1,056 research outputs found
Ice investigations using Landsat-2 imagery
There are no author-identified significant results in this report
On the possibilities of determining the basin characteristics by means of satellite images
There are no author-identified significant results in this report
Soil carbon modelling as a tool for carbon balance studies in forestry
Soils represent a remarkable stock of carbon, and forest soils are estimated to hold half of the global stock of soil carbon. Topical concern about the effects of climate change and forest management on soil carbon as well as practical reporting requirements set by climate conventions have created a need to assess soil carbon stock changes reliably and transparently. The large spatial variability of soil carbon commensurate with relatively slow changes in stocks hinders the assessment of soil carbon stocks and their changes by direct measurements. Models therefore widely serve to estimate carbon stocks and stock changes in soils.
This dissertation aimed to develop the soil carbon model YASSO for upland forest soils. The model was aimed to take into account the most important processes controlling the decomposition in soils, yet remain simple enough to ensure its practical applicability in different applications. The model structure and assumptions were presented and the model parameters were defined with empirical measurements. The model was evaluated by studying the sensitivities of the model results to parameter values, by estimating the precision of the results with an uncertainty analysis, and by assessing the accuracy of the model by comparing the predictions against measured data and to the results of an alternative model.
The model was applied to study the effects of intensified biomass extraction on the forest carbon balance and to estimate the effects of soil carbon deficit on net greenhouse gas emissions of energy use of forest residues. The model was also applied in an inventory based method to assess the national scale forest carbon balance for Finland’s forests from 1922 to 2004.
YASSO managed to describe sufficiently the effects of both the variable litter and climatic conditions on decomposition. When combined with the stand models or other systems providing litter information, the dynamic approach of the model proved to be powerful for estimating changes in soil carbon stocks on different scales. The climate dependency of the model, the effects of nitrogen on decomposition and forest growth as well as the effects of soil texture on soil carbon stock dynamics are areas for development when considering the applicability of the model to different research questions, different land use types and wider geographic regions.
Intensified biomass extraction affects soil carbon stocks, and these changes in stocks should be taken into account when considering the net effects of forest residue utilisation as energy. On a national scale, soil carbon stocks play an important role in forest carbon balances.Metsien maaperän hiilivarastolla on merkittävä rooli metsien hiilitaseessa. Hakkuutähteiden keruu hakkuiden jälkeen vähentää puustosta maaperään siirtyvää hiilen määrää ja tämä hiilivarastomuutos on merkittävä verrattuna muihin hakkuutähteiden energiakäytön aiheuttamiin kasvihuonekaasupäästöihin.
Metsien maaperä on merkittävä hiilen varasto. Ilmastonmuutos ja erilaiset metsänkäsittelyt vaikuttavat paitsi puuston biomassan myös maaperän hiilivarastoon. Näitä vaikutuksia ei kuitenkaan vielä täysin tunneta. Kansainvälinen ilmastosopimus kuitenkin velvoittaa sopijamaat raportoimaan myös maaperän hiilivarastossa tapahtuvat muutokset. Maaperän hiilivaraston muutosten arviointi mittaamalla on hyvin vaikeaa ja työlästä, koska varaston spatiaalinen vaihtelu on suurta verrattuna ajallisiin muutoksiin. Tämän vuoksi hiilivaraston ja sen muutosten arvioinnissa käytetään usein malleja.
Tässä väitöskirjassa kehitettiin ja testattiin kivennäismaiden metsien orgaanisen aineen hajoamista ja maaperän hiilivaraston dynamiikkaa kuvaava YASSO-malli. Mallilla pyrittiin kuvaamaan tärkeimmät hiilivaraston dynamiikkaan vaikuttavat tekijät, mutta silti pitämään malli niin yksinkertaisena, että sen toimintaperiaatteiden ymmärtäminen ja käyttö sovelluksissa olisi helppoa. Mallin toimintaa arvioitiin tarkastelemalla mallitulosten herkkyyttä mallin parametriarvojen muutoksille, tutkimalla mallitulosten tarkkuutta epävarmuusanalyysin avulla ja vertaamalla mallituloksia mitattuihin havaintoihin ja toisen maamallin antamiin tuloksiin. Epävarmuus- ja herkkyysanalyysien mukaan YASSO-mallin hiilivarastoarviot ovat epävarmoja. Hiilivarastomuutosten arviot sen sijaan ovat verrattain tarkkoja. Testit mitattuja aineistoja vastaan vastaan osoittivat, että malli onnistuu kohtalaisesti kuvaamaan erilaisten karikkeiden hajoamisen erilaisissa ilmasto-olosuhteissa ja maaperän kokonaishiilivaraston erilaisissa suomalaisissa metsiköissä.
