Thesis (MScAgric (Horticulture))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Creasing, also known as albedo breakdown, is a preharvest disorder that affects the albedo of citrus fruit causing creases on the surface of the fruit. It is a recurrent problem in Navel and Valencia oranges and can cause individual orchard losses which often exceed 50%. Although the contributing factors are known, the physiological basis of creasing development is unresolved and the current control measures do not prevent creasing satisfactory. Hence, better control measures and further understanding of the physiology of creasing development is required. The objective of this two-year study was to determine if the position of fruit in a tree, light and carbohydrate manipulation techniques, and albedo mineral nutrients influence creasing development. Furthermore, the most effective application timing of gibberellic acid (GA3) with the least negative effect on fruit rind colour development and the effectiveness of cytokinins, other products and different root biostimulants to reduce creasing incidence were evaluated. The position of fruit in the tree and light influenced the development of creasing and the distribution of mineral nutrients in the albedo. Creasing incidence was higher on the south side than on the north side of the tree and fruit from the inside sub-sectors had a greater creasing incidence compared to fruit from the outside sub-sectors. The shady part of outside fruit was more creased compared to the sunny part of the fruit and covering fruit with brown paper bags increased creasing severity. The light manipulation techniques used on the leaves and fruit increased the nitrogen (N), phosphorus (P), potassium (K) and manganese (Mn) concentrations in the albedo and differences in the albedo mineral nutrients amongst the sub-sectors evaluated were observed, but creasing severity or creasing incidence was not significantly correlated with the albedo mineral concentrations at harvest. Albedo mineral concentrations earlier in the season may play a role in creasing development, as creasing severity was significantly correlated with copper (Cu), K, and Mn concentrations in the albedo during stage II of fruit development. Creasing incidence and albedo mineral concentrations were not affected by any of the carbohydrate manipulation techniques used in this study. The incidence and severity of creasing was significantly reduced, with a minor negative effect on fruit rind colour development, by the application of GA3, from mid November to mid January. Localised fruit application of CPPU [N-(2-chloro-4-pyridyl)-N-phenylurea], MaxCel (6- Benzyladenine) and CPPU in combination with calcium after physiological fruit drop reduced the incidence and severity of creasing, although creasing incidence was not significantly different from the control. The application of Messenger®, AVG (aminoethoxyvinylglycine) and different root biostimulants did not reduce creasing incidence. The results showed that cytokinins could reduce creasing incidence and justify further studies on application and uptake efficiency. The use of different root biostimulants are not recommended, but it is suggested that treatment effects may be more pronounced over a longer period. / AFRIKAANSE OPSOMMING: Kraakskil is ‘n vooroes abnormalitiet wat die albedo van sitrusvrugte affekteer, deur krake op die oppervlak van vrugte te veroorsaak. Dit is ‘n algemene probleem in Navel en Valencia lemoene en kan boordverliese van tot 50% of soms hoër veroorsaak. Alhoewel die bydraende faktore bekend is, is die fisiologiese basis van kraakskil ontwikkeling onopgelos en die beskikbare beheermaatreëls is nie bevredigend nie. Dus, beter beheermaatreëls en ‘n beter begrip van die fisiologie van kraakskil ontwikkeling is nodig. Die doel van die twee-jaar studie was om te bepaal of die posisie van vrugte in ‘n boom, lig en koolhidraat manipulasie tegnieke en minerale elemente in die albedo, kraakskil ontwikkeling beïnvloed. Die mees effektiewe toedieningstyd van gibberelliensuur (GA3) sonder ‘n negatiewe effek op vrugkleur is bepaal en die effektiwiteit van sitokiniene, ander