Published Article / The objective of this study was to characterize meteorological droughts in the Central Region of South Africa, Modder River Basin, C52A quaternary catchment using two popular drought indices: Standardized Precipitation Index (SPI) and Standardized Precipitation-Evapotranspiration Index (SPEI) and to compare the two indices. Drought events were characterized based on their frequency, duration, magnitude and intensity. The indices were computed for the time-scales that are important for planning and management of water resources, i.e. 3-, 6- and 12-month time-scales. The basic meteorological input data used in the computation of these indices were 57 years (1950-2007) of monthly precipitation and monthly temperature data which were recorded at The Cliff weather station in the quaternary catchment. It was found that both SPI and SPEI responded to drought events in similar fashion in all time-scales. During the analysis period, a total of 37, 26 and 17 drought events were identified in the area based on 3-, 6-, and 12-month times-scales, respectively. Considering event magnitude as severity parameter, results from both indices identified the periods 1984-1985, 1992-1993 and 2003-2005 as the severest drought periods in the area. However, when the effects of both drought duration and magnitude are considered (drought intensity), the most severest drought events were identified during the years 1982/83, 1966 and 1973 based on 3-, 6- and 12-month timescales, respectively. It was concluded that although the SPEI generally exhibits veracity over SPI by including, apart from precipitation, additional meteorological parameter, mean temperature, SPI should be adopted as an appropriate drought monitoring tool in an area, like Africa, where meteorological data are scarce.

The understanding of the dynamics of the climatic variables is critical to model and predict climatic and environmental changes. Traditional measures collected by the meteorological stations network are dispersedly located throughout the territory in the northern high latitudes and errors associated to these variations can be considerable. Our goal is to evaluate the contribution of the remote sensing by passive microwaves compared to the ground measurements for better characterizing the variations in the surface temperature during the winter. In the presence of snow, extraction of the surface parameters by microwave measurements is a complex and ill-conditioned problem. We evaluated a semi-empirical relation based on a theoretical analysis to estimate the surface temperatures with the measured brightness temperatures at 19 and 37 GHz (vertical polarization). Simulations of emissivity made with the Helsinki Technology University (HUT) model, the knowledge of the land cover, and the forest biomass enable us to define this relationship.The results of the comparison between the calculated surface temperatures and the air temperatures for the entire Canada (137 stations) and for two winters, 1992-93 and 2002-03 (16359 measurements) show a significant correlation with an estimation error ranging between 4 and 7[degrees Celsius] according to the regions considered. These results are discussed according to region and type of land cover (grassland, forest, tundra).

Lake surface water temperatures (LSWTs) of 246 globally distributed large lakes were derived from Along-Track Scanning Radiometers (ATSR) for the period 1991 to 2011. These LSWTs, derived in a systematic manner, presents an ideal opportunity to study LSWT behaviour on a global scale. In this thesis, the annual cycles of lake-mean LSWTs derived from these data quantify the responses of large lakes’ surface temperatures to the annual cycle of forcing by solar radiation and the ambient air temperature. Minimum monthly net surface solar irradiance (netSSI) strongly influences minimum LSWTs of non-seasonally ice covered lakes (where lake-mean LSWT remains above 1 ºC throughout the annual cycle), explaining > 0.88 (R2 adj) of the inter-lake variation in both hemispheres. In some regions, for seasonally ice covered lakes (where lake-mean LSWT remains below 1 ºC for part of the annual cycle) the minimum monthly netSSI is a better predictor than latitude, of the length of the frozen period, which shows the importance of local cloud climatological conditions. Additionally, at lake locations between 1º S to 12º N, the netSSI, shown to peak twice annually, is reflected in the LSWT annual cycle. The summer maximum LSWTs of lakes from 25º S to 35º N show a linear decrease with increasing altitude; -3.76 + 0.17 ºC km-1 (R2 adj = 0.95), marginally lower than the corresponding air temperature -4.15 + 0.24 ºC km-1 (R2 adj = 0.95) decrease with altitude. The start and end of the period where the lake-mean LSWT is greater than 4 ºC shows strong correlation with the spring and autumn 0 ºC air temperature crossing days, (R2 adj = 0.74 and 0.80 respectively). The temporally and spatially resolved LSWT observations allows for a greater practical understanding of LSWT behaviour of large lakes. For example, lakes with a greater LSWT annual range have more observed variability in the LSWT extremes, highlighting that they may be more responsive to changes in the climate than lakes with a low annual range. The nighttime LSWT trends show stronger warming than day-night trends in the all regions, except Europe. The lake centre LSWT trends and absolute values can be generally considered representative of the lake-mean LSWT trends and absolute values. The observed LSWT time series are used to tune a 1-dimensional thermodynamic lake model, FLake. By tuning FLake using only 3 basic lake properties, shown by myself to have the most influence over LSWTs (depth, snow and ice albedo and light extinction co-efficient), the daily mean absolute differences for 244 lakes is reduced from 3.38 + 2.74 ºC (untuned model) to 0.85 + 0.61 ºC (tuned model). The effect of wind speed, lake depth, albedo and light extinction co-efficient on LSWTs is demonstrated throughout the tuning process. The modelled summer LSWT response to changes in ice-off is strongly affected by lake depth and latitude explaining 0.50 (R2 adj, p = 0.001) of the inter-lake variation in summer LSWTs. Lake depth alone explains 0.35 (p = 0.003) of the variation, highlighting the sensitivity of the summer LSWTs of deeper lakes to changes in the ice-off. Statistically significant summer/ maximum month modelled LSWT trends, from 1979-2011 are presented for lakes where the modelled LSWTs are strongly supported by observed LSWTs over the period of available observed LSWTs. For these lakes, the trends show LSWT warming of between 0.73 – 2.10 ºC for 29 lakes in northern temperate regions over the 33 year period (1979 – 2011). The modelled regional trends of all lakes over the same period show least warming in Africa of 0.30 ºC and the greatest warming in Europe, 1.35 º.

