The profitability from the production wind power energy is related to the quality of the wind speed forecasts. All wind predicting methods needs meteorological data, for the prevailing synoptic situation, as input. High quality input is wanted for a better result. In this study a new idea of a method for estimation of high resolution wind fields is examined. The idea is to use an existing database, containing simulations of high resolution wind fields, to estimate the actual wind by combining the simulations in a way fitting actual synoptic data. The simulations in the database have been produced by the mesoscale MIUU-model, which has been developed by Leif Enger at Uppsala University. The database contains simulations characterized by different geostrophic wind speeds and directions. There is also a separation into four seasons, where values which are typical for each season is put on meteorological parameters. Reanalysis data from NCEP-NCAR, containing 850 hPa geopotential heights describing actual synoptic situations, is used to calculate geostrophic wind speeds and directions. Three different geostrophic wind calculation methods, the triangle method, the small cross-method and the large cross-method, are tested. The calculated geostrophic wind is compared between the methods. The small cross-method is chosen and the main reason for that is the large amount of reanalysis information considered by this method and the use of a small calculation area. Measurements of the wind speed and direction are available from the tower at Utgrunden. The geostrophic wind speeds and directions are therefore calculated especially for the position of Utgrunden. This is done by a linear weighting of data, from several grid points close to Utgrunden, with respect to the distance to Utgrunden. Linear weighting is also used when estimating the wind speed for Utgrunden. The wind speed is estimated by weighting together MIUU-model simulations, for different geostrophic wind speeds and directions, so that they fit the geostrophic wind values calculated for Utgrunden. The calculated wind speed, measured wind speed and calculated geostrophic wind speed, for Utgrunden, are compared. The correspondence, between the calculated and measured wind speed, turns out to be quite good for many time periods. The diurnal variations in the measured wind speed are partly captured by calculated wind speed, but the diurnal variations tend to be larger in the measured wind speed then in the calculated. There are also cases where there are large differences between the measured and estimated wind speed. Many of these cases are probably cased by unusual weather situations. By considering additional parameters, as the temperature field, it is likely that these wind estimations can be improved. With more research it may be possible to produce high resolution wind fields with enough accuracy to be useful as inputs in wind prognostic systems. The advantage with such a method would be that accurate high resolution wind fields could be produced without the use of a time consuming numerical high resolution model. / Lönsamheten för produktion av vindkraft elektricitet bestäms delvis av förmågan att göra bra vindprognoser för nästkommande dygn. Alla metoder för vindprognostisering behöver meteorologisk indata som beskriver den rådande synoptiska situationen. Kvaliteten och upplösningen på dessa indata har stor betydelse för metodens resultat. I denna studie undersöks en alternativ metod för bestämning av högupplösta vind fält. Idén är att man ska försöka utnyttja en tillgänglig databas av högupplösta vindfält, producerade av den mesoskaliga MIUU – modellen som är utvecklad av Leif Enger på meteorologiska institutionen vid Uppsala Universitet. Tanken är att dessa vindfält ska kunna kombineras på ett sådant sätt att de överensstämmer med en given synoptisk situation. MIUU – modell körningarna, i databasen, är indelade i situationer karaktäriserade av olika värden på den geostrofiska vindstyrkan och vindriktningen. Körningarna är gjorda för fyra säsonger, för vilka typiska värden för säsongen är satta på styrande parametrar. För att kunna kombinera MIUU - modell körningarna beräknas den geostrofiska vinden från 850 hPa geopotential höjd återanalys data tillgänglig från NCEP-NCAR. Tre olika beräkningsmetoder för geostrofisk vind testas och jämförs. Den ”lilla korsmetoden” väljs för uppgiften beroende på att den utnyttjar en förhållandevis stor mängd återanalys data, för beräkning av geostrofisk vind, samt använder litet beräkningsområde. Automatiskt uppmätta värden över vindhastighet och vindriktning finns tillgängliga från en mast positionerad vid Utgrunden i Kalmar sund. Den geostrofiska vinden beräknas därför i Utgrundens position. Beräkningen utförs genom linjär viktning av data från de från Utgrunden sett fem närmaste gridpunkterna (i lilla korsmetodens gridfält). En linjär viktning används sedan även för att vikta ihop de MIUU – modell simulerade vindfälten så att de passar de beräknade värdena på geostrofisk vindhastighet och vindriktning. Jämförelser görs mellan den beräknade vinden, den uppmätta vinden samt den geostrofiska vinden, för Utgrunden. Korrelationen, mellan uppmätt och beräknad vind, visar sig vara ganska god periodvis. Den dagliga variationen i den uppmätta vindhastigheten fångas delvis av beräkningsmetoden, men dygnsvariationen är betydligt större i den uppmätta vinden än i den beräknade. Det noteras även att det finns situationer då det är stora skillnader mellan beräknad och uppmätt vind. Dessa situationer beror i många fall troligen på onormala vädersituationer. Studium av ytterliggare parametrar, som t.ex. temperaturfältet, skulle troligen leda till betydande förbättringar i vinduppskattningen. Ytterligare forskning och förbättring av metoden skulle kunna leda till produktion av högupplösta vindfält med tillräcklig kvalitet för användning i vindprognostiseringsmodeller. Fördelen skulle i så fall vara möjligheten att kunna producera högupplösta vindfält utan användning av tidskrävande numerisk modeller.

