Ilmatieteen laitos

Recent Submissions

  • Gao, Yao (2016)
    Finnish Meteorological Institute Contributions 124
    Interactions between the land surface and climate are complex as a range of physical, chemical and biological processes take place. Changes in the land surface or the climate can affect the water, energy and carbon cycles in the Earth system. This thesis discusses a number of critical issues that concern land-atmospheric interactions in the boreal zone, which is characterised by vast areas of peatlands, extensive boreal forests and a long snow cover period. Regional climate modelling and land surface modelling were used as the main tools for this study, in conjunction with observational data for evaluation. First, to better describe the present-day land cover in the regional climate model, we introduced an up-to-date and high-resolution land cover map to replace the inaccurate and outdated default land cover map for Fennoscandia. Second, in order to provide background information for future forest anagement actions for climate change mitigation, we studied the biogeophysical effects on the regional climate of peatland forestation, which has been the dominant land cover change in Finland over the last century. Moreover, climate variability can influence the land surface. Although drought is uncommon in northern Europe, an extreme drought occurred in the summer of 2006 in Finland, and induced visible drought symptoms in boreal forests. Thus, we assessed a set of drought indicators with drought impact data in boreal forests in Finland to indicate summer drought in boreal forests. Finally, the impacts of summer drought on water use efficiency of boreal Scots pine forests were studied to gain a deeper understanding of carbon and water dynamics in boreal forest ecosystems. In summary, the key findings of this thesis include: 1) the updated land cover map led to a slight decrease in biases of the simulated climate conditions. It is expected that the model performance could be improved by further development in model physics. 2) Peatland forestation in Finland can induce a warming effect in the spring of up to 0.43 K and a slight cooling effect in the growing season of less than 0.1 K due to decreased surface albedo and increased evapotranspiration, respectively. Corresponding to spring warming, the snow clearance day was advanced by up to 5 days over a 15-year mean. 3) The soil moisture index SMI was the most capable of the assessed drought indicators in capturing the spatial extent of observed forest damage induced by the extreme drought in 2006 in Finland. Thus, a land surface model capable of reliable predictions of regional soil moisture is important in future drought predictions in the boreal zone. 4) The inherent water use efficiency (IWUE) showed an increase during drought at the ecosystem level, and IWUE was found to be more appropriate than the ecosystem water use efficiency (EWUE) in indicating the impacts of drought on ecosystem functioning. The combined effects of soil moisture drought and atmospheric drought on stomatal conductance have to be taken into account in land surface models at the global scale when simulating the drought effects on plant functioning.
  • Marnela, Marika (Finnish Meteorological Institute, 2016)
    Finnish Meteorological Institute Contributions 122
    The Arctic Ocean and its exchanges with the Nordic Seas influence the north-European climate. The Fram Strait with its 2600 m sill depth is the only deep passage between the Arctic Ocean and the other oceans. Not just all the deep water exchanges between the Arctic Ocean and the rest of the world's oceans take place through the Fram Strait, but also a significant amount of cold, low-saline surface waters and sea ice exit the Arctic Ocean through the strait. Correspondingly, part of the warm and saline Atlantic water flowing northward enters the Arctic Ocean through the Fram Strait bringing heat into the Arctic Ocean. The oceanic exchanges through the Fram Strait as well as the water mass properties and the changes they undergo in the Fram Strait and its vicinity are studied from three decades of ship-based hydrographic observations collected from 1980-2010. The transports are estimated from geostrophic velocities. The main section, comprised of hydrographic stations, is located zonally at about 79 °N. For a few years of the observed period it is possible to combine the 79 °N section with a more northern section, or with a meridional section at the Greenwich meridian, to form quasi-closed boxes and to apply conservation constraints on them in order to estimate the transports through the Fram strait as well as the recirculation in the