produkte en verskillende wortel biostimulante om kraakskil voorkoms te verminder, is geëvalueer. Die posisie van vrugte in ‘n boom en lig het kraakskil ontwikkeling en die verspreiding van minerale element in die albedo beïnvloed. Kraakskil voorkoms was hoër aan die suidekant van die boom as aan die noordekant en vrugte in die binnekant van die boom het ‘n groter kraakskil voorkoms as vrugte in die buitekant van die boom gehad. Die skadukant van buitevrugte het meer kraakskil gehad as die sonkant en die toemaak van vrugte met ‘n bruin papiersak het die graad van kraaksil verhoog. Die lig manipulasie tegnieke wat op die blare en vrugte gebruik is, het die stikstof (N), fosfaat (P), kalium (K) en mangaan (Mn) konsentasies in die albedo verhoog en verskille in die albedo minerale elemente tussen sub-sektore is waargeneem, maar betekenisvolle korrelasies is nie tussen die graad en voorkoms van kraakskil en die albedo minerale element konsentrasies by oestyd waargeneem nie. Albedo minerale element konsentrasies vroeër in die seisoen mag ‘n rol speel by kraakskil ontwikkeling, omdat die graad van kraakskil betekenisvol gekorreleer was met albedo koper (Cu), K, en Mn konsentrasies tydens fase II van vrugontwikkeling. Kraakskil voorkoms en albedo minerale element konsentrasies is nie deur enige van die koolhidraat manipulasie tegnieke geaffekteer nie. Die voorkoms en graad van kraakskil is betekenisvol verlaag, met ‘n geringe negatiewe effek op vrugkleur, deur die toediening van GA3 vanaf mid November tot mid Januarie. Gelokaliseerde vrugtoedienings van CPPU [N-(2-chloro-4-piridiel)-N-phenielureum], MaxCel (6- Bensieladenien) en CPPU saam met kalsium na fisiologiese vrugval het die voorkoms en graad van kraakskil verlaag, alhoewel kraakskil voorkoms nie betekenisvol van die kontrole verskil het nie. Die toediening van Messenger®, AVG (amino etoksievinielglisien) en veskillende wortel biostimulante het nie kraakskil voorkoms verlaag nie. Die resultate het getoon dat sitokiniene kraakskil voorkoms kan verlaag en verdere studies op die toediening en opname effektiwiteit word aanbeveel. Die gebruik van verskillende wortel biostimulante word nie aanbeveel nie, maar die effek behoort meer sigbaar te wees na ‘n langer periode van behandeling.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-05-08T20:34:41Z No. of bitstreams: 1 ELAINE CRISTINA OLIVEIRA DA SILVA – DISSERTAÇÃO (PPGEG) 2017.pdf: 1517360 bytes, checksum: 56e4b4359a04442e312735ed832f977d (MD5) / Made available in DSpace on 2018-05-08T20:34:41Z (GMT). No. of bitstreams: 1 ELAINE CRISTINA OLIVEIRA DA SILVA – DISSERTAÇÃO (PPGEG) 2017.pdf: 1517360 bytes, checksum: 56e4b4359a04442e312735ed832f977d (MD5) Previous issue date: 2017-03-02 / O maracujá é uma fruta abundante no Brasil, considerado o maior produtor do mundo. Cerca de 52% do peso total do fruto são compostos por casca (albedo e flavedo), que pode ser utilizada na fabricação de farinha como fonte de nutrientes para a alimentação e enriquecimento de produtos alimentícios. Alguns estudiosos removem o flavedo e acrescentam, na elaboração da farinha, a etapa de maceração em água pois afirmam que a mesma possui uma substância responsável, por causar amargor. Assim, o objetivo do presente trabalho foi estudar o processo de fabricação de farinha do albedo e da casca integral de maracujá amarelo (Passiflora edulis f. Flavocarpa), verificando as influências das etapas de remoção do flavedo e de maceração, assim como a variação das temperaturas de secagem na composição final da farinha. Após o processo de maceração as amostras foram trituradas e submetidas à secagem convectiva em estufa nas temperaturas de 70 e 80 °C. Foi calculado o rendimento após as secagens e se notou que o mesmo é muito baixo. Os modelos matemáticos de Page, Silva et alii, Henderson e Pabis e Logaritmo, foram ajustados aos dados experimentais utilizando-se o software LAB Fit. Os critérios de avaliação utilizados para identificar o melhor ajuste dos modelos aos dados experimentais foram o coeficiente de determinação (R2) e o quiquadrado (χ2). O modelo de Page foi o que melhor se ajustou aos dados, apresentando R² maior que 0,99 em