The increasing levels of the greenhouse gas carbon dioxide (CO2) in the Earths atmosphere, caused by human release of CO2, has made it desirable to understand the factors determining the CO2-variation because of CO2’s warming effect on the Earths temperature which will change the premises of all life on earth. The purpose of this investigation is to understand the effects of the largest factors of influence on the CO2-concentration - like sea, vegetation and anthropogenic outlets - in the Baltic Sea region, and possible surprises from the results. To be able to do this only from CO2-measurements some assumptions have to be done as starting point. Such are that, besides from the yearly trend of the CO2-concentration and the variation of oceanic influence, monthly variation only is caused by vegetation and that the yearly offset in CO2-levels only is affected by anthropogenic outlets. These factors are together called the local season and will be used for evaluation of the CO2-values for each site. This analysis is done for eight sites surrounding the Baltic Sea region and is compared with results from the site of Östergarnsholm, an island in the Baltic Sea east of Gotland. The results show that stations with high vegetational influence has high amplitudes for the local season compared to sites more influenced by sea. This also makes the amplitude to be connected with latitude since sites with longer growing season is surrounded by higher density of vegetation. The minimum for the local season is also dependent on the growing season, since it occurs when the vegetational consumption is largest. Peaks in the local season can be seen in connection with the maximum decay of the natural vegetation in the early winter months, and with the planting and harvest season for agricultural land. Considering the effect from anthropogenic influence a clear connection in the offset of the local season can be seen, with higher offsets for sites of higher anthropogenic influence and vice versa. Anthropogenic influence also seems to give raised values in summer for the local season, indicating that the variation of the local season cannot be simply connected to only vegetational influence. For variability, higher values in the summer months are seen for the anthropogenic sites, while in winter the variability is more similar for all sites. This might be connected with a higher degree of local influence during summers, which for anthropogenic stations leads to high variability due to inhomogenous surroundings. For Östergarnsholm we get higher amplitude for the local season than expected, this is partly due to unrepresentatively high amplitudes for the seasons used, but also probably to some degree of underestimation of the vegetational influence. Due to correction of the offset it was not possible to draw any conclusions from this factor, but rather give suggestions of what the correction should be. When analysing the local season for different source areas by WD-classification we see the surprising property that the sector that should be most influenced by land, due to higher values in summer, has a lower amplitude than the sector most influenced by sea. Since it was suggested that anthropogenic influence gives raised values in summer this was suggested as an explanation.

During the Arctic summer when the anthropogenic influence is limited, the natural marine source of sulfur in the form of gas-phase dimethyl sulfide viz. DMS(g), is of great importance for cloud formation. The harsh environment of the Arctic makes it difficult to perform in situ measurements of DMS(g) and hence regional model simulations can serve as a complement to increase our understanding of DMS related processes in the Arctic. In this thesis a regional scale meteorological forecast model, extended with DMS(g) calculations, is used to provide a consistent three-dimensional time evolving picture of DMS(g) over the pack-ice region. The analysis focus on meteorological aspects on the horizontal and vertical distribution of DMS(g). Our results show that the amount of DMS(g) over an oceanic source region alone does not determine concentration found over the pack-ice, the prevailing wind also exerts a large influence on the horizontal DMS(g) distribution. The modeled DMS(g) concentrations are advected in plumes in over the pack-ice, which, in combination with the photo-chemical decay, explain the large observed temporal variability of DMS(g) over the pack-ice. The modeled vertical structure show episodes with DMS(g) maxima well above the local boundary layer. Also shown is that DMS(g) maxima can be formed adjacent to frontal zones. In the presence of turbulence DMS(g) can be mixed downwards into the local boundary layer and aid growth to local particles and hence contribute to cloud formation in the boundary layer. / At the time of the doctoral defense the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Manuscript. Paper 4: Manuscript.

