As wind farms continue to take up more land throughout Northern Europe, developers are looking to sparsely populated areas, particularly in northern Fennoscandia, which hosts strong winds but also mixed and patchy forests over complex terrain. The complexity makes wind resource assessments difficult, raising uncertainty and therefore cost. Computational fluid dynamics (CFD) has the potential to increase the accuracy and reliability of wind models, but the most common form of commercial CFD modeling, Reynolds averaged Navier-Stokes (RANS), makes limiting assumptions about the effect of the forest on the wind. The wind resource assessment and energy estimation tool WindSim® , developed by WindSim AS, utilizes a porous medium model of a homogeneous forest with the influence of the forest on the airflow as a drag force term in the momentum equations. This method has provided reliable wind speed results but has been less reliable in estimating turbulence characteristics. The measure we evaluate in this study is turbulence intensity (TI). In this investigation, we make two types of modifications to the model and evaluate their impact on the TI estimates by using a benchmark data set collected by Meroney [1]. The first method is a variable profile of leaf area index (LAI) to represent the physical shape of the forest more accurately, and the second is a series of modifications to the closure coefficients in the turbulence transport equations. These modifications focus on the work of Lopes et al. [2], who used a large eddy simulation (LES) model to show that the turbulence production terms originally proposed by Green [3], expanded upon by Sanz [4], and widely used in the industry are unnecessary. Our investigations found that the implementation of a variable LAI profile has a small but non-negligible effect and that the elimination of the production terms from the turbulence transport equations does lead to a significant reduction in TI immediately above the forest. Both methods have minor effects on wind speed estimates, but the modification of closure coefficients has a much more significant impact on the TI. The coefficients proposed by Lopes et al. [2] drastically reduce TI estimates, but the model is still unable to reflect the Meroney data throughout the forest. Continued modification to new closure coefficients in combination with a variable forest LAI and other modifications such as a limited length scale may lead to significant improvement in TI estimates in future models, but these modifications must be compared against real-world data to ensure their applicability.

The Antarctic sea ice region is relatively stable in extent from year to year and sees little long-term variability, the primary driver for its seasonal advance and retreat being the seasonal changes in advection of heat through the atmosphere. However, observations show a slight positive trend in its extent over recent decades. Recent work has built on the hypothesis that anomalous poleward moisture fluxes could be seen in concert with anomalous decreases in sea ice variability by providing evidence of this correlation in the Arctic sea ice region. In order to test this hypothesis and to investigate the atmospheric circulation patterns during states of low sea ice concentration in the Antarctic, records of de-seasonalized sea ice concentration anomalies are made for five regions of the Antarctic polar region, and composite distributions of variables of atmospheric circulation for the lowest 10th percentile of months with low mean sea ice concentration are compiled. Meridional moisture fluxes from these composites are tested against the entire population of meridional moisture fluxes using the Student's t-test with a confidence level of 95%, and the differences from the overall mean fields for atmospheric conditions during these cases are calculated. Of the five regions, the Ross Sea, Weddell Sea, and Pacific Ocean sections exhibit significant local moisture flux anomalies in the direction of the pole during months with low sea ice concentration, supporting the hypothesis that moisture transport into the polar region is important for the variability of sea ice in the Antarctic. The Bellingshausen - Amundsen Seas and Indian Ocean sectors show weak local signals of poleward moisture fluxes, indicating that there are other varying factors affecting the sea ice more heavily in these regions. Mean geopotential height anomalies during months with anomalously low sea ice concentration indicate that the Weddell Sea and Pacific Ocean regions are coupled with the positive phase of the Southern Annular Mode, while low sea ice concentration in the Indian Ocean as well as the Bellingshausen and Amundsen Seas regions show concurrence with the negative phase. With general circulation models predicting a persistence of the positive phase of the Southern Annular Mode in a warming climate, it is important to understand how the Antarctic sea ice region responds to the phase of this oscillation.