todas as amostras, além de χ2 almejados, sendo o maior de 0,019287. As matérias-primas foram analisadas quanto ao teor de umidade, cinzas, atividade de água e cor (L*, a* e b*). Na análise das farinhas elaboradas ainda foram acrescentados proteínas, lipídios, carboidratos, pectina, fibra bruta, FDN, FDA e minerais. Em todas as análises foi aplicado o teste de Tukey (p < 0,05). Com relação às análises realizadas com as farinhas, a atividade de água mostrou que as cascas maceradas são menos susceptíveis ao desenvolvimento de reações provenientes do teor de umidade. A cor mostrou-se clara, com leve disposição à tonalidade vermelha e tendência maior à coloração amarela. O teor de umidade se encontra dentro dos limites estabelecidos pela ANVISA. No que diz respeito às cinzas, observou-se que a maceração contribuiu para sua redução. Com relação aos lipídios, foi verificado que todas as farinhas possuem valor abaixo de 1,0%. Os carboidratos foram mais elevados nas amostras sem maceração e secas a 70 °C. A maceração e o aumento de temperatura contribuíram para a redução das proteínas e o aumento da fibra bruta. Os valores de FDN e FDA foram maiores nas amostras de albedo macerado. O valor de pectina foi muito baixo em todas as farinhas. Os minerais encontrados foram, na ordem de abundância: potássio, cloro, cálcio, fósforo, enxofre, ferro, estrôncio, rubídio, zinco, bromo, manganês, cobre e zircônio. Recomenda-se a fabricação da farinha com a casca integral sem a maceração e seca a 70 °C. / Passion fruit is an abundant fruit in Brazil, considered as the largest producer in the world. Approximately 52% of the total fruit weight is composed of skin (albedo and flavedo), which can be used to manufacture flour as source of nutrients for consumption and enrichment of food products. Some researchers remove the flavedo and add, in the manufacturing of flour, the step of maceration in water, because they claim it has a substance responsible for causing bitterness. Thus, this study aimed to evaluate the process of manufacturing flour from the albedo and whole skin of yellow passion fruit (Passiflora edulis f. Flavicarpa), verifying the influences of the flavedo removal and maceration steps, as well as the variation of the drying temperatures in the final composition of the flour. After maceration, the samples were ground and subjected to convective drying in an oven at temperatures of 70 and 80 °C. The yield after the drying processes was calculated and were found to be very low. The mathematical models of Page, Silva et alii, Henderson & Pabis and Logarithmic were fitted to the experimental data using the software LAB Fit. The evaluation criteria to identify the best fit of the models to the experimental data were the coefficient of determination (R 2) and chisquare (χ2). The model of Page showed the best fit to the data, with R² higher than 0.99 in all samples, and the desired χ2, whose highest value was 0.019287. The raw materials were analyzed for moisture content, ashes, water activity and color (L*, a* and b*). The manufactured flours were also analyzed for proteins, lipids, carbohydrates, pectin, crude fiber, NDF, ADF and minerals. Tukey test (p < 0.05) was applied in all analyses. For flour analyses, the water activity demonstrated that the macerated skins are less susceptible to the development of reactions from the moisture content. The color was light, with slight trend to red and greater trend to yellow. The moisture content is within the limits established by ANVISA. The maceration contributed to the reduction of ashes. For lipids, all flours exhibited values below 1.0%. Carbohydrates were higher in samples without maceration and dried at 70 ºC. The maceration and increase in temperature contributed to the reduction of proteins and increase in crude fiber. NDF and ADF contents were higher in the samples of macerated albedo. The pectin content was very low in all flours. The minerals found, in order of abundance, were: potassium, chlorine, calcium, phosphorus, sulfur, iron, strontium, rubidium, zinc, bromine, manganese, copper and zirconium. The flour should be manufactured using the whole skin, without maceration and dried at 70 ºC.