Syftet med detta examensarbete är att genomföra och utvärdera en pedagogisk idé. Idén består av att genomföra aktiviteter som på olika sätt riktar de inblandades uppmärksamhet mot väderfenomen och undersöka om detta bidrar till någon form av lärande och utveckling för de inblandade i en pedagogisk verksamhet. Studier påvisar att pedagoger inom förskolan ofta upplever sig ha bristande kunskaper inom det naturveteskapliga området (Andersson 2011). Pedagogerna i min undersökning kunde inte, i inledningsskedet av min studie, nämna något område inom naturvetenskapen som de själva var intresserade av. De kunde heller inte komma på något naturvetenskapligt fenomen som barnen kunde utforska på förskolegården. Resultatet visar att den pedagogiska idén påverkade tänkandet hos de inblandade och gav näring åt det naturvetenskapliga utforskandet. Intervjusamtalen i samband med min studie vidgade pedagogernas tänkande kring uteverksamhetens kvalité och naturvetenskapliga innehåll. Detta resulterade bl. a i att pedagogerna beslutade att på ett strukturerat sätt börja erbjuda barnen planerad pedagogisk verksamhet ute på förskolegården.

The effect that the Polar stratospheric clouds (PSCs) have on the destruction of ozone in the polar vortex is well known. The study of these clouds is therefore highly relevant and important. A tool that can be used to gather parameters needed to describe the PSC is a lidar (Light Detection and Ranging). The Swedish Institute of Space Physics (IRF) uses such a lidar to observe PSCs above Kiruna in northern Sweden. The lidar works by emitting polarised light and then collecting the scattered light. Knowing the time between when the light was emitted and the backscattered light was collected one can then determine at which altitude the scattering happened. The time and the backscattered light can then be used to derive the useful parameters needed to create a climatology of the PSCs. When creating a climatology, the different types of PSCs (type Ia, Ib and II) have to be classified. Each of the different types is classified by looking at the PSCs parallel and perpendicular backscatter ratio as well as the depolarisation ratio. The classification can then be used to understand the formation and composition of the cloud. To process the data gathered from the lidar a script in MATLAB is developed. The script is automatically going through the data and pinpointing the boundaries and interpolate the data, then using this to calculate the backscatter and depolarisation ratio. The script runs for all the available IRF observations between 2008 and 2018. The ratios and boundaries calculated from all the observations are then used to create a climatology. Comparing the climatology to the climatology by Blum et. al \cite{Psct} shows similar results. Future work should be done on the MATLAB program to inprove finding parameters from observation where the data includes more noise than the program can currently handle. This enables the retrieval of more trusty parameters and a more precise climatology.

The Arctic Summer Cloud Ocean Study expedition took place during the autumn of 2008 and brought back water and air samples. One theory was that marine particles were shot into the atmosphere by bubble bursting and, while in the atmosphere, acted as cloud condensation nuclei. Particles collected from the subsurface water, surface microlayer and just above the surface had their topography and morphology analyzed using a scanning electron microscope. Due to a lack of EDS analysis it's impossible to say for sure if the particles found were the same found in previous studies, just that it is highly likely that they are. No evidence against the marine particles being able to act as cloud condensation nuclei was found but the data gathered was not sufficient to strengthen the theory either. The scanning electron microscope was also used in a pedagogical study, analyzing how operators with different knowledge and prior experience interact with the microscope's images. These results as well as knowledge gained from literature studies were used to improve a high school experiment regarding centripetal acceleration. The main issue with the experiment was that what the students learned performing the experiment was not the same as the theoretical models the teachers wished the students to learn. The reason for this was because the experimental equipment lacked the centripetal model's external representations such as force arrows. If a simulator would be incorporated into the lab centripetal acceleration representations could be visualized and a clearer connection between experiment and theory could be made.

Wind atlases are interactive databases used extensively for preliminary wind resource assessment aimed at optimal wind power development. The selection and processing of wind atlas data are important and will determine the quality of the subsequent WRA (Wind Resource Assessment) phases. This study aims to compare, process, and interpret different wind atlases in determining effective wind resource analysis for 14 different sites in Sweden. The wind atlas data is accessed, parsed, and compared using multiple methodologies to ensure a fair comparison. Several variables like wind speed, wind direction, temperature, production values, etc. are analysed and compared amongst the wind atlas data. The corrected versions of the data are drawn out to conclude and determine how well those databases represent the realistic conditions in a forested site. The data is also compared and validated with measurement data. The results indicate several layers of insights into the wind resource regime. The preliminary results from 14 sites show that New European Wind Atlas (NEWA) and Global Wind Atlas (GWA) agreed sufficiently on the subject of the wind conditions for most of the sites. Methodologies like downscaling and long-term correction introduced to the wind atlas data provided more insights and proved that the database could expand and include more complex wind conditions in the coming years. Furthermore, the comparison and analysis of wind atlas data along with measurement data revealed that NEWA aligned the most to the actual wind conditions for a site. Several uncertainties are considered but more validation and thorough insights in the future could determine and give more affirmations to the idea put forward. Further studies could be conducted along with the inclusion of additional layers, variables, and databases to the wind atlases.