Convective snow bands forming over the Baltic Sea can result in heavy precipitation along the Swedish east coast. Forecasting these events well is of great importance to prevent road traffic injuries, increased pressure at hospitals and cancelled bus traffic. This thesis project aims to evaluate the performance of the high-resolution non-hydrostatic convection permitting model HIRLAM ALADIN Reasearch on Mesoscale Operational NWP In Euromed (HARMONIE) in simulating convective snow bands. Its horizontal respresentation of precipitation rates, area, placement and timing was examined in a case study of two events. The case of 2007 during the 12-14th of November, formed over the Gulf of Finland and resulted in Nynäshamn receiving ≥ 55 mm precipitation during the 37 hours long event. Areas south of this precipitation maxima also recieved heavy precipitation. The second case, 21-23rd of March 2008, formed over the Gulf of Bothnia during north-easterly  winds and resulted in a total precipitation of 10 mm at Gävle. The precipitation maxima was observed offshore, north of Gävle, with ≥ 16 mm precipiation in 34 hours. Convective snow bands were also observed over Vänern and Vättern in both cases.  HARMONIE simulated convective snow bands well in terms of intensity, timing, placement and area, in both cases, compared to datasets from radar, radar with merged gauge data and separate observational data from weather stations. Areas south of the local maxima at Nynäshamn in the case of 2007 were however overestimated by a total of 10-15 mm, most likely due to a simulated shift in wind direction during some of the most intense hours. In the case of 2008 the model also captured weak convective snow bands at Vänern and Vättern accurately in terms of precipitation area, timing and accumulated precipitation. Further case studies of snow bands are however necessary to obtain a more comprehensive view of the performance of HARMONIE.

As the wind industry is developing, it is asking for more reliable short-term wind forecasts to better manage the wind farms’ operations and electricity production. Developing new wind farms also requires correct assessments of the long-term wind potentials to decide whether to install a wind farm at a specific location. This thesis is studying a new generation of numerical weather forecasting models, named mesoscale models, to see how they could answer those needs. It is held at the company Maïa Eolis which operates several wind farms in France. A mesoscale model, the Weather Research and Forecasting model (WRF), was chosen and used to generate high resolution forecasts based on lower resolution forecasts from NCEP’s Global Forecasting System. The stages for implementation of daily forecasts for the company’s wind farms were: explore and configure the model, automate the runs, develop post-processing tools and forecasts visualization software which was intended to be used by the management team. WRF was also used to downscale wind archives of NCEP’s Final Analysis and determine the possibility to use these in assessing wind potentials. Finally the precision of the model in both cases and for each wind farm was assessed by comparing attained data from the model with real power production.

Turbulent fluxes govern the exchange of momentum, heat and moisture between the Earth’s surface and the overlying air. Computations of these fluxes are crucial, particularly over lakes and seas because most of the earth’s surface consists of water. One of the most common methods of calculating turbu- lent fluxes is the bulk method, where the fluxes are expressed with exchange coefficients. With more knowledge of these coefficients, the fluxes can be determined with a higher accuracy. Consequently, the turbulence structure and the exchange of moisture, momentum and heat between the surface and the overlying air can be better understood. The goal of this study was to compute the neutral exchange co- efficients for drag (CDN), heat (CHN) and moisture (CEN) and investigate their dependency on various atmospheric conditions, based on four years of measurements from Lake Erken, located about 70 km east of Uppsala. The coefficients were evaluated against the wind speed, stratification and time over water TOW (the time that the air is above the water before it reaches the tower). A special analysis was done by studying the variation of the coefficients with the wind speed during the UVCN-regime. Another analysis was done to see if the coefficients may have been influenced by non-local processes, e.g. advection from the surroundings. Additionally, normalized standard deviations for the temperature and humidity were evaluated for different stabilities. The results were compared with estimations by the COARE3.0 algorithm (for the dependency on the wind speed and the stability) in a previous report and other earlier studies.  The results indicated that the neutral exchange coefficients were higher and more dispersed during near neutral stratification and low TOWs. The normalized standard deviations also increased during neutral conditions. The explanation for this could be related to the presence of the UVCN-regime or non-local effects such as advection or entrainment from the surroundings. The wind speed had no ob- vious impact on the coefficients. However, the drag coefficient was larger and more spread out in the wind speed range 1-3 m/s. In comparison to earlier studies, the exchange coefficients were higher and scattered to a greater extent. This may be because of a strong UVCN-regime, sustainable non-local influences, relatively steeper waves than open-sea conditions or outliers in the data.