strait. In a similar way, zonal hydrographic sections in the Fram Strait and along 75 °N crossing the Greenland Sea are combined to study the exchanges between the Nordic Seas and the Fram Strait. The transport estimates are adjusted with drift estimates based on Argo floats in the Greenland Sea. The mean net volume transports through the Fram Strait are averaged from the various approaches and range from less than 1 Sv to about 3 Sv. The heat loss to the atmosphere from the quasi-closed boxes both north and south of the Fram Strait section is estimated at about 10 TW. The net freshwater transport through the Fram Strait is estimated at 60-70 mSv southward. The insufficiently known northward transport of Arctic Intermediate Water (AIW) originating in the Nordic Seas is estimated using 2002 Oden expedition data. At the time of data collection, excess sulphur hexafluoride (SF6) was available, a tracer that besides a background anthropogenic origin derives from a mixing experiment in the Greenland Sea in 1996. The excess SF6 can be used to distinguish AIW from the upper Polar Deep Water originating in the Arctic Ocean. It is estimated that 0.5 Sv of AIW enters the Arctic Ocean. The deep waters in the Nordic Seas and in the Arctic Ocean have become warmer and in the Greenland Sea also more saline during the three decades studied in this work. The temperature and salinity properties of the deep waters found in the Fram Strait from both Arctic Ocean and Greenland Sea origins have become similar and continue to do so. How these changes will affect the circulation patterns will be seen in the future.
  • Tukiainen, Simo (Finnish Meteorological Institute, 2016)
    Finnish Meteorological Institute Contributions 123
    Measurements of the Earth's atmosphere are crucial for understanding the behavior of the atmosphere and the underlying chemical and dynamical processes. Adequate monitoring of stratospheric ozone and greenhouse gases, for example, requires continuous global observations. Although expensive to build and complicated to operate, satellite instruments provide the best means for the global monitoring. Satellite data are often supplemented by ground-based measurements, which have limited coverage but typically provide more accurate data. Many atmospheric processes are altitude-dependent. Hence, the most useful atmospheric measurements provide information about the vertical distribution of the trace gases. Satellite instruments that observe Earth's limb are especially suitable for measuring atmospheric profiles. Satellite instruments looking down from the orbit, and remote sensing instruments looking up from the ground, generally provide considerably less information about the vertical distribution. Remote sensing measurements are indirect. The instruments observe electromagnetic radiation, but it is ozone, for example, that we are interested in. Interpreting the measured data requires a forward model that contains physical laws governing the measurement. Furthermore, to infer meaningful information from the data, we have to solve the corresponding inverse problem. Atmospheric inverse problems are typically nonlinear and ill-posed, requiring numerical treatment and prior assumptions. In this work, we developed inversion methods for the retrieval of atmospheric profiles. We used measurements by Optical Spectrograph and InfraRed Imager System (OSIRIS) on board the Odin satellite, Global Ozone Monitoring by Occultation of Stars (GOMOS) on board the Envisat satellite, and ground-based Fourier transform spectrometer (FTS) at Sodankylä, Finland. For OSIRIS and GOMOS, we developed an onion peeling inversion method and retrieved ozone, aerosol, and neutral air profiles. From the OSIRIS data, we also retrieved NO2 profiles. For the FTS data, we developed a dimension reduction inversion method and used Markov chain Monte Carlo (MCMC) statistical estimation to retrieve methane profiles. Main contributions of this work are the retrieved OSIRIS and GOMOS satellite data sets, and the novel retrieval method applied to the FTS data. Long satellite data records are useful for trends studies and for distinguishing between anthropogenic effects and natural variations. Before this work, GOMOS daytime ozone profiles were missing from scientific studies because the operational GOMOS daytime occultation product contains large biases. The GOMOS bright limb ozone product vastly improves the stratospheric part of the GOMOS daytime ozone. On the other hand, the dimension reduction method is a promising new technique for the retrieval of atmospheric profiles, especially when the measurement contains little information about the vertical distribution of gases.