Mätningar av gränsskikt som utförts i Marsta (MAO) under tidsperioden 1 juli 1994 till 28 februari 1995 har analyserats. Mätningarna, som genomfördes på en 30 meter hög mast, omfattar bland annat vindhastighet, vindriktning och temperatur på 6 nivåer. Långvågig in- och utstrålning uppmättes på en höjd, vilket även gällde turbulenta fluktuationer av vindens 3 komponenter och temperatur. Den här redovisade undersökningen inriktades på studier av stabila gränsskikt. Dels studerades turbulensen samt hur temperaturavtagandet vid bildningen av ett stabilt gränsskikt varierar med tiden. Även specialfallet, när ett neutralt skikt bildas vid markytan i det stabila gränsskiktet mitt i natten, studerades. För undersökning av turbulensen har jämförelser mellan dessa mätdata och andra undersökningars mätdata genomförts. Jämförelsen har gjorts med hjälp av Monin—Obukhovs similaritetsteori vilket innebär att man studerar hur de dimensionslösa standardavvikelsern för u, v, w och T och den dimensionslösa temperaturgradienten beror av z/L. Resultaten visade att överensstämmelsen mellan denna och andra undersökningar var relativt god. Genom numeriska beräkningar har man tidigare funnit att temperaturen nära marken minskar med roten ur tiden de första 3-4 timmarna, då skiktningen blir stabil. Detta gäller vid konstant långvågsutstrålning. I den här undersökningen uppgick motsvarande tidsperiod till 45 minuter. En ekvation som beskriver hur det neutrala skiktets höjd växer har härletts. Denna ekvations giltighet har även testats. Resultatet var inte entydigt.

Measurements collected at Cabauw, the Netherlands, during the period November 1996 to May 1997, have been evaluated. The study was focused on the calculation of turbulence characteristics and profiles of wind speed and temperature under stable and near neutral conditions in the atmospheric surface-layer. Results from a 1-dimensional second-order closure model was compared with the outcome from the present observational data. The Monin-Obukhov similarity was applied for calculating the non-dimensional wind (Φm) and temperature gradients (Φh), the obtained result are: Φm = 0.9 + 4.4z/L and Φh = 0.9 + 3.6z/L. We suggest to replace the length scale kz, in the length scale of the definition of the Φ-functions, with the integral length scale, Λw, since Λw is more related to the length scale of the most energetic turbulent motions. On basis of the measurement campaigns performed, it was not possible to verify unique functions for these non-dimensional profiles, and therefore it is suggested that another length scale besides kz must be of importance. Furthermore, the balance between shear production, viscous dissipation and the buoyancy in the turbulent kinetic energy budget were investigated. The values of the non-dimensional standard deviations of horizontal and vertical velocities are constant with regard to stability and in good agreement with figures reported in the literature. By using a 1-dimensional second-order closure model it has not been possible to describe the turbulence characteristics of the stable atmospheric surface-layer. Three different combinations of constants are shown in this report, and they indicate problems that occur when comparing closure model results with experimental data from a stable stratified atmosphere.