O objetivo principal deste trabalho é avaliar a capacidade do modelo RegCM3 (Regional Climate Model versão 3), para três diferentes simulações, em simular os padrões espaciais de tendência de alguns índices climáticos anuais e sazonais de temperatura e chuva na América do Sul para o clima presente (1961-1990). Para atingir o objetivo principal, desenvolveu-se um algoritmo baseado no software RClimDex para calcular os índices e investigou-se a habilidade dos dados de reanálise do NCEP/NCAR e do conjunto de dados de chuva produzido por Liebmann e Allured (2005) em estimar os índices anuais e sazonais de temperatura e chuva para a mesma região e período. A metodologia concentrou-se em análises dos coeficientes de correlação e de regressão linear. De maneira geral, os dois conjuntos de dados foram considerados válidos para representar os índices anuais e sazonais de temperatura e chuva observados na América do Sul durante o período de 1961-1990. Contudo, a reanálise do NCEP/NCAR mostrou sinais de tendência opostos às observações para os índices de temperatura e chuva sobre a Argentina. Dentre as três simulações com o modelo RegCM3, as simulações RegCM3(s2), com o esquema de convecção Emanuel, e RegCM3(s1), com o esquema de Grell, apresentaram um melhor desempenho em representar as tendências dos índices de temperatura e chuva, respectivamente, sobre a América do Sul. O modelo RegCM3(s1) simulou a predominante tendência de aumento das condições de umidade observadas na América do Sul através dos índices anuais r95p, prcptot e rx5day, particularmente na estação de inverno. As tendências opostas dos índices anuais cwd e cdd, que sugerem um aumento no número de dias com chuva, ao contrário, não foram bem detectadas pelo modelo RegCM3(s1). O aquecimento da temperatura mínima como conseqüência do aumento de noites quentes e diminuição de noites frias identificado em quase todo o continente foi simulado corretamente pelo modelo RegCM3(s2). Com relação à temperatura máxima, embora as observações não apresentem um padrão característico, a simulação do modelo RegCM3(s2) se mostra bastante semelhante ao apresentado pela reanálise do NCEP/NCAR. As distribuições espaciais de tendência dos índices anuais de temperatura e chuva resultantes das simulações do RegCM3(s2 e s1, respectivamente) e do HadAM3 sobre a América do Sul durante o período de 1961-1990 são bastante semelhantes entre si, embora o HadAM3 seja caracterizado por tendências mais suavizadas. Para os índices anuais e sazonais de temperatura, a simulação do HadAM3 se mostrou ligeiramente melhor à do RegCM3, enquanto que o inverso é encontrado para os índices anuais e sazonais de chuva. / The main goal of this study is to investigate if the RegCM3 model (Regional Climate Model version 3) is able to simulate the spatial patterns of some annual and seasonal climate indices of temperature and precipitation trend over South America for the present climate (1961-1990). The analysis is done for three different simulations where the model was running with different cumulus parametrization, i.e, Grell and Emanuel. An algorithm based on the software RClimDex was developed to calculate the indices. Different data sources such as the NCEP/NCAR reanalysis, individual observational stations and others were used to estimate the annual and seasonal indices of temperature and precipitation for the same region and period. Correlation and linear regression coefficients analysis were used in the results comparison. In general, the results suggest that the datasets can provide useful information about annual and seasonal indices of temperature and precipitation at individual grid cells in South America during the period 1961-1990. However, the NCEP/NCAR reanalysis showed reversal trend signals for some indices over Argentina. Within the three simulations with the RegCM3 model, the trends of the annual and seasonal indices of temperature and precipitation over South America are better reproduced by the Emanuel (s2) and Grell (s1) schemes, respectively. The RegCM3(s1) simulates the change to wetter conditions in South America through the r95p, prcptot and rx5day annual indices, particularly in the austral winter. On the other hand, the opposite signal of the trends in cdd and cwd indices, that indicates an increase in the number of days with precipitation, was not well represented by the model. The warming in minimum temperature as a consequence of the increase in the frequency of warm nights and the decrease of cold nights observed all over the South American continent was correctly simulated by the RegCM3(s2). Although the observed maximum temperature extremes did not show any special feature, the simulations with Grell scheme were able to represent the spatial patterns of the warm and cold days indices trend similar to the NCEP/NCAR reanalysis. The spatial distributions of the annual indices of temperature and precipitation trend obtained from the RegCM3(s2 and s1, respectively) and HadAM3 simulations over South America during the period 1961-1990 are very similar, though the HadAM3 shows a trend less intense. For the annual and seasonal indices of temperature, the HadAM3 simulation is slightly better than the RegCM3 running, while the opposite is found to the annual and seasonal indices of precipitation.