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-10-04T23:59:19Z No. of bitstreams: 1 JeaneGaldinoFaustinoLima_DISSERT.pdf: 1417447 bytes, checksum: 45a8559a124d8412550202f77b1f9a42 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-10-16T20:53:48Z (GMT) No. of bitstreams: 1 JeaneGaldinoFaustinoLima_DISSERT.pdf: 1417447 bytes, checksum: 45a8559a124d8412550202f77b1f9a42 (MD5) / Made available in DSpace on 2017-10-16T20:53:48Z (GMT). No. of bitstreams: 1 JeaneGaldinoFaustinoLima_DISSERT.pdf: 1417447 bytes, checksum: 45a8559a124d8412550202f77b1f9a42 (MD5) Previous issue date: 2017-05-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A mudan?a na cobertura do solo provoca altera??es no balan?o de energia e no balan?o h?drico ? superf?cie. O uso inadequado do solo pode levar a uma condi??o de degrada??o avan?ada, a qual ? denominada de processo de desertifica??o. No Brasil, existem v?rios N?cleos de Desertifica??o, dentre os quais o N?cleo de Desertifica??o do Serid? (RN-PB). Assim, o presente trabalho partiu da premissa de que o processo de desertifica??o na regi?o do Serid? Potiguar (RN), possivelmente, tem causado variabilidades na temperatura da superf?cie, no albedo e nos fluxos de energia e massa (evapotranspira??o/fra??o evaporativa). Para comprovar as mudan?as decorrentes deste processo foi realizada uma an?lise descritiva/comparativa entre dados de ?rea degradada e ?rea com Caatinga preservada (Esta??o Ecol?gica do Serid?-ESEC). Para tanto, utilizou-se de um algoritmo h?brido, o qual ? composto de parametriza??es de v?rios algoritmos tais como: o Surface Energy Balance Algorithms for Land/SEBAL, Simplified Surface Energy Balance/SSEB, Simplified Energy Balance Index/S-SEBI, e de imagens TM ? Landsat 5, das ?rbitas-ponto: 215/65, adquiridas gratuitamente junto ao INPE ? Instituto Nacional de Pesquisas Espaciais ? sob a condi??o de c?u claro, para datas dos anos de 1990, 1995, 1998, 1999, 2001, 2003, 2005, 2007. Comparando os resultados obtidos em ?rea degradada e vegetada, foi observado a exist?ncia de diferen?as entre os valores m?dios do albedo, saldo de radia??o e fra??o evaporativa. Esta diferen?a tamb?m foi comprovada de forma significativa por meio de teste estat?stico (teste t de student), o que corrobora a hip?tese de que o processo de desertifica??o derivado do mau uso do solo e das condi??es clim?ticas da regi?o est? causando altera??es nas vari?veis constituintes do balan?o de energia. / The change in soil cover causes changes in the energy balance and surface water balance. Inadequate soil use can lead to an advanced degradation condition, which is called a desertification process. In Brazil, there are several Desertification Nuclei, among which the Serid? Desertification Nucleus (RN-PB). Thus, the present work started from the premise that the desertification process in the Serid? Potiguar (RN) region has possibly caused variability in surface temperature, albedo, and energy and mass fluxes (evapotranspiration / evaporative fraction). To verify the changes resulting from this process, a descriptive / comparative analysis was carried out between degraded area data and preserved Caatinga area (Serid?-ESEC Ecological Station). For this, a hybrid algorithm was used, which is composed of parametrizations of several algorithms such as: Surface Energy Balance Algorithms for Land / SEBAL, Simplified Surface Energy Balance / SSEB, and S-SEBI, and Of images - Landsat 5, of orbits-point: 215/65, acquired free of charge from INPE - National Space Research Institute - under the condition of clear sky, for dates of 1990, 1995, 1998, 1999, 2001, 2003, 2005, 2007. Comparing the results obtained in degraded and vegetated areas, it was observed the existence of differences between the average values of albedo, radiation balance and evaporative fraction. This difference was also significantly demonstrated by means of a statistical test (student's t test), which corroborates the hypothesis that the desertification process derived from the misuse of the soil and the climatic conditions of the region is causing changes in the constituent variables of the Energy balance.