  • Mäkelä, Antti; Laurila, Terhi; Haapalainen, Jussi (Ilmatieteen laitos, 2016)
    Raportteja - rapporter - Reports 2016:5
    Ilmatieteen laitos on koonnut ja julkaissut salamanlaskijoiden havainnot vuosilta 1960–1997. Vuodesta 1998 lähtien kaikki järjestelmälliset maasalamahavainnot perustuvat salamanpaikantimeen, jonka nykyinen malli aloitti toimintansa elokuussa 1997. Se käsitti 2015 kahdeksan anturia, pohjoisin Lokassa. Vuodesta 2002 mukana ovat olleet lisäksi Norjan ja Ruotsin anturit, joiden ansiosta koko Lappi on katettu ja suorituskyky on parantunut myös muualla Suomessa, sekä yksi anturi Virossa (mukaan vuonna 2005) ja kolme anturia Liettuassa (mukaan 2014). Laitteisto paikantaa maasalamoista erikseen jokaisen osaiskun ja ryhmittelee ne kokonaisiksi salamoiksi. Paikannettu salama voi sisältää 1-15 iskua; keskiarvo Suomessa on vajaa kaksi iskua/salama. Tilastoinnin pohjana käytetään salama- eikä iskumääriä, koska salama on ilmastollisesti edustavampi suure. Kesän 2015 aikana paikannettiin Suomen alueella ennätyksellisen vähän maasalamoita, noin 30 000, joka on vain viidennes keskimääräisestä (139 000). Suomen kesää pitkään hallinnut viileä säätyyppi ei suosinut rajuja ukkosia, ja elokuun lämmin ilmamassa estyi tuottamasta ukkospilviä korkeapainevoittoisen sään vuoksi. Kuukausista ainoastaan syyskuu ylsi hieman yli keskimääräisen.
  • Verronen, P.T. (editor) (Finnish Meteorological Institute, 16-0)
    Raportteja - Rapporter - Reports 2016:4
    Tervetuloa kuudenteen kansainväliseen HEPPA-SOLARIS-kokoukseen, jonka Ilmatieteen laitos järjestää 13.-17. kesäkuuta 2016 Helsingissä. Kokous jatkaa vuodesta 2008 järjestettyjen kokousten sarjaa, jonka aiheena on auringon säteilyn ja korkeaenergisen hiukkaspresipitaation vaikutukset ilmakehään ja ilmastoon. Kokoukseen osallistuu kansainvälinen joukko tutkijoita, jotka esittelevät sekä havaintoihin että tietokonemallinnukseen perustuvia tuloksiaan. Tämä raportti sisältää em. esitysten tiivistelmät. Kokouksen aihepiiri kattaa a) auringon säteilyn ja hiukkaspresipitaation vaihtelut ja näihin liittyvät ilmiöt, b) kemiallisten ja dynaamisten ilmakehävaikutusten mekanismit c) vaikutukset avaruudessa ja ilmakehässä sekä kytkennät ilmastoon, d) tutkimusta tukevat havainnot, tietokonemallit ja menetelmät nyt ja tulevaisuudessa. IAMAS/IUGG, VarSITI/SCOSTEP ja SPARC tukevat kokousta tieteellisesti ja taloudellisesti.
