In this diploma thesis, the diurnal changes of initial and total Rubisco activity and Rubisco enzyme content in beech (Fagus sylvatica) were studied under conditions of ambient (A) CO2 concentration (350 µmol.mol-1) and elevated (E) CO2 concentration (700 µmol.mol-1) during the day. Samples were taken on July 8th (from 10:00 to 21:30), on July 9th (from 04:00 to 12:00) and then on July 22th (from 04:00 to 21:30). The initial and total activity were measured spectrophotometrically and the activation level was calculated from the ratio of initial and total activities. Rubisco enzyme content was determined by SDS-PAGE method and the initial and total specific activity were calculated from the ratio of initial or total activity and Rubisco enzyme content. In our experiment no statistically significant difference was found between Rubisco activities in beeches cultivated under conditions of ambient CO2 concentration and elevated CO2 concentration, so any down-regulation of Rubisco activity did not appear under the influence of ambient CO2 concentration. Diurnal changes of Rubisco activities showed only statistically nonsignificant fluctuation. After daylight no significant increase of total Rubisco activity was observed, which demonstrates the absence or the immaterial effect of CA1P night inhibitor in beech. Intensive fluctuation of the activation level (40–90 %) proves the regulation of photosynthesis during the day via Rubisco enzyme carbamylation. Rubisco enzyme content in beech cultivated under conditions of ambient CO2 concentration was lower than that one in beech cultivated under conditions of elevated CO2 concentration. Then down-regulation of Rubisco enzyme content is presented under conditions of ambient CO2 concentration. Before daylight Rubisco enzyme content showed an indistinctive minimum on the level of statistical significance, during the day only nonrelevant fluctuation was noticed.

MENVSC (Geography) / Department of Geography and Geo-Information Sciences / Rainfall is undoubtedly the most significant factor for life’s continuity. South Africa is prone to future climate uncertainties due to global climate change. The aim of this study is to investigate rainfall variability and change in South Africa on a present day (1976-2005), near-future (2006-2035) and far-future (2036-2065) climate. For the study, 3 RCMs (REMO2009, RCA4 and CCLM4-8-17), forming part of CORDEX-Africa project were nested within 5 different CIMP5_GCMs of low resolution. GPCC precipitation, NOAA GHCN_CAMS Land Temperature and other NCEP reanalysis products were useful in validating models in simulations of present-day climate. RCP4.5 and RCP8.5 emission scenarios from IPCC-AR5 were used for future climate projections. On the validation, each regional climate model displayed different signature on simulations, rainfall in particular because this is a variable that is affected most by sub-grid process. Simulations nested within MIROC5 simulated more precipitation than simulations forced with other GCMs, due to more large-scale moisture convergence into the nested domain. There were