O principal objetivo deste estudo foi avaliar a refletância e sua influência no comportamento térmico de tintas refletivas e tintas convencionais aplicadas em telhas de fibrocimento para cobertura de habitações brasileiras. Foram realizados ensaios em laboratório de determinação de cor e de brilho por medida instrumental e determinação da refletância por análise espectrofotométrica em películas. Para o estudo do comportamento térmico foram realizados ensaios de simulação em laboratório com corpos-de-prova expostos à radiação infravermelha emitida por lâmpadas e de exposição à radiação solar em campo através de protótipos com monitorização da temperatura durante as exposições. Os resultados dos ensaios de determinação de cor e de brilho mostraram que as pinturas refletivas e convencionais realmente apresentaram cores correspondentes. Os resultados de refletância mostraram que as pinturas refletivas apresentaram valores de refletância superiores em relação às tintas convencionais, o que foi comprovado pela temperatura medida nos ensaios de exposição à radiação infravermelha e radiação solar. A conclusão do estudo é que as tintas refletivas têm potencial para redução da temperatura superficial da telha de fibrocimento e que é necessária uma continuidade do estudo de durabilidade e do desempenho térmico de tintas refletivas coloridas. / The main purpose of this study was to investigate the effect of reflective colored paints and conventional colored paints applied on fiber cement corrugated roofing sheets, proving whether both type of paints can present different reflection characteristics in the infrared solar radiation and high thermal performance. Color and gloss were measured by instrumental methods and reflectivity (reflection coefficient) was measured using spectrophotometers equipped with integrating spheres in free paint films. In order to investigate the thermal performance of reflective and conventional paints, simulation tests were performed in laboratory by IR lamps using fiber cement specimens and in field by exposure solar radiation using prototypes with temperature monitoring. The results showed that the reflective paints present higher reflectivity and better thermal performance than the conventional paint, independently of the color. The results showed that the reflective paints present potential to reduce superficial temperature of fiber cement corrugated roofing sheets. It is necessary to continue the reflective colored paints study on durability and thermal performance by exposure tests.

Submitted by (lucia.rodrigues@ufrpe.br) on 2016-10-18T12:47:21Z No. of bitstreams: 1 Taciana Oliveira dos Santos.pdf: 6392936 bytes, checksum: c3276b7eadcc0a19441877f4f21521af (MD5) / Made available in DSpace on 2016-10-18T12:47:21Z (GMT). No. of bitstreams: 1 Taciana Oliveira dos Santos.pdf: 6392936 bytes, checksum: c3276b7eadcc0a19441877f4f21521af (MD5) Previous issue date: 2011-09-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The phenomenon of urban heat islands is directly related to human activities and the type of materials and equipment used in the expansion of the urban fabric (concrete, asphalt, roofing, etc..), Which absorb and retain heat from sunlight, mainly because it is not just used to process Evaporative which certainly feeds the increase in air temperature in cities. Thus, this study was to analyze and identify the phenomenon of urban heat island between urban areas of Recife-PE, from TM images Landsat 5. For the study was obtained images from orbit 214 points 65 and 66, the dates of 04/08/1998 and 06/09/2010. From the image processing were generated letters of the surface temperature, albedo and NDVI to the city of Recife and five selected districts (Pina Santo Amaro, Casa Amarela, Dois irmãos and Curado ), to analyze the dynamics of transformation occurring in area study. Through the profile developed for the study area was perceived to increase spatial and temporal surface temperature toward the center-suburbs, resulting in a difference of 6°C between these areas. Neighborhoods with urban concentrations, lots of buildings vertical and horizontal, stood out as those at higher temperatures, performing over 27°C, found in the districts of Casa Amarela and the Santo Amaro. In areas where there was a reduction of the vegetation index was an increase in surface temperatures around 3°C. The emergence heat islands can be attributed to following factors: concentration buildings which implies in increased temperature; energy production anthropogenic issuing heat coming industries, transits and dwellings; replacement vegetation by asphalt; radiation, caused by emissivity bodies. / O fenômeno ilhas de calor urbano está diretamente relacionado com as atividades humanas e com o tipo de materiais e equipamentos empregados na expansão da malha urbana (concreto, asfaltos, telhados, etc.), os quais absorvem e conservam o calor proveniente da radiação solar, principalmente por não ser praticamente utilizado no processo evaporativo o que certamente alimenta o aumento da temperatura do ar nas cidades. Assim, este trabalho foi conduzido com objetivo analisar e identificar o fenômeno ilha de calor entre áreas urbanas da cidade do Recife-PE, a partir de imagens TM do satélite Landsat 5. Para a realização do estudo foram obtidas imagens da órbita 214 dos pontos 65 e 66, nas datas de 04/08/1998 e 06/09/2010. A partir do processamento das imagens foram geradas cartas de temperatura da superfície, albedo e NDVI para a cidade do Recife e cinco bairros selecionados (Pina, Santo Amaro, Casa Amarela, Dois Irmão e Curado), para analisar a dinâmica de transformação ocorrida na região de estudo. Por meio do perfil desenvolvido para área de estudo foi perceptível o aumento espacial e temporal das temperaturas da superfície no sentido centro-subúrbio, resultando em uma diferença de 6°C entre essas áreas. Os bairros com adensamento urbano, grande quantidade de construções verticais e horizontais, destacaram-se como os que possuem temperaturas mais elevadas, apresentando-se acima de 27°C, constatado nos bairros de Casa Amarela e Santo Amaro. Nas áreas onde ocorreu redução do índice de vegetação houve um aumento da temperatura da superfície em torno de 3°C. O surgimento das ilhas de calor pode ser atribuído aos seguintes fatores: concentração de edificações, que implica no acréscimo da temperatura; produção de energia antropogênica pela emissão de calor provenientes das indústrias, trânsitos e habitações; substituição da cobertura vegetal pelo asfalto; a radiação, causada pela emissividade de corpos.