  • Soares, Joana (Finnish Meteorological Institute, 2016)
    Finnish Meteorological Institute Contributions 121
    Atmospheric aerosols are subject to extensive research, due to their effect on air quality, human health and ecosystems, and hold a pivotal role in the Earth’s climate. The first focus of this study is to improve the modelling of aerosol emissions and its dispersion in the atmosphere, in different spatial and temporal scales, and secondly, to integrate the dispersion modelling with population activity data to estimate exposure metrics. The mathematical models used in this study are fully or partially developed by the Finnish Meteorological Institute: a regional-to-global scale chemical transport model SILAM, a local-scale point/line-source dispersion model, UDM/CAR-FMI, and a human exposure and intake fraction assessment model, EXPAND. One of the outcomes of this work was the refinement of the emission modelling for the mesoscale dispersion model. A new parameterisation for bubble-mediated sea salt flux has been developed, taking in to account the effects of wind speed and seawater salinity and temperature. The parameterization is valid for low-to-moderate wind speed, seawater salinity ranging between 0 and 33 ‰, seawater temperature ranging between -2 and 25 °C, and can be applicable to particles with dry diameters raging between 0.01 and 10 μm. The near-real time fire estimation system, IS4FIRES, based on Fire Radiative Power (FRP) measured by the remote sensing instrument MODIS, was refined to reduce the overestimation of particulate matter (PM) emissions by including more vegetation types, improving the diurnal variation, removing misattributed fires from the FRP data, and recalibrating the emission factors. Applying dynamic emission modelling brought more insight to the spatial distribution of these emissions, their contribution to the atmospheric budget, and possible impact on air quality and climate. The modelling shows that sea salt can be transported far over land and contribute up to 6 μg m-3 to PM10 (at annual level). It also indicates that the Mediterranean Sea has sharp gradients of concentration, becoming an interesting area to analyse regarding the feedbacks to the regional climate. According to the predictions, upward scattering by SSA, at TOA, can be up to 0.5 W m-2, and there will be an overall cooling in the future for the North of Europe and warming for the South, due to SSA. The simulations for wildland fires show how the system improves after calibration and the importance vegetation type for the intensity of the emissions. By including misattributed fires, there will be up to 80% overestimation in aerosol optical depth, close to the misattributed sources. The emissions for Helsinki Metropolitan Area (HMA) were revised to bring up-to-date the emissions for traffic and energy sectors, for urban-scale applications. The EXPAND model was revised to combine concentrations and activity data in order to compute parameters such as population exposure or intake fraction. EXPAND includes improvements of the associated urban emission and dispersion modelling system, time use of population, and infiltration coefficients from outdoor to indoor air. This refinement showed that PM2.5 in HMA is mainly originated from long-range transport, with the largest local contributors being vehicular and shipping (at harbours and its vicinity) emissions. At annual level, the population is mostly exposed to PM2.5 indoors (home and work), but the population is acutely exposed while commuting.
  • Aurela, Minna (2016)
    Finnish Meteorological Institute Contributions 120
    Atmospheric aerosols have a significant effect on people and the environment. They cause adverse health effects especially for cardiorespiratory patients. Atmospheric aerosols also affect the Earth’s climate directly by scattering and absorbing solar radiation and indirectly by modifying amounts and properties of clouds. Reliable characterisation and quantification of airborne particles and their sources are essential for developing control strategies for atmospheric pollution and decreasing the uncertainties of estimating particles effects on climate change. Aerosols can be divided into fine and coarse particles based on their size. This thesis concentrated on fine particles, which are either directly emitted into the atmosphere (primary particles) or formed in the atmosphere through gas-to-particle conversion (secondary particles). The main sources of atmospheric fine particles are natural and anthropogenic combustion, industry and secondary aerosol formation (biogenic and anthropogenic). The overall objective of this thesis was to investigate the chemical composition of fine particles with different temporal and seasonal time-scales. For this purpose, a variety of different sampling techniques, off-line analytical methods and on-line instruments were used to characterise the main chemical species of fine particles in simultaneous and independent campaigns at several sites mainly in southern Finland but also in South Africa. More specific objectives were to investigate the dominant sources of particulate organic matter in the Helsinki area and chemically characterise the fine particles originating from biomass burning. Determining the effect of air mass origin on the chemical composition and concentration of fine particles was also one of the specific aims. In this thesis, it was found that the chemical composition of fine particles had strong spatial and temporal variation, although on average the mass concentrations of fine particles were quite similar between different sites. The main components in fine particulate matter in southern Finland was particulate organic matter (POM), followed by sulphate, whereas sulphate had the highest contribution to particulate mass in South Africa. Source apportionment analysis of POM revealed clear primary sources from traffic and from biomass burning. However, the secondary organic aerosol had the largest contribution of POM, even though the campaigns were conducted in specific environments such as residential areas where biomass combustion is commonly used or traffic environments. Occasionally, the contribution of biomass burning organic aerosol increased substantially as ambient air temperature decreased. Additionally, simultaneous measurements pointed out a high contribution of common regional or longrange transported sources over large areas of southern Finland. Similarly, the air mass passing over either clean or polluted areas showed a significant effect on the mass concentrations in Finland and South Africa.