Increased energy performance of the building stock of European Union is seen as an important measure towards mitigating climate change, increasing resource utilisation efficiency and energy supply security. Whether to improve the supply-side, the demand-side or both is an open issue. This conflict is even more apparent in countries such as Sweden with a high penetration of district heating (DH). Many Swedish DH systems have high share of secondary energy resources such as forest industry residuals, waste material incineration and waste heat; and resource efficient cogeneration of electricity in combined heat and power (CHP) plants. When implementing an energy conservation measure (ECM) in a DH connected building stock, it will affect the operation of the whole DH system. If there are CHP plants and the cogeneration of electricity decreases due to an ECM, and this electricity is valued higher than the fuel savings, the consequences of the ECM would be negative.  These complex relationships are investigated by conducting a case study on the Eskilstuna DH system, a renewable energy supply system with relatively high share of cogenerated electricity. Heat demand profiles of ECMs are determined by building energy simulation, using recently deep energy retrofitted multifamily buildings of the “Million Programme”-era in Eskilstuna as model basis. How implementing ECMs impact on the DH system’s heat and electricity production under different electricity revenue scenarios has been computed and evaluated in terms of resource efficiency and CO2 emissions.  The results show that different ECMs in the buildings impact differently on the DH system. Measures such as improved insulation level of the building’s envelope, that decrease the heat demand’s dependence to outdoor temperature, increase the amount of cogenerated electricity. While measures such as thermal solar panels, which save heat during summer, affects the absolute amount of cogenerated electricity negatively. Revenues from cogenerated electricity influence the amount of cost-effectively produced electricity much more than the impact from ECMs. Environmental benefits of the ECMs, measured in CO2 emissions and primary energy consumption, are quite small in DH systems that have high share of forest residual fuels and electricity cogeneration. The consequences can even be negative if ECMs lead to increased need of imported electricity that is produced resource inefficiently or/and by fossil fuels. However, all studied ECMs increase the relative amount of cogenerated electricity, the ratio between amount of cogenerated electricity and the heat load. This implied that all ECMs increase the overall efficiency of the Eskilstuna DH system.

An incoherent CO₂ laser radar, or lidar, system using a tunable CO₂ TEA laser has been developed, along with analytical techniques to permit the determination of atmospheric transmittance and aerosol backscatter from multi-angle lidar returns. This work has been motivated by the need for a more complete knowledge of the optical properties of the atmosphere in the 9 to 11 μm spectral region. Results of preliminary observations are discussed. CO₂ lidar systems have been used before to measure backscatter and transmittance. Here, a new analytic method is developed, applicable to the 8-12 μm window region in conditions of high visibility, when the aerosol component of extinction is negligible compared to the molecular component. In such cases the backscatter sensed by the system is due to the atmospheric aerosol while atmospheric transmittance is determined by molecular species such as carbon dioxide and water vapor. It is not possible to assume a functional relationship between backscatter and extinction, as required by many previous analytic techniques. Therefore, a new solution technique based on a weighted, non-linear least squares fit applied to multi-zenith angle lidar returns has been developed. It is shown how constraints may be applied to rule out solutions which are unlikely on a priori grounds. An error analysis and a discussion of proper weighting techniques are presented. A CO₂ lidar system capable of acquiring multi-angle returns was developed, which included a gain-switching amplifier to compress the dynamic range of the return signal. The entire system is operated under computer control and data acquisition and storage are fully automated. A laser pulse energy monitor allows sequential returns to be averaged to reduce signal fluctuations. Preliminary observations with the system have demonstrated the capability of acquiring and averaging hundreds of returns on a routine basis. The return signal was observed to have fluctuations of 20 to 50% from shot to shot, due to atmospheric fluctuations. This result indicates signal averaging will be necessary to reduce signal fluctuations to levels where the multi-angle solution method may be applied.

