rapporter - Reports 2:2017
    In the Satellite Application Facility on Climate Monitoring (CM SAF) project, financially supported by EUMETSAT, the 34-year long (1982-2015) broadband albedo time series CLARA-A2 SAL (the Surface ALbedo from the CM SAF cLoud, Albedo and RAdiation data record, second version) was produced from Advanced Very High Resolution Radiometer (AVHRR) measurements. CLARA-A2 SAL data record uses a Simplified Method for Atmospheric Correction algorithm SMAC for correcting for atmospheric effects. Aerosol optical depth (AOD) is the main input of the algorithm. Because there were no global AOD time series for the whole needed time period (1982-2015), the AOD-related time series were constructed, and the method for calculating it is described in this report.
  • Suomi, Irene (Finnish Meteorological Institute, 2017)
    Finnish Meteorological Institute Contributions 134
    Wind gusts, which are short duration (typically 3 s) wind speed maxima, are representative of the extreme wind conditions. They are very important for human activity, because the strongest gusts associated with storms are the most significant single cause of natural hazards. The impact of wind gusts on different structures depends on the characteristics of each structure. For example for wind energy, it is important to know both the probability of extreme maximum gusts in time scales of decades for the design of power plants and in the shorter term to support wind turbine operations. For wind gust forecasting it is essential to have reliable wind gust observations. Traditionally, observations have only been available from weather stations here the wind is usually measured at a reference height of 10 m. For wind energy, information is needed at greater heights, as the hub heights of the largest turbines extend even above 150 m. The main aim of this work has been to investigate wind gusts across the entire atmospheric boundary layer based on observations from tall meteorological masts as well as applying new measurement methods developed in this dissertation. The novel methods are based on turbulence measurements taken onboard a research aircraft and by a Doppler lidar. The research aircraft can fly long distances in a short time, so the measured wind speeds do not represent wind speed variation in time but they are a function of flight distance. The new method developed in this dissertation to compare temporal and spatial scales allows the measurement of wind gusts from a research aircraft. Then, observations can be obtained from places where traditional weather stations or meteorological masts cannot be deployed. Applying the new method, the observed wind gusts from the marine Arctic matched well with those observed at a meteorological mast in the Baltic Sea, although also differences were observed between these environments. Doppler lidar provides radial wind speed measurements along a laser beam transmitted by the instrument. When data from at least three lines of sight are combined, the three-dimensional wind vector can be derived. However, the measurements from multiple lines of sight take several seconds, and the different beams represent different measurement volumes. For these reasons, the measured wind speed maxima from the Doppler lidar used in this work were higher than the corresponding wind gusts from the nearby meteorological mast. In this dissertation, we developed a new theoretical method that significantly reduced this positive bias. Wind gust measurements are usually prone to measurement errors, called outliers. The use of a spike removal algorithm typically applied in traditional turbulence measurements, resulted in significantly improved Doppler lidar data quality. The method performed even better than the traditional data quality assurance methods based on carrier-to-noise ratio, by removing the unrealistic outliers present in the time series. Based on the above wind gust measurements, it was found that in the lowest part of the atmospheric boundary layer the ratio of the wind gust speed and the mean wind speed, called the gust factor, decreases strongly with measurement height. The higher the aerodynamic roughness of the surface, the greater is the change. Moreover, the static stability of the atmosphere affects the gust factor: the decrease of the gust factor with height is clearly smaller in unstable than in stable conditions. The gust parameterizations used in numerical weather rediction models were originally designed for the reference measurement height of 10 m. A new parameterization was developed that takes into account not only the effects of surface roughness and atmospheric stability but also the height above the surface. Based on meteorological mast and research aircraft measurements, the new parametrization yielded better results than previous methods.
  • Lehtonen, Ilari (Finnish Meteorological Institute, 2017)
    Finnish Meteorological Institute Contributions 133
    The aim of this work was to study the climate change impact on two specific abiotic risks affecting forests in Finland: fires and heavy snow loads. Approximately 1000 forest fires occur annually in Finland, but thanks to effective fire suppression, the average size of fires is only about 0.5 ha. Occasionally, heavy snow loading causes forest damage, which reduces stand quality in boreal forests experiencing cold winters. In Finnish forests, snow damage occurs most commonly in the eastern and northern parts of the country. The basic tools used in this work to evaluate the climate change impact were climate models. In addition, observational weather data and fire statistics were used. In evaluating the forest fire risk, the Canadian Fire Weather Index (FWI) system was used. Snow load amounts were estimated mainly by applying a snow load model developed at the Finnish Meteorological Institute (FMI). The results indicate that forest fire risk will most likely increase in the future due to increasing temperature and enhanced evaporation. However, there is large uncertainty regarding the rate of change, which originates from the differences between climate model responses to the same radiative forcing. Moreover, an increase in forest fire risk will at the same time increase the risk of onflagrations. Crown snow loads were projected to become heavier in northern Finland and in the regions of Kainuu and North Karelia next to the Russian border. In southern and western Finland the risk of snow damage is expected to decrease. The largest decrease in the risk is projected to occur in coastal areas. In the areas expected to experience increased risk of snow damage, conditions favouring oth heavy wet snow loading and rime accretion were predicted to become more common. The results of this work can be utilized when considering climatically-driven risks in forest management.