  • Venäläinen, Ari; Lehtonen, Ilari; Mäkelä, Antti (Ilmatieteen laitos, 2016)
    Raportteja - rapporter - Reports 2016:3
  • Laakso, Anton (Finnish Meteorological Institute, 16-0)
    Finnish Meteorological Institute Contributions 119
    Atmospheric aerosols have been shown to exert a cooling effect on climate by scattering incoming solar radiation back to space or increasing cloud albedo by increasing the cloud droplet number concentration in the clouds. If greenhouse gas emissions cannot be reduced to slow down climate warming, it has been postulated that climate could be artificially cooled by increasing atmospheric aerosol concentrations. These methods are called solar radiation management or geoengineering. This work evaluated two potential solar radiation management techniques; 1) where marine aerosol concentrations would be elevated to enhance marine cloud albedo and 2) a technique where stratospheric sulphur concentration would be increased. The key objectives of this thesis were to: 1) Investigate the potential of aerosols to cool the climate at the global scale, 2) Evaluate the role of the simulation of the aerosol microphysics in the global climate models and 3) Identify the possible limits in the effectiveness of the Solar Radiation Management techniques as well as the risks related to these techniques. Climate is already being affected by our current aerosols emissions. This work also examined how the geographical change in aerosol emissions has affected the climate and evaluated how the climate would change due to aerosols if all electrical energy were to be generated by nuclear power is instead of by coal combustion. The global aerosol-climate model ECHAM-HAMMOZ was used to study radiation and the climatic effects of aerosols. The model simulates the formation, growth, transportation and deposition of aerosols and their interactions with clouds. In addition, the effects on the climate, assessed as temperature changes, were studied using a mixed layer ocean model coupled to the atmospheric model ECHAM and Max Planck Institute's Earth System Model (MPI-ESM). The results revealed that the geoengineering techniques which were studied in this work, have the potential to significantly cool climate and thus slow down global warming. However, the cooling effect has limitations. Stratospheric sulphur injections would lead to relatively less cooling, should the amount of injected sulphur need to be increased. Thus for example, a large volcanic eruption would also lead to a clearly smaller and shorter period cooling if the volcano were to erupt during the stratospheric sulphur injections than if the eruption took place in an unperturbed atmosphere. This work also studied if ship or air traffic were to be used for geoengineering by increasing sulphur concentration in fuel. This would lead to a significant cooling effect but would require changes in current legislation. Even if this were to occur, the cooling effect would be concentrated around the vicinity of routes of the traffic and would thus lead to a regionally uneven cooling effect. Furthermore, the cooling effect would be clearly smaller compared to injection strategies which were intended to maximize the cooling effect of aerosols. The global mean cooling effect attributable to aerosols would be rather small due to the geographical change in tropospheric aerosol emissions or change in energy production studied here when compared to the warming due to the increased greenhouse gas emissions. This work shows the necessity of including aerosol microphysics into climate modelling since most of the conclusions in this work could not be obtained without aerosol microphysics or taking into account the interactions between clouds and aerosols. Thus, micrometer scale physical phenomena would influence the climatic impact on a global scale. Simulating aerosol microphysics led also to many unpredictable results.