Nous nous intéressons à l'estimation de la distribution spectrale de l'éclairement solaire au sol en tout lieu et tout instant. Etant donné le très petit nombre de stations de mesure au sol, nous nous proposons de développer une méthode numérique exploitant des estimations de la composition atmosphérique faites quotidiennement. Cette méthode doit être suffisamment rapide pour être utilisée en mode intensif de manière opérationnelle. Les domaines d'applications ciblés sont l'ultraviolet (UV), la photosynthèse et la lumière du jour, avec une limitation au cas du ciel clair. Notre première innovation est de partir paradoxalement des approches numériques très rapides et précises de calcul de l'éclairement total. Ces approches développées donnent une description de la distribution spectrale du rayonnement solaire en un nombre restreint de bandes discrètes. La plus fine et la plus récente de ces approches est la «k distribution method and the correlated k approximation» de Kato et al. (1999). Elle fournit des estimations de l'éclairement dans 32 bandes spectrales. Pour atteindre l'objectif de la thèse, nous avons tout d'abord étudié la précision de cette approche dans chacune des 32 bandes. Les résultats sont bons dans toutes les bandes excepté l'UV. Nous avons proposé une nouvelle paramétrisation de la transmittance de l'ozone, que nous avons intégré au code numérique de transfert radiatif libRadtran. Enfin, nous avons élaboré deux techniques de ré-échantillonnage permettant d'obtenir à partir des 32 valeurs discrètes, des estimations de l'éclairement dans n'importe quel intervalle spectral, y compris en prenant en compte une réponse spectrale du système éclairé. Des validations ont pu être faites à l'aide de quelques stations de mesures. Les premiers résultats sont jugés encourageants en comparaison avec la précision relevée sur les instruments de mesure de qualité. Des voies d'améliorations ont pu être recensées pour un gain de précision notable. / We are interested in the estimation of the spectral distribution of the solar irradiance on the ground in any place and time. Given the very small number of measurement stations on the ground, we suggest developing a digital method exploiting estimations of the atmospheric composition made daily. This method must be enough fast to be used in intensive mode in an operational way. The targeted fields of application are the ultraviolet (UV), photosynthesis and daylight; with a limitation in the case of the clear sky. Our first innovation is to leave paradoxically from very rapid numerical approaches of calculation of the total irradiance. These developed approaches give a description of the spectral distribution of solar irradiance in a number restricted by discrete bands. The finest and the most recent of these approaches is «k-distribution method and the correlated-k approximation» of Kato and al. (1999). It supplies estimations of the irradiance in 32 spectral bands. To achieve this PhD goal, we have first of all, studied the accuracy of the approach in each of 32 bands. The results are good in all the bands except in the UV. We proposed a novel parametrization of the transmittance of the ozone, which we integrated into the radiative transfer model libRadtran. Finally, we developed two techniques of re-sampling allowing to obtain from 32 discrete values, estimations of the irradiance in any spectral interval, including by taking into account a spectral response of the illuminated system. Experimental validations have been carried out by means of some measurement stations. The preliminary results are considered encouraging in comparison with the precision found on quality measuring instruments. Ways of improvements have been listed for a gain of notable precision.