Syftet med den här studien är att undersöka om och hur turbulensstrukturen i ytskiktet påverkas av den interna gränsskiktshöjden. Mätningar gjorda 1984 och 1988 på Näsudden på sydvästra Gotland har använts. Vindriktningen har valts så att vinden har en så lång och ostörd anloppssträcka över hav som möjligt. Höjden på det interna gränsskiktet har tagits fram ur temperaturprofiler, där den första inversionen representerar den interna gränsskiktshöjden. Monin-Obukhovs similaritetsteori har använts som stomme i undersökningen. Undersökningen har visat att vissa turbulensfaktorer i ytskiktet följer Monin- Obukhovs teori bättre än andra. Den interna gränsskiktshöjden påverkar främst vindstrukturen. Till viss del påverkas även temperaturstrukturen. I vissa fall kan även den karakteristiska hastigheten i övergångsskiktet påverka turbulensen i ytskiktet. Horisontella vindvariansen, bör t.ex. normaliseras med denna hastighet och inte med friktionshastigheten som Monin-Obukhovs teori föreskriver. Vertikalvindvariansen i ytskiktet kan normaliseras med både friktionshastigheten och den karakteristiska hastigheten i övergånsskiktet, och således både med höjden över marken och den interna gränsskiktshöjden. / The aim of this study is to find out if and how the height of the internal boundary layer affects the structure of the turbulence in the surface layer. This has been done from measurements made 1984 and 1988 at Näsudden on the southwest part of Gotland. The wind direction has been chosen to get as long fetch over sea as possible. The height of the internal boundary layer is obtained from temperature profiles where the first inversion represents the height of the internal boundary layer. The Monin- Obukhov similarity theory has been used as a frame in this investigation.   The study has shown that some turbulence features follow the Monin-Obukhov similarity better than others. The height of the internal boundary layer mostly affects the wind structure, but partly also the temperature structure. In some cases the characteristic velocity in the mixed layer also influences the turbulence in the surface layer. For example, it is better to normalize the horizontal wind variance with this velocity than the friction velocity as proposed in Monin-Obukhov theory. To normalize the vertical wind variance in the surface layer, it is possible to use both the friction velocity and the characteristic velocity in the mixed layer. This means the vertical wind variance can be normalized with both the height above ground and the height of the internal boundary layer.