Mallilla tutkittiin hakkuutähteiden talteenoton ja energiakäytön vaikutusta maaperän hiilivarastoon ja maaperän roolia Suomen metsien hiilitaseessa. Mallin dynaaminen lähestymistapa osoittautui tehokkaaksi sovelluksissa, joissa se yhdistettiin metsikkömalliin tai inventointitietoihin ja biomassa- ja karikemalleihin
Valuation of athlete endorsers – a framework for the valuation professional golfers
Sports sponsorship is a field of marketing that has experienced steady growth since the 1980s. It has been used as a means for building brand awareness and differentiating from competitive brands. Even with steady growth, the field has experienced turmoil and debate, since the results it generates are not always calculable due to the multidimensional effects sponsorship may have. As a result, sponsorship lacks certain instruments for measuring the success of it as well as analyzing the direct value it may bring to a company. This being said, the purpose of this study is to develop a framework for the valuation of professional golfers based on quantitative big data.
The research was conducted by gathering data on the athletes selected into the sample group from various different sources. Media coverage was chosen as the primary data for analysis, since based on the literature review, it was seen to be an accurate measure of sponsorship success. The sample group was chosen to consist of the top 10 golfers of the world, since there was the most sufficient data about them available. The analysis of the data was divided into two parts, the first part consisted of analyzing how the success of a player affected the amount of media generated about him. In the second part of analysis, the value of the athletes’ current sponsorship agreements was taken into account in order to arrive on how well the athletes had met their sponsors expectations on value. Finally, the mathematical equations used for analyzing were derived, in order to develop a final equation for the valuation of any athlete endorser of a certain sample group, given that the following metrics were available: tournament winnings, sponsorship income and media coverage.
With these findings it was suggested that more research should be conducted in the field of athlete valuation, since the results implied certain athletes were significantly under or over appreciated compared to the sample group. It was also suggested that more research was to be conducted on the accuracy of media coverage as a metric for analyzing sponsorship success
Säävaihtelun ja ääri-ilmiöiden aiheuttamien riskien hallinta haavoittuvuuden vähentämiseksi ja puskurointi- ja palautumiskyvyn parantamiseksi
Loppuraportti, Ilmapuskuri201
Greenhouse Impact Due to the Use of Combustible Fuels: Life Cycle Viewpoint and Relative Radiative Forcing Commitment
Extensive information on the greenhouse impacts of various human actions is important in developing effective climate change mitigation strategies. The greenhouse impacts of combustible fuels consist not only of combustion emissions but also of emissions from the fuel production chain and possible effects on the ecosystem carbon storages. It is important to be able to assess the combined, total effect of these different emissions and to express the results in a comprehensive way. In this study, a new concept called relative radiative forcing commitment (RRFC) is presented and applied to depict the greenhouse impact of some combustible fuels currently used in Finland. RRFC is a ratio that accounts for the energy absorbed in the Earth system due to changes in greenhouse gas concentrations (production and combustion of fuel) compared to the energy released in the combustion of fuel. RRFC can also be expressed as a function of time in order to give a dynamic cumulative picture on the caused effect. Varying time horizons can be studied separately, as is the case when studying the effects of different climate policies on varying time scales. The RRFC for coal for 100 years is about 170, which means that in 100 years 170 times more energy is absorbed in the atmosphere due to the emissions of coal combustion activity than is released in combustion itself. RRFC values of the other studied fuel production chains varied from about 30 (forest residues fuel) to 190 (peat fuel) for the 100-year study period. The length of the studied time horizon had an impact on the RRFC values and, to some extent, on the relative positions of various fuels
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