Baigiamajame magistro darbe nagrinėjama trumpalaikė ozono koncentracijos kaita ir jos priklausomybė nuo meteorologinių parametrų. Literatūros apžvalgoje aptariama ozono susidarymas, cheminės savybės, poveikis žmogaus sveikatai ir augalams. Atlikta 2000-2009 metais Preilos monitoringo stotyje gautų duomenų (vienos valandos vidurkiai) analizė. 2009 metų šiltuoju sezonu atliktas eksperimentas, sudaryta dešimties ir dviejų minučių vidurkių ozono koncentracijos ir meteorologinių parametrų duomenų bazė. Parametrų tarpusavio priklausomybė nustatyta panaudojant tiesinės regresijos metodą, apskaičiuoti koreliacijos koeficientai. Pasinaudojant Furje metodu atlikta ozono bei meteorologinių parametrų spektrinė analizė. Buvo rasti pagrindiniai dažnių pikai, kurie labiausiai išryškėja. Darbą sudaro 6 dalys: įvadas, literatūros apžvalga, matavimo prietaisai ir metodika, eksperimentinių tyrimų rezultatai, išvados ir literatūros sąrašas. Darbo apimtis – 57 p. teksto be priedų, 38 paveikslai., 3 lentelės, 53 bibliografiniai šaltiniai. Atskirai pridedami darbo priedai. / In master final work the variation of short-term ozone concentration variations were analyzed. Ozone formation, chemical characteristics, impact on human health and plants were described. The study of the short- and long-term ozone concentration variations dependence on meteorological parameters is presented. The data of hourly parameters obtained at the monitoring station Preila during 2000-2009 years were analyzed. The 2 and 10 minutes average values of the ozone concentration and meteorological parameters were collected during experiment in warm season of 2009 year. The regression analysis was applied for the determination of the correlation coefficients between variables. The strongest relationship from the long-term variations was found between ozone concentration and temperature. The strongest relationship from the short-term variations was found between ozone concentration and wind speed. Structure: introduction, literary review, measurements instruments and methodology, experimental research results, conclusions and references. Thesis consists of: 57 p. text without appendixes, 38 pictures, 3 tables, 53 bibliographical entries. Appendixes included.

The Asian summer monsoon (ASM) is a high-dimensional and highly complex phenomenon affecting more than one fifth of the world population. The intraseasonal component of the ASM undergoes periods of active and break phases associated respectively with enhanced and reduced rainfall over the Indian subcontinent and surroundings. In this thesis the nonlinear nature of the intraseasonal monsoon variability is investigated using the leading Empirical Orthogonal Functions of ERA-40 sea level pressure reanalyses field over the ASM region. The probability density function is then computed in spherical coordinates using the Epaneshnikov kernel method. Three significant modes are identified. They represent respectively (i) the East - West mode with above normal sea level pressure over East China sea and below normal pressure over Himalayas, (ii) the mode with above normal sea level pressure over East China sea (without compensating centre of opposite sign as in (i)) and (iii) the mode with below normal sea level pressure over East China sea (same as (ii) but with opposite sign). The relationship with large-scale forcing is also investigated by stratifying the PCs according to representing indices. The regimes derived from spherical PDFs appear to be opposite under opposite large-scale conditions. EOF technique with...

Sea state is a subjective quantity whose accuracy depends on an observer’s ability to translate local wind waves into numerical scales. It provides an analytical tool for estimating the impact of the sea on data quality and operational safety. Tasks dependent on the characteristics of local sea surface conditions often require accurate and immediate assessment. An attempt to automate sea state classification using eleven years of ship motion and sea state observation data is made using parametric modeling of distribution-based confidence and tolerance intervals and a probabilistic model using sea state frequencies. Models utilizing distribution intervals are not able to exactly convert ship motion data into various sea states scales with significant accuracy. Model averages compared to sea state tolerances do provide improved statistical accuracy but the results are limited to trend assessment. The probabilistic model provides better prediction potential than interval-based models, but is spatially and temporally dependent.