The Carbon dioxide (CO2) concentration in the atmosphere has increased dramatically since the start of the industrialisation. The effects that the increase of CO2 has on the future climate are still not fully investigated. CO2 in the atmosphere contributes to the, for all life on earth, necessary greenhouse effect. It is confirmed that higher CO2 concentration in the atmosphere increases the green house effect, which results in higher temperature. The main source to the increase of CO2 is burning of fossil fuels. The change in land use is also a contribution to the increase of the CO2 concentration in the atmosphere. The largest sinks of CO2 are organic consumption and oceanic uptake. The organic consumption of CO2 varies a lot at higher latitudes due to the difference in vegetation between the seasons. During the warmer seasons the consumption of CO2 is large and during the winters the consumptions of CO2 is practically zero. The ocean uptake of CO2 varies also a lot during the year because the CO2 dissolves more easily in cold water. The purpose of this study is to analyse CO2 concentration and air-sea fluxes of CO2 measured at Östergarnsholm, a small flat island east of Gotland in the Baltic Sea, and compare the results to previous studies. The CO2 concentration data was collected between 1997 – 1999 and 2001 – 2003. The CO2 flux data was collected between 2001 and 2003. The analysis of the CO2 concentration showed that for the period 1997 to 1999, the CO2 concentration at Östergarnsholm was lower than for the reference series from a Polish site in the Baltic Sea. A correction was made by adding 27 ppm to the Östergarnsholm series. The annual fluctuations of CO2 concentration at Östergarnsholm are significant (about 40 ppm). During the summer 1998, the expected decrease was not as large as it should be because of the El Niño outbreak 97/98 and the locally cold and rainy summer. The direct measured CO2 fluxes were corrected with the well known Webb correction before they were analysed. The CO2 fluxes are wind dependant – higher wind speed give higher CO2 flux. The CO2 fluxes are also dependant of the difference in partial pressure between the air and the water. Parameterised CO2fluxes were calculated and compared to the direct measured CO2 fluxes. The parameterisations use a quadratic as well as a cubic wind dependency. To calculate the parameterised CO2 fluxes, a fixed value of the difference in partial pressure between the air and the water was used because the CO2 in the water was not measured. The parameterised CO2 fluxes wind dependency agreed with the direct measured CO2 fluxes. / Koldioxid(CO2)-koncentrationen i atmosfären har ökat stadigt sen början av industrialiseringen. Effekten som de ökade CO2-halterna kommer ha på framtidens klimat är ännu inte helt utrett. CO2 bidrar till den livsviktiga växthuseffekten. Det är en ökning av växthusgaser, bland annat CO2, som leder till en ökning av växthuseffekten. Ökad växthuseffekt leder till högre temperatur på jorden. Den största ökningen av CO2 i atmosfären beror på förbränning av fossila bränslen. Även förändringen i markanvändning leder till ökade halter av CO2. De största sänkorna av CO2 är den organiska konsumtionen av CO2 och havens upptag av CO2. Den organiska konsumtionen av CO2 varierar mycket under året och är som störst under de varmare månaderna. Havens upptag av CO2 varierar också mycket under året eftersom havens förmåga att lösa CO2 beror på vattnets temperatur. Syftet med den här studien är att analysera CO2-koncentrationen och CO2-flödena mellan hav och luft på Östergarnsholm, en liten, låg ö öster om Gotland. Resultaten jämförs med tidigare studier. CO2-koncentrationsdata samlades in mellan 1997 – 1999 och 2001 – 2003. CO2-flödesdata samlades in mellan 2001 och 2003. Analysen av CO2-koncentrationen visar att under perioden 1997 till 1999 är CO2- halterna för låga på Östergarnsholm. En korrektion gjordes genom att lägga till 27 ppm till de uppmätta CO2-halterna. Årsvariationerna av CO2-halterna är mycket tydliga men sommaren 1998 sjunker inte CO2-halten till så låga värden som de borde vara. Att CO2-halterna inte sjönk mer beror dels på El Niño-utbrottet 97/98 och dels på den lokalt kalla och regniga sommaren. De direkt mätta CO2-flödena korrigerades med hjälp av den välkända Webbkorrektionen innan de analyserades. CO2-flödena är beroende av vindhastigheten – högre vindhastighet ger högre CO2-flöden. CO2-flödena beror också på skillnaden i CO2-halt mellan luften och havet. Parameteriserade CO2-flöden beräknades och jämfördes med de direkt mätta CO2-flödena. De parameteriserade CO2-flödena beräknas antingen med kvadratiskt eller kubiskt vindberoende. För att beräkna parameteriserade CO2-flöden användes ett fast värde på skillnaden i CO2-halt mellan luften och vattnet eftersom CO2-halten i vattnet inte mäts. De parameteriserade CO2- flödenas vindberoende stämde överrens med de direkt mätta CO2-flödena.