This thesis will examine the local effects of land cover on icing forecasts. In Paper I, a single column model was used to test the sensitivity of icing forecasts to land cover fraction. Here, the ice accretion forecast was found to be highly sensitive to the wind magnitude response to the surface roughness. Diabatic effects related to the surface albedo played a secondary role, significant in cases with strong solar irradiance. Paper II examined the impact of 2-dimensional patterns of land cover heterogeneity on the effective surface roughness and blending height using large eddy simulation over a diurnal cycle of solar irradiance. The blending height--or the elevation at which the atmospheric response to the underlying land cover becomes horizontally homogeneous--has been proposed as a guide for coupling numerical weather models to surface parameterizations. In stable conditions, when the atmospheric boundary layer height was shallow, the blending height over surfaces with large heterogeneity length scale was found to be much lower than that of analytical models from previous studies. A new formula for a dynamic blending height was proposed taking this effect into account. The effective surface roughness was found to decrease with increasing land cover heterogeneity. The wind power response from an idealized wind turbine with 80-meter hub height to the effective surface roughness was shown, with a positive response in wind power with increasing land cover heterogeneity. The wind power response was smaller and less systematic with wind turbines extending above the blending height, further highlighting the utility of an accurate formulation for this variable. / I den här avhandligen undersöks de lokala effekterna av landtäcke på isbildningsprognoser. I artikel I användes en enkolumns-modell för att testa känsligheten hos isbildningsprognoser för olika andelar landtäcke. Här visade sig isbildningsprognosen vara mycket känslig för ytans påverkan på vindstyrkan. Diabatiska effekter relaterade till ytalbedo spelade en sekundär roll, speciellt i fall med stark solinstrålning. Artikel II undersökte hur  tvådimensionella mönster i landtäckets heterogenitet påverkade den effektiva ytjämnheten och blandningshöjden med hjälp av simuleringar av en stor virvel under en dygnscykel av solinstrålning. Blandningshöjden - eller den höjd vid vilken atmosfärens respons på det underliggande marktäcket blir horisontellt homogent - har föreslagits fungera som  guide för  hur man kan koppla numeriska vädermodeller till ytparameteriseringar. Under stabila förhållanden, när den atmosfäriska gränsskiktshöjden var låg, visade sig blandningshöjden över ytor med stor heterogenitetslängdskala vara mycket lägre än den från analytiska modeller från tidigare studier. En ny formel för att beräkna dynamisk blandningshöjd föreslogs med hänsyn till denna effekt. Den effektiva ytjämnheten visade sig minska med ökande heterogenitet i landtäcket. Responsen med avseende på den effektiva ytjämnheten visades för en ideal vindturbin med 80 meters navhöjd , med en ökning i vindkraftsproduktion med ökande heterogenitet i landtäcket. Påverkan på produktionen var både mindre i allmänhet och även mindre systematisk för vindkraftverk som sträckte sig över blandningshöjden, vilket ytterligare understryker behovet av en exakt formulering av denna variabel.

<p>Wind is used as an energy source all over the world. To be able to use this effectively, there is a need for as good forecasts and forecast models as possible. One of these models is Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®) that is used to calculate short time forecasts. This model is used here to calculate wind speeds at two different areas in Västra Götaland, Bengtsfors and Vänersborg. There are also wind measurements with SODAR stations for these areas. The first part of this work is to investigate the difference between two model resolutions, 36 and 12 km, for the model results compared with the measurements. The comparison is done by calculating some different statistical values. The results of these parameters show that the difference between the two resolutions is fairly small and that the lower resolution gives a slightly better result.</p><p>The second and major part of this work is to use two different regression models to adjust the result of the forecast models to the result of the measurements. These regression models will then be possible to use even when there are no measurements to compare with. The idea of these regression models is to find a way to describe the difference between the result of the forecast model and the SODAR measurements. This difference is then subtracted from the result of the forecast model so that you get an adjustment and more accurate result. The first regression model calculates the difference according to time of the day, the other model calculates the difference according to the wind speed.</p><p>Furthermore, the measurements used are taken from 75 meters height above the ground. These are then compared to some different results from the forecast model, for example different model heights and different resolutions, and also the model results adjusted with the regression models. The comparison is done by calculating the same statistic values as before, both with and without an adjustment with the regression models, and also to look at histograms that show the distribution of the difference. It is shown that with the regression adjustment, there is a clear improvement of the statistical values compared to the original results of the forecasts. For example the value of the absolute mean difference is reduced with approximately 0.4-0.7 m/s with an adjustment of the regression model. The histograms clearly show that a more even distribution occurs after the adjustment with the regression models. From having a major part of the differences at 1-2 m/s to now having the major part at around 0 m/s and furthermore there is also generally a lower difference between the measurements and the results from the forecast model.</p>