  • Vazquez, L; Harri, A-M; Genzer, M (Finnish Meteorological Institute, 2017)
    Raportteja – Rapporter – Reports 2017:5
    The “ExoMars Atmospheric Science and Missions” Workshop served as a forum for general discussions on Martian atmospheric science with a focus on the assessment of the results and instrumentation development cycle of the ExoMars 2016 mission. These led to presentations and discussions of the atmospheric investigation plans and strategies for the ESA ExoMars-2020 mission in particular and for forthcoming Mars missions in general. The workshop gave overviews of the ExoMars atmospheric investigations through invited talks by Exomars scientists. The ExoMars atmospheric results and planned investigations were covered by individual scientific presentations. The workshop engaged early career scientists, inclusiveness states and scientific and technological cooperation in the European planetary science community. The Workshop provided a forum for discussion and debate on the outstanding scientific topics of the Martian atmosphere, and on how to integrate and network the scientific teams with providers of instruments and technical systems. Thus the workshop also contributed to international cooperation in the field of Martian atmospheric science and technology.
  • Verronen, Pekka (Finnish Meteorological Institute, 2017)
    Raportteja - Rapporter - Reports 4:2017
    The 13th International Workshop on Greenhouse Gas Measurements from Space (IWGGMS) will be held on 6-8 June, 2017, at the University of Helsinki in Helsinki, Finland. The workshop is organised by the Finnish Meteorological Institute with support from the University of Helsinki. The workshop gathers together more than 160 scientists from the EU, USA, Japan, China, Australia, Canada, and Russia. This report is the official abstract book of the workshop. Background. Success in space-based global measurement of greenhouse gases, such as carbon dioxide and methane, is critical for advancing the understanding of carbon cycle. The recent developments in observations and in interpreting the data are very promising. Space-based greenhouse gas measurement, however, poses a wide array of challenges, many of which are complex and thus demand close international cooperation. The goal of the workshop is to review the state of the art in remote sensing of CO 2 , CH 4 , and other greenhouse gases from space including the current satellite missions, missions to be launched in the near future, emission hot spots on regional and global scales, process studies and interactions of carbon cycle and climate, pre-flight and on-orbit instrument calibration techniques, retrieval algorithms and uncertainty quantification, validation methods and instrumentation, related ground-based, shipboard, and airborne measurements, and flux inversion from space based measurements. The workshop is part of the programme for the centenary of Finland's independence in 2017. The workshop is also one of the activities arranged by the Finnish Meteorological Institute to support Finland's chairmanship of the Arctic Council, 2017 - 2019. The workshop is sponsored by the Finnish Meteorological Institute, the University of Helsinki, the European Space Agency, the City of Helsinki, the Federation of Finnish Learned Societies, and ABB Inc.
  • Laakia, Jaakko (Finnish Meteorological Institute, 2017)
    Finnish Meteorological Institute Contributions 131
    This thesis covers two aspects of utilisation of advanced separation technology together with mass spectrometry: 1. Drift tube ion mobility spectrometry – mass spectrometry (IMS-MS) studies of the behaviour of ions in the gas phase and 2. Comprehensive two dimensional gas chromatography – time-offlight mass spectrometry (GC×GC-TOF-MS) studies for characterization of crude oil samples. In IMS studies, the focus was on the separation of isomeric compounds. For example, [M-H]- ions of 2,4-di-tert-butylphenol (2,4-DtBPh) and 2,6-di-tert-butylphenol (2,6-DtBPh) were separated. It was also observed that shielding of the charge site by the functional groups of a molecule has a large effect on the separation of the isomeric compounds. For example, amines with a shielded charge site were separated from those with a more open charge site, while some of the isomeric amines studied were not separated. Different kinds of adduct ions were observed for some of the analytes. Dioxygen adducts were seen for 2,4-DtBPh [M+O2]-, 2,6-di-tert-butylpyridine (2,6-DtBPyr) [M+O2]+· and 2,6-di-tert-butyl-4-methylpyridine (2,6-DtB-4MPyr) [M+O2]+·. The adduct formation increases the total mass of the analyte ion, and therefore, for example the 2,4-DtBPh [M+O2]- ion could be separated from its isomeric compound 2,6-DtBPh [M-H]-, which did not from the dioxygen adduct ion. In the case of 2,6-DtBPyr and 2,6-DtB-4MPyr, the [M]+ ions formed dioxygen adduct [M+O2]+· ions. The both ions, [M]+ and [M+O2]+·, shared the same drift time which was longer than their [M+H]+ ion species. This work demonstrates that measuring with IMS the mobility of different ion structures of the same molecule, especially dioxygen adducts, results in a better understanding of the role of adduct ions in the IMSseparation process. In GC×GC-TOF-MS studies, the focus was on detailed characterization of crude oil samples. For instance, oils from the Recôncavo Basin were classified to two different groups by using minor oil components. The GC×GC-TOF-MS data showed the correlation between 2D retention time and the number of carbons in a ring for several hydrocarbons as known from the literature. This information was used to achieve more structural information about eight new tetracyclic compounds, some of them similar to nor-steranes, detected during analysis. Some of these new compounds could be used as maturity indicators. This study demonstrated how GC×GC-TOF-MS can be used to separate geochemically interested isomers, identify minor geochemical differences between oils and achieve structural information about unknown biomarkers.