Weather forecasting relies on the availability of observational data as input parameters. However,such data are not readily available, because of difficulties to collect weather data due toinaccessibility to many places in the world, such as oceans or mountain regions. For this reason,satellite surveillance is a suitable tool to observe the atmosphere in regions where it is notpossible by other means. This master thesis is a study of convective cloud cluster formation over Thailand, conductedthrough satellite image analysis. Characteristics of cloud cluster formations are investigatedthrough an implementation of the Maximum Spatial Correlation Technique (MASCOTTE),described by Carvalho and Jones (2001). This method allows tracking of convective cloud systemsthrough region based analysis of satellite images. The aim of this study is to investigate whether satellite image analysis, through the implementationof the MASCOTTE methodology, can provide characteristics of convective cloud systems,in order to discern convective systems by intensity, accurately enough to be able to discernsevere thunderstorms from ordinary thunderstorms. The annual distribution of the occurrenceof life cycles detected through the analysis is studied, as well as their monthly distribution ofmean and maximum life times. Moreover, the yearly distribution of life cycle mean and minimumbrightness temperatures are analysed, as well as the number of detected split and mergeevents. This is followed by a comparison of life cycle structural properties to investigate thepossibility to use individual parameters, alone or in combination with each other, as indicatorsof the degree of convective activity within life cycles. Yearly distributions were studied in order to verify if this method could reveal seasonal variations,such as the onset period of the wet season, in terms of the occurrence of life cycles andtheir life time. The findings of this study verified that the most convectively intense life cycles exist under theinfluence of the Inter Tropical Convergence Zone (ITCZ), during the onset and beginning ofthe monsoon season. Analysis of life cycle structural properties, showed that properties likemean and minimum brightness temperature as well as fractional convective area, could be usedas indicators to discern between life cycles with different level of convective activity. However,it is concluded that studies, including ground-based remote sensing technologies such asRADAR/LIDAR, as well as data from rawinsondes, needs to be conducted in order to clarifyif it is possible to use this methodology to successfully discern severe thunderstorms fromordinary thunderstorms. / Tillgängligheten av meteorologiska mätdata är väsentlig för att kunna prognostisera väder. Idag är tillgängligheten på dessa data relativt gles, bland annat på grund av svårigheter att mäta på många platser runt om i världen, t.ex över världshaven eller vid otillgängliga bergsområden. Därför är satellitövervakning ett bra alternativ till andra typer av väderobservationer, eftersom denna teknik kan tillhandahålla mätdata över stora områden som annars inte är möljiga att samla data från. Denna magisteruppsats är en studie om egenskaper hos konvektiv molnbildning över Thailand. Studien är genomförd med hjälp av satellitbildsanalys. Egenskaper hos olika konvektiva molnceller har studerats genom att använda en metod baserad på ”the Maximum Spatial Correlation Technique” (MASCOTTE), beskriven av Carvalho and Jones (2001). Tanken bakom denna metod är att hitta och följa utvecklingen av olika konvektiva molnceller baserat på deras storlek och temperatur. Målet med studien är att undersöka hurvida denna metoden kan ge kunskap som leder till att man kan skilja på konvektiva celler, genom intensitetsskillnader, med tillräcklig noggrannhet för att kunna urskilja vanliga konvektiva celler från intensiva celler. För att få en uppfattning om förekomsten av intensiva konvektiva system, har antalet detekterade livscykler per månad studerats. För sedan att få en bild av hurvida deras livscykler skiljer sig åt över året, har även egenskaper som medellivslängd och maximal livslängd studerats. Dessutom studerades den årliga fördelningen av livscyklernas medel och minimum temperaturer, samt förekomsten av delningar och sammanslagningar av konvektiva celler. För att finna kunskap om skillnader i intensitet mellan individuella livscykler, har egenskaper som medel och minimum temperatur analyserats. Dessutom har andelen moln med extremt låg temperatur studerats i syfte att kunna använda dessa parametrar som intensitetsindikatorer vid satellitbildsanalys. Resultaten i denna studie visar att de mest intensiva konvektiva molnsystemen (kraftigaste åskvädren), förekommer under påverkan av ITCZ (Inter Tropical Convergence Zone), under antågandet och början av regnperioden. Studier av de konvektiva systemens egenskaper visade att parametrar, som andelen extremt kallt område i molnceller (fractional convective area), och livscyklernas medel och minimum temperaturer, skulle kunna användas som intensitetsindikatorer för att skilja på olika livscykler med avseende på deras styrka i intensitet. Slutsatsen av studien är att det behövs fler studier där andra typer av meteorologiska mätdata, såsom RADAR/LIDAR och sonderingsdata är involverade, för att skaffa ytterligare kunskap om hur man genom satellitbildsanalys kan urskilja kraftiga åskväder.