Despite large efforts and decades of research, the scientific understanding of how aerosols impact climate by modulating microphysical cloud properties is still low and associated radiative forcing estimates (RFaci ) vary with a wide spread. But since anthropogenically forced aerosol-cloud interactions (ACI) are considered to oppose parts of the global warming, it is crucial to know their contribution to the total radiative forcing in order to improve climate predictions. To obtain a better understanding and quantification of ACI and the associated radiative effect it as been suggested to use concurrent measurements and observationally constrained model simulations. In this dissertation a joint satellite-reanalysis approach is introduced, bridging the gap between climate models and satellite observations in a bottom-up approach. This methodology involves an observationally constrained aerosol model, refined and concurrent multi-component satellite retrievals, a state-of-the-art aerosol activation parameteriza- tion as well as radiative transfer model. This methodology is shown here to be useful for a quantitative as well as qualitative analysis of ACI and for estimating RFaci . As a result, a 10-year long climatology of cloud condensation nuclei (CCN) (particles from which cloud droplets form) is produced and evaluated. It is the first of its kind providing 3-D CCN concentrations of global coverage for various supersaturations and aerosol species and offering the opportunity to be used for evaluation in models and ACI studies. Further, the distribution and variability of the resulting cloud droplet numbers and their susceptibility to changes in aerosols is explored and compared to previous estimates. In this context, an analysis by cloud regime has been proven useful. Last but not least, the computation and analysis of the present-day regime-based RFaci represents the final conclusion of the bottom-up methodology. Overall, this thesis provides a comprehensive assessment of interactions and uncertainties related to aerosols, clouds and radiation in regimes of liquid water clouds and helps to improve the level of scientific understanding.

Es wird angenommen, dass die Zirkulation der Nordhemisphäre durch den Rückgang von Meereis in der Arktis und der Zunahme der Oberflächenalbedo in Sibirien beeinflusst wird. Letzteres wurde mit dem aktuellen atmosphärischen Zirkulationsmodell ICON getestet. Die Albedo über Sibirien wurde innerhalb eines Experimentes erhöht, und zwar auf Werte welche vergleichbar mit denen über dem grönländischen Eisschild sind. Es wurde festgestellt, dass in den Wintermonaten Dezember und Januar die vertikale Wellenausbreitung stärker in die Stratosphäre reicht; dem folgt auch die in der Theorie erwartete Erwärmung in der Stratosphäre. / The Northern hemisphere circulation is supposed to change due to changed sea-ice cover in the Arctic and the increase of Siberian surface albedo. The latter is tested using the state of the art atmospheric circulation model ICON. We artificially increased the albedo of Siberia to values comparable to the Greenland ice sheet to investigate the change of vertical wave propagation and the general change of the background circulation. It was found for the winter season that the increased albedo results in increased vertical wave propagation for December and January. This is accompanied by a warming of the stratosphere that was found for the whole winter.