  • Haavisto, Riina; Pilli-Sihvola, Karoliina; Harjanne, Atte; Perrels, Adriaan (Ilmatieteen laitos, 2016)
    Raportteja - rapporter - Reports 2016:1
    Abstract Improved weather and marine services (WMS) can have a role to play in the safe and secure development of the Arctic region through either a demand-pull (enhanced by growth in activity) or a supply-push (enhances growth in activity) process. To analyse the nature of the process and the future use and benefits of WMS, a better understanding of possible future developments in the Eurasian Arctic is needed. This report presents six socio-economic scenarios for the Eurasian Arctic by 2040, and a brief synopsis of the implications of each scenario for WMS. The scenarios focus on the development of shipping, resource extraction and tourism industries. The scenario futures, called Wild West, Silicon Valley, Exploited Colony, Shangri La, Conflict Zone and Antarctic, describe the scale and scope of activities in the Eurasian Arctic by 2040. The scenarios have three dimensions: open – closed, public - private and dirty – clean, which describe the political, economic, social, technological and environmental aspects of different futures. The scenarios are based on a literature review, pre-survey, expert workshop and restructuring and analysis of this material. The methodology used for scenario construction is described in detail and may be used widely by other scenario developers. Our analysis shows that plenty of potential pressures for major changes in the Eurasian Arctic exist. Environmental changes, political shifts and technological development can all push forward drastic new developments in the region. Then again, it is possible that despite all the hype and interest, the Eurasian Arctic remains backwater areas in the global economy. This emphasizes the need for any decision-maker to be able to respond to very different futures. Therefore, robust decision making, a good eye for weak signals and tipping points, and the ability to prepare for risks and seize opportunities as they emerge is required in the Eurasian Arctic. The development of WMS is important in ensuring the safe and secure development of the Eurasian Arctic, unless the development follows the path of “Antarctica” with tourism and research as main activities in the marine regions. Tiivistelmä Paremmat sää- ja meripalvelut voivat vaikuttaa Arktisen alueen turvalliseen kehitykseen joko kysyntävetoisesti (toiminnan kasvu lisää aiempaa parempien sää- ja meripalvelujen kysyntää) tai tarjontavetoisesti (parantuneet sää- ja meripapalvelut lisäävät toimintaa). Tulevaisuuden sää- ja meripalveluiden kysynnän taustalla olevan prosessin ymmärtäminen ja palveluiden tuottamien hyötyjen analysointi tarvitsevat tuekseen ymmärryksen siitä, millainen Euraasian arktinen alue tulevaisuudessa voi olla. Tämä raportti esittelee kuusi sosioekonomista skenaariota Euraasian arktiselle alueelle vuodelle 2040 ja kuvailee lyhyesti, kuinka kukin skenaario vaikuttaa sää- ja meripalveluihin. Kuudelle eri tulevaisuudelle annetut nimet Wild West, Silicon Valley, Exploited Colony, Shangri La, Conflict Zone ja Antarctic, kuvaavat Euraasian arktisella alueella olevan toiminnan mittasuhteita ja laajuutta vuodelle 2040. Skenaarioilla on kolme ulottuvuutta: avoin – suljettu, julkinen – yksityinen ja likainen – puhdas. Nämä ulottuvuudet kuvaavat skenaarioiden poliittisia, taloudellisia, sosiaalisia, teknologisia ja ympäristöllisiä lähtökohtia. Skenaariot perustuvat kirjallisuuskatsauksen, ennakkokyselyn ja asiantuntijatyöpajan tuottaman materiaalin perusteelliseen analysointiin. Skenaarioiden tuottamiseen käytetty menetelmä on kuvattu raportissa ja sitä voivat käyttää muut skenaarioiden kehittäjät. Analyysimme osoittaa, että Euraasian arktinen alue kohtaa monia mahdollisia muutospaineita. Ympäristömuutokset, poliittinen tahtotila ja teknologian kehittyminen voivat kaikki viedä eteenpäin jopa dramaattisia uusia kehityssuuntia. Toisaalta, huolimatta suuresta innostuksesta ja kiinnostuksesta minkä arktinen alue on saanut osakseen, Euraasian arktinen alue voi mahdollisesti pysyä syrjäseutuna globaalissa maailmantaloudessa. Tämä korostaa jokaisen päätöksentekijän tarvetta pystyä reagoimaan hyvin erilaisten tulevaisuuksien toteutumiseen. Siksi vakaa ja kestävä päätöksenteko, heikkojen signaalien ja kriittisten pisteiden havaitseminen sekä kyky valmistautua riskeihin ja tarttua tilaisuuksiin niiden ilmaantuessa ovat Euraasian arktisella alueella tarpeen. Sää- ja meripalveluiden kehittäminen on tärkeässä osassa mahdollistamassa alueen turvallisen kehityksen, paitsi silloin jos kehitys seuraa ”Antarctic” kehityspolkua, jossa matkailu ja tutkimus ovat alueen keskeisimmät toimintamuodot.