Measurements of turbulent fluxes (momentum, sensible heat, latent heat and CO2) at two different heights were studied from data of a tower at Ostergarnsholm Island (Baltic Sea) during one week, while calculations using bulk formulations of fluxes were done with measurements in the tower and in two buoys moored at different locations. Different behaviors are found for the different fluxes. Measured latent heat flux shows higher correlation with calculations than measured sensible heat flux. For the CO2 flux, this relation was not found. Also all measured fluxes at the tower agree better with calculations when they are done under unstable conditions, meaning that the tower is better measuring the area where the measurements are taken in the buoys (near the tower). The studied period includes an upwelling and a high horizontal surface heterogeneity was found during most of the periods. It was seen using the comparison between calculated and measured fluxes and also using satellite images of the studied site. The footprint area is the area at some distance upwind from the tower where the surface conditions are influencing the measurements of the flux of some quantity at certain height in the tower, and this footprint area is continuously changing because its highly dependence with the stratification. Since during all the period the stratification was changing from slightly stable to slightly unstable conditions, the surface heterogeneity can also be seen in the variability of measured fluxes at different heights. One important conclusion in the study is that calculations of the fluxes using bulk formulations may not be useful when high variability of different parameters (as sea surface temperature and pCO2w ) is expected, as for example during upwelling situations and near coast, where the phytoplankton can significantly influence the concentration of CO2 at the surface. A wide study is done, including meteorological and oceanographic parameters, fluxes, comparisons, relations with parameters, transfer coefficients, dependences with the stratification and satellite images. / Mätningar av flöden (impuls, värme, vattenånga och CO2) vid två olika höjder studerades med data från en mast på ön Östergarnsholm (i Östersjön) under en vecka, beräkningar av flödena gjordes med mätningar av atmosfäriska parametrar från samma mast samt data från två bojar på två olika platser. Man fann olika beteenden för de beräknade och uppmätta flödena. Direkt (sensibelt) värme visade högre korrelation mellan beräkningar och uppmätta sensibla värmeflöden . För CO2- flödet fann man inte detta samband. För alla flödena överensstämmer mätningarna bättre med beräknade flöden när de är gjorda under instabila förhållanden, vilket betyder att under dessa förhållanden representerar mätningarna i masten bättre området där bojarna är placerade. Den studerade perioden inkluderar en period med upvällning (upwelling) och en hög horisontell variabilitet i ytparametrar under den största delen av denna period. Detta visades genom jämförelser mellan de beräknade och de uppmätta flödena och även genom satellitmätningar. Det område uppvind masten där ytan påverkar flöden uppmätta i masten på en viss nivå kallas ”footprint area”, och denna footprint area förändras kontinuerligt på grund av det stora beroendet av skiktningen i atmosfären. Eftersom skiktningen under hela perioden förändrades från något stabilt till något instabilt, kan ytvariabiliteten även ses i variationen av uppmätta flöden på olika höjder. En viktig slutsats i studien är att beräkningar av flödena som görs med standardformler inte bör användas vid förhållanden med hög horisontell och vertikal variation av olika parameter (som havsytetemperatur och pCO2w), som till exempel under uppvällningssituationer och nära kusten, där phytoplankton markant kan påverka koncentrationen av CO2 vid ytan. Studien inkluderar meteorologiska, oceanografiska parametrar, flöden, samband med parametrar, överförings koefficienter, beroende av stabilitet och satellitbilder. / Flujos turbulentos (momento, calor sensible, calor latente y CO2) en 2 alturas