O objetivo principal deste trabalho é avaliar a capacidade do modelo RegCM3 (Regional Climate Model versão 3), para três diferentes simulações, em simular os padrões espaciais de tendência de alguns índices climáticos anuais e sazonais de temperatura e chuva na América do Sul para o clima presente (1961-1990). Para atingir o objetivo principal, desenvolveu-se um algoritmo baseado no software RClimDex para calcular os índices e investigou-se a habilidade dos dados de reanálise do NCEP/NCAR e do conjunto de dados de chuva produzido por Liebmann e Allured (2005) em estimar os índices anuais e sazonais de temperatura e chuva para a mesma região e período. A metodologia concentrou-se em análises dos coeficientes de correlação e de regressão linear. De maneira geral, os dois conjuntos de dados foram considerados válidos para representar os índices anuais e sazonais de temperatura e chuva observados na América do Sul durante o período de 1961-1990. Contudo, a reanálise do NCEP/NCAR mostrou sinais de tendência opostos às observações para os índices de temperatura e chuva sobre a Argentina. Dentre as três simulações com o modelo RegCM3, as simulações RegCM3(s2), com o esquema de convecção Emanuel, e RegCM3(s1), com o esquema de Grell, apresentaram um melhor desempenho em representar as tendências dos índices de temperatura e chuva, respectivamente, sobre a América do Sul. O modelo RegCM3(s1) simulou a predominante tendência de aumento das condições de umidade observadas na América do Sul através dos índices anuais r95p, prcptot e rx5day, particularmente na estação de inverno. As tendências opostas dos índices anuais cwd e cdd, que sugerem um aumento no número de dias com chuva, ao contrário, não foram bem detectadas pelo modelo RegCM3(s1). O aquecimento da temperatura mínima como conseqüência do aumento de noites quentes e diminuição de noites frias identificado em quase todo o continente foi simulado corretamente pelo modelo RegCM3(s2). Com relação à temperatura máxima, embora as observações não apresentem um padrão característico, a simulação do modelo RegCM3(s2) se mostra bastante semelhante ao apresentado pela reanálise do NCEP/NCAR. As distribuições espaciais de tendência dos índices anuais de temperatura e chuva resultantes das simulações do RegCM3(s2 e s1, respectivamente) e do HadAM3 sobre a América do Sul durante o período de 1961-1990 são bastante semelhantes entre si, embora o HadAM3 seja caracterizado por tendências mais suavizadas. Para os índices anuais e sazonais de temperatura, a simulação do HadAM3 se mostrou ligeiramente melhor à do RegCM3, enquanto que o inverso é encontrado para os índices anuais e sazonais de chuva. / The main goal of this study is to investigate if the RegCM3 model (Regional Climate Model version 3) is able to simulate the spatial patterns of some annual and seasonal climate indices of temperature and precipitation trend over South America for the present climate (1961-1990). The analysis is done for three different simulations where the model was running with different cumulus parametrization, i.e, Grell and Emanuel. An algorithm based on the software RClimDex was developed to calculate the indices. Different data sources such as the NCEP/NCAR reanalysis, individual observational stations and others were used to estimate the annual and seasonal indices of temperature and precipitation for the same region and period. Correlation and linear regression coefficients analysis were used in the results comparison. In general, the results suggest that the datasets can provide useful information about annual and seasonal indices of temperature and precipitation at individual grid cells in South America during the period 1961-1990. However, the NCEP/NCAR reanalysis showed reversal trend signals for some indices over Argentina. Within the three simulations with the RegCM3 model, the trends of the annual and seasonal indices of temperature and precipitation over South America are better reproduced by the Emanuel (s2) and Grell (s1) schemes, respectively. The RegCM3(s1) simulates the change to wetter conditions in South America through the r95p, prcptot and rx5day annual indices, particularly in the austral winter. On the other hand, the opposite signal of the trends in cdd and cwd indices, that indicates an increase in the number of days with precipitation, was not well represented by the model. The warming in minimum temperature as a consequence of the increase in the frequency of warm nights and the decrease of cold nights observed all over the South American continent was correctly simulated by the RegCM3(s2). Although the observed maximum temperature extremes did not show any special feature, the simulations with Grell scheme were able to represent the spatial patterns of the warm and cold days indices trend similar to the NCEP/NCAR reanalysis. The spatial distributions of the annual indices of temperature and precipitation trend obtained from the RegCM3(s2 and s1, respectively) and HadAM3 simulations over South America during the period 1961-1990 are very similar, though the HadAM3 shows a trend less intense. For the annual and seasonal indices of temperature, the HadAM3 simulation is slightly better than the RegCM3 running, while the opposite is found to the annual and seasonal indices of precipitation.