  • Makkonen, Ulla; Saarnio, Karri; Ruoho-Airola, Tuija; Hakola, Hannele (Ilmatieteen laitos, 2016)
    Raportteja - Rapporter - Reports 2016:2
    Tiivistelmä Itämeren pahimpana ongelmana pidetään typpi- ja fosforikuormituksen aiheuttamaa rehevöitymistä. Typpeä ja fosforia joutuu Itämereen paitsi valumana rantavaltioista myös merkittävissä määrin ilman kautta. Ilmaperäisen typpilaskeuman määrää ja sen kehitystä on selvitetty mittauksin ja mallinnuksen avulla 1980-luvulta lähtien, mutta ilmaperäistä fosforikuormaa Itämereen on mitattu vain sateen mukana laskeutuvan märkälaskeuman osalta muutamilla asemilla. Hiukkasiin sitoutuneesta kuivalaskeumasta ei mittaustietoa ole julkaistu lainkaan, eikä Itämeren ympärysvaltioilla ole käytettävissään menetelmää ilmaperäisen fosforikuorman hiukkasosuuden seuraamiseksi. Tässä työssä kehitettiin ja testattiin menetelmät ilmakehästä sadeveden mukana tulevan sekä ilmakehän hiukkasiin sitoutuneen fosfaatin sekä kokonaisfosforin määrittämiseksi. Menetelmäkehitys sisälsi näytteenkeruumenetelmät, näytteen esikäsittelymenetelmät sekä kemialliset analyysimenetelmät. Menetelmiä testattiin Utön saarella Saaristomeren ulkolaidalla vuosien 2013–2015 aikana. Utön saarella toimii Ilmatieteen laitoksen mittausasema, jonka mittaustulokset edustavat ilmanlaadun tausta-arvoja pohjoisella Itämerellä. Testattuina fosforin ja fosfaatin kuiva- ja märkälaskeuman näytteenkeruumenetelminä toimivat olemassa olevat ja laajasti käyttöönotetut EMEP-protokolliin perustuvat menetelmät. Näytteiden kokonaisfosforipitoisuuden määritysmenetelmään sovellettiin olemassa olevaa ISO-standardiin perustuvaa spektrometristä menetelmää. Vesiliukoisen fosfaatin pitoisuuden määrittämiseen hyödynnettiin käytössä olevaa ISO-standardiin perustuvaa ionikromatografista menetelmää, jota laajennettiin sisältämään fosfaatin määritys muiden epäorgaanisten ionien kanssa samassa analyysissä. Havaittiin, että sekä märkä- että kuivalaskeumanäytteiden sisältämät kokonaisfosfori- ja fosfaattipitoisuudet olivat erittäin alhaisia, usein pitoisuudet olivat lähellä analyysimenetelmien määritysrajoja tai niiden alle. Kuitenkin mittausjakson ajalta saatiin riittävä määrä määritystuloksia, joiden avulla voidaan laskea aiempaa luotettavampi arvio vuotuisesta ilmaperäisestä fosforikuormituksesta Itämereen. Työssä tutkittiin Utön saaren mittausasemalla suoritetun intensiivikampanjan aikana mahdollisuutta määrittää hiukkasissa olevan fosfaatin pitoisuutta jatkuvatoimisella ionikromatografilla. Menetelmän herkkyys osoittautui kuitenkin riittämättömäksi ilmakehän hiukkasten fosfaattipitoisuuden määrittämiseen. Käytetyt menetelmät on esitelty tässä raportissa siten, että menetelmät voidaan ottaa käyttöön muillakin mittausasemilla ja laboratorioissa sadeveden ja ilmakehän hiukkasten sisältämien fosfaatin ja kokonaisfosforin pitoisuuksien määrittämiseksi, ja siten ilmaperäisen fosforin kuormitusta voidaan arvioida luotettavammin ja laajemmin Itämeren alueella. Abstract Eutrophication caused by nitrogen and phosphorus load is generally thought as the most severe problem of the Baltic Sea. Nitrogen and phosphorus end up in the Baltic Sea not only by run-off from the coastal countries of the Baltic Sea but to an important extent also from the atmosphere. The