The Greenland ice sheet is the largest Northern Hemisphere store of fresh water, and it is responding rapidly to the warming climate. In situ observations document the changing ice sheet properties in the lower accumulation area, Southwest Greenland. Firn densities from 1840 meters above sea level retrieved in May 2012 revealed the existence of a 5.5-meter-thick, near-surface ice layer in response to the recent increased melt and refreezing in firn. As a consequence, vertical meltwater percolation in the extreme summer 2012 was inefficient, resulting in surface runoff. Meltwater percolated and refroze at six meters depth only after the end of the melt season. This prolonged autumn refreezing under the newly accumulated snowpack resulted in unprecedented firn warming with temperature at ten meters depth increased by more than four degrees Celsius. Simulations confirm that meltwater reached nine meters depth at most. The refrozen meltwater was estimated at 0.23 meters water equivalent, amounting to 25 % of the total 2012 ablation. A surface energy balance model was used to evaluate the seasonal and interannual variability of all surface energy fluxes at that elevation in the years 2009 to 2013. Due to the meltwater presence at the surface in 2012, the summer-averaged albedo was significantly reduced (0.71 in 2012; typically 0.78). A sensitivity analysis revealed that 71 % of the subsequent additional solar radiation in 2012 was used for melt, corresponding to 36 % of the total 2012 surface lowering. This interplay between melt and firn properties highlights that the lower accumulation area of the Greenland ice sheet will be responding rapidly in a warming climate. / Stability and Variations of Arctic Land Ice (SVALI) / Programme for Monitoring of the Greenland Ice Sheet (PROMICE) / Greenland Analogue Project (GAP)

This thesis is based on measurements of aerosol optical and microphysical properties made at inland, coastal and island locations in India. Aerosol vertical distribution measurements have also been made both using surface based and aircraft borne instruments. In addition to these, satellite based measurements (MODIS and OMI) have also been used to estimate regional aerosol radiative forcing over the oceanic regions around India. The measurements at an inland, continental, urban location reveals the large effect of anthropogenic activities on aerosol characteristics at surface and the atmospheric vertical column. A clear seasonality is observed in aerosol optical and microphysical properties as a consequence of modulation by anthropogenic activities and the effect of meteorological parameters like rainfall, winds and boundary layer dynamics. The variability observed at different time scales (from diurnal, weekly, monthly to annual) reveals the importance of anthropogenic and natural processes in modulating the aerosol loading. The estimates of aerosol radiative forcing at surface were as high as ~ 40W m-2. A large discrepancy was observed between the observed and modeled aerosol forcing efficiency (forcing per unit optical depth) at surface. These discrepancies are due to the inadequate representation of aerosol mixing state in models. In addition, the large difference found in the observed forcing between winter and summer could also be influenced due to the presence of elevated aerosols during the summer. Measurements made over coastal and central India shows that a large fraction (75-85%) of aerosol column optical depth was contributed by aerosols located above 1 km. The horizontal gradients were sharp with e-1 scaling distance as small as ~250 km in the well-mixed regions mostly under the influence of local source effects. However, above the atmospheric boundary layer, the gradients were much shallower (~800 to 1200 km). In addition, a large fraction (60-75%) of aerosol was found located above clouds leading to enhanced aerosol absorption. Large spatial gradient in aerosol optical depth and hence radiative impacts between the coastal landmass and the adjacent oceans within a short distance of <300 km (even at an altitude of 3 km) during summer and pre-monsoon is of importance to regional climate. Observations at Minicoy, a remote island in southern Arabian Sea to study the characteristics of transported aerosols reveals variability at daily, weekly, monthly and seasonal time scales associated with changes in precipitation and air mass characteristics. The daily mean Black Carbon (BC) mass mixing ratio varied between as low as ~ 0.2 to 9.0%. The resultant average aerosol atmospheric forcing for the observation period was ~15 W m-2. Trajectory based cluster analysis has shown six distinct advection/transport pathways influencing aerosol characteristics over southern Arabian Sea. The Indo-Gangetic Plain, northern Arabian Sea and west Asia are identified to be the most important source regions having a major impact on aerosols loading over the southern Arabian Sea. The cluster analysis, concentration weighted trajectory (CWT) analysis and the MODIS retrievals show an asymmetry in aerosol characteristics between the Arabian Sea and the Bay of Bengal, with the Arabian Sea characterized by large loading by natural aerosols (eg., dust and sea salt) and the Bay of Bengal characterized by anthropogenic loading (eg., BC). The low value of the BC mass mixing ratio measured at the island (mostly ~ 1 to 1.6%), has major implications for regional radiative forcing. The annually averaged net aerosol atmospheric forcing was as low as ~1.7 W m-2 with highest forcing corresponding to IGP cluster. The single scattering albedo (SSA) which is an important parameter in the estimation of aerosol radiative forcing was retrieved by utilizing a joint OMI-MODIS retrieval methodology. The SSA over the oceanic regions around India shows that the largest absorption (SSA < 0.9) occurs during winter. The largest gradients in AOD and SSA were observed over Arabian Sea during the summer as a result of large dust emissions. The largest forcing observed also was confined to the northern Arabian Sea (~ 37 W m-2) as a result of high aerosol column loading and dust transport. The observed annual mean forcing at Minicoy were comparable to that estimated using satellite measurements, but were much lower than those observed during INDOEX.