diferentes fueron estudiadas usando medidas de una torre en la Isla de Östergarnsholm (Mar Báltico) durante una semana. Los flujos también fueron calculados usando formulaciones con medidas de la torre y de dos boyas ancladas en diferentes localizaciones. Diferentes características para los distintos flujos fueron encontradas. El flujo de calor latente muestra una relación más alta con los cálculos que el flujo de calor sensible. No se encontró esta relación para el flujo de CO2. También, todos los flujos medidos en la torre coinciden mejor con los flujos calculados cuando estos son hechos bajo condiciones de estratificación inestable, significando que la torre mide mejor el área donde son cogidas las medidas en las boyas (cerca de la torre). El periodo estudiado incluye un afloramiento costero y se encontró una alta heterogeneidad horizontal en la superficie del mar durante la mayoría de los periodos. Esto fue estudiado usando las comparaciones entre flujos calculados y medidos y también usando imágenes de satélite. El footprint area puede ser definido como el área a una distancia desde la torre hacia donde sopla el viento donde las condiciones de la superficie influyen las medidas del flujo de alguna cantidad en la torre, y este footprint area está continuamente cambiando debido a su alta dependencia con la estratificación. Durante todo el periodo la estratificación estuvo cambiando desde ligeramente estable a ligeramente inestable, y por ello la heterogeneidad de la superficie puede ser vista en la variabilidad de los flujos medidos a diferentes alturas. Una conclusión importante en este estudio es que los cálculos de los flujos usando formulaciones podrían no ser útiles cuando se espera una alta variabilidad de los diferentes parámetros (temperatura superficial del mar y pCO2w), como por ejemplo durante situaciones de afloramiento y también cerca de costa, donde el fitoplancton puede influenciar significativamente la concentración de CO2 en la superficie. Se presenta un amplio estudio, incluyendo parámetros meteorológicos y oceanográficos, comparaciones de flujos, relaciones con parámetros, coeficientes de transferencia, dependencias con la estratificación e imágenes de satélite.

The wind industry is always seeking ways to better understand the performance of a wind turbine and improve its efficiency. During the operation phase and maintenance, wind turbines go through regular optimization. Due to the regular change in wind speed and direction, wind turbines need to be regulated and positioned accordingly. For a specific wind speed, there are a specific set of pitch angle positions. The study aims to quantify the errors in pitch angle positions and validate how much would the loss be if it deviates from its ideal pitch angle position. In this study, airfoil data from an NREL 5 MW turbine is used. Qblade is used in the simulation for error estimation. The simulation is based on BEM theory. A wind turbine blade is developed based on the given airfoil data. Multi-parameter BEM simulation is conducted for a range of wind speed, pitch angle, and rpm. Later the ideal pitch angle position for each wind speed bin is recorded. During the simulation process, downscaling the 5 MW to a 1.5 MW turbine was executed. Validation of the downscaling method was also executed. It showed good agreement with the obtained SCADA data of a working turbine. Later, pitch angle errors are introduced in the simulation.  The results are presented in two cases. Case 1 showed that at below-rated wind speed, there is a significant loss in power production if the error in pitch angle up to 1 degree.  Case 2 also shows error up to 5 degrees in region 2. This study contributes to a better understanding of the effect of pitch angle errors and their loss of power. This study took into account steady wind condition only and does not include climatic conditions or turbulence. A further study focusing on simulating in a high-fidelity setting, including real-time wind or topography conditions, is recommended to achieve a further understanding of the pitch angle errors in a wind turbine.