amount of atmospheric nitrogen load and its development have been determined using measurements and models since the 1980’s. The atmospheric phosphorus load to the Baltic Sea has been measured earlier only from the wet deposition from the collected rain water samples from a few sites around the Baltic Sea; no published data exists about the particle bound dry deposition of phosphorus. The coastal countries of the Baltic Sea haven’t got any method in use to measure the particle bound phosphorus deposition. In this work, methods for determining the concentrations of phosphate and total phosphorus in atmospheric precipitation and particulate matter were developed and tested. The method development included the sampling, sample pre-treatment, and chemical analysis techniques. The methods were tested onsite on the Utö Island in the outskirts of the Archipelago Sea during the years 2013–2015. The monitoring station on the Utö Island is operated by the Finnish Meteorological Institute. The measurements on the station represent the background air quality of the northern Baltic Sea area. The existing and widely used sampling methods based on the EMEP protocols were tested for the sampling of dry and wet deposition of phosphorus and phosphate. A spectrometric method based on an ISO standard was applied for determination of the total phosphorus concentration of the samples. For the determination of dissolved phosphate, an ion chromatographic method based on an ISO standard was extended to include the analysis of phosphate with the main inorganic ions. It was discovered that the concentrations of total phosphorus and dissolved phosphate in the dry and wet deposition samples were very low; the concentrations were often close to the determination limits of the used analytical methods or even below those. Nevertheless, a sufficiency of samples were determined to be able to estimate the yearly atmospheric phosphorus load to the Baltic Sea more reliably than earlier. In addition, feasibility of measuring the concentration of particle-bound phosphate using a semi-continuous ion chromatograph was tested in the Utö Island during an intensive campaign. However, the sensitivity of the analyser was not sufficient to measure the low atmospheric concentrations of phosphate. The used methods are presented in this report so that they can be taken into use in other sampling sites and laboratories to determine the concentrations of phosphate and total phosphorus in the precipitation and in the atmospheric particulate matter. Thus, more reliable estimates of the atmospheric phosphorus load to the Baltic Sea could be calculated more widely.
  • Savunen, Tarja; Kivi, Rigel; Poikonen, Antti; Kangas, Markku; Säntti, Kristiina; Hyvönen, Reijo; Mammarella, Ivan; Gregow, Erik; Tammelin, Bengt (Ilmatieteen laitos, 2015)
    Raportteja - Rapporter - Reports 2014:9
  • Mäkelä, Antti; Laurila, Terhi (Ilmatieteen laitos, 2015)
    Raportteja - Rapporter - Reports 2015:1
  • Sukuvaara, Timo (Ilmatieteen laitos, 2015)
    Finnish Meteorological Institute Contributions no. 113
  • Venäläinen, Ari; Saku, Seppo; Kilpeläinen, Tiina; Jylhä, Kirsti; Tuomenvirta, Heikki; Vajda, Andrea; Räisänen, Jouni; Ruosteenoja, Kimmo (2015)
    Raportteja - Rapporter - Reports