A thesis submitted to the faculty of science, at the University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2017. / Water resource monitoring plays a pivotal role in a number of sectors such as determining sustainable abstraction and use of water, determining the feasibility of development projects in relation to water, and developing systematic strategies for efficient overall management of the water resources. It has been observed by a number of scholars and policy makers that through periodic monitoring of water resources, valuable data can be collected which can then provide information sufficient to determine trends and develop predictive models. It is only when sound and reliable data is available that informed decisions about sustainable and efficient use of water resources can be made. Despite the importance of water resource monitoring, many countries in Sub-Saharan Africa, particularly in South Africa, are not effectively and adequately monitoring the quantity and quality of water resources. Part of the reason for this state of affairs has been the absence of clearly defined roles, policies, strategies and responsibilities and a combination of these factors have resulted in significant fragmentations in the institutional structures mandated to manage water resources. Using expert sampling, interviews with key informants and other purposively chosen participants, revealed the challenges in the changing political landscape of South African water resource monitoring many of which were further reiterated in the focus group discussions. The identified challenges served as entry points that would improve water resources monitoring and enable decision makers to make sustainable management decisions. It is suggested that water resource monitoring programmes could be used as a tool for sustainable water resource monitoring in South Africa. However, climate change and urbanization bring about a certain level of complexity, uncertainty and conflict as the water landscape of water resources changes continuously. The impact of the above phenomena cannot be measured as current monitoring systems are not functioning optimally. Furthermore, monitoring programmes are not being used to their full potential due to governance challenges. This is due to conflicting roles that the Department of Water and Sanitation (DWS) plays in the water sector i.e. policy developer, supporter and regulator, which in turn confound the roles and responsibilities of its employees. Moreover, it was found that five major challenges impede the formation of a comprehensive water resources management system namely; lack of financial resources, lack of skilled human resources, poor governance structure, ineffective stakeholder engagement – ‘working in silos’ and inefficient data management. More importantly, it was found that sustainability of monitoring programmes relies on human and economic investment. The main recommendations made include institutional reform and enabling legislation which form the basis upon which any development efforts can be pursued to achieve sustainable water resource monitoring. In addition, capacity building and strengthening is recommended as another way to help build sustainable resource management institutions which include skills and institutional memory transfer from the experienced players to the younger and newer employees. The creation and/or optimization of water resource monitoring databases is one of the viable ways for sustainable water resource management to be realized. Furthermore, research can be conducted to assess the challenges in water resource monitoring and provide sustainable solutions; with the aim of quantifying the impact of policy reforms in the water sector. And finally, research can be done on how effective regulation and co-operative governance for water sector can be achieved in South Africa through participatory processes that are aimed at developing priority water research questions. Keywords: water resource monitoring, institutional framework, integrated water resource management, water governance. / GR2018

A utilização de secadores de produtos agrícolas é oportuna às necessidades do pequeno produtor rural, pois o produto desidratado possui maior valor agregado em relação ao mesmo produto fresco, requer menor espaço de armazenamento e tem maior durabilidade. É necessário, no entanto, oferecer ao produtor familiar equipamentos economicamente viáveis e, se possível, que utilizem recursos naturais e renováveis como fonte de energia, aliando sustentabilidade e crescimento econômico. Diante disso, os objetivos foram estudar o comportamento da temperatura e da umidade relativa do ar no interior de um secador solar misto de ventilação natural em função das condições meteorológicas externas, e os períodos e épocas do ano mais ou menos favoráveis ao processo de secagem, em função da combinação das variáveis meteorológicas. Pode-se concluir que nem sempre elevados valores de radiação resultam em elevados valores de temperatura dentro do secador. Dias nublados e, principalmente chuvosos, comprometem mais o desempenho do secador do que, por exemplo, as perdas térmicas decorrentes da velocidade do vento que o circunda. O secador cumpre o papel de manter sua temperatura maior que a temperatura externa, predominantemente, entre 06h e 18h, enquanto que no restante do dia o comportamento da temperatura e da umidade relativa, dentro e fora do equipamento, assemelha-se. Períodos com elevada incidência solar e pouca chuva são os mais favoráveis à secagem. No entanto, é possível que meses de inverno e de pouca chuva tenham melhor desempenho do que meses situados ou próximos do verão que possuam dias nublados e chuvosos constantemente. / The use of dryers to dehydrate agricultural products is appropriate to the needs of small farmers, because the dehydrated product has higher added value compared to the fresh ones, requires less storage space and lasts longer. It is necessary, however, offer to the small farmer economically viable equipment and, if possible, using natural and renewable energy sources , combining sustainability and economic growth. Therefore, the objectives were to study the behaviour of temperature and relative humidity inside a mixed-mode solar dryer with natural ventilation due to external weather conditions. And also the periods more or less favorable to the drying process, depending on the combination of meteorological variables. It was concluded that not always higher solar radiation results in higher temperature values inside the dryer. Cloudy and mainly rainy days may disturb the performance of the dryer, more than, for example, thermal losses due to the wind speed surrounding it. The data showed also that It was possible for the dryer to maintain its temperature higher than the outside temperature, predominantly between 06h and 18 h, while in the rest of the day the behaviour of temperature and relative humidity inside and outside of the equipment, resembles. Periods of high sunlight intensity and little rain are the most favorable to drying. However, winter months with little rain may present better performance than months situated near or in the summer but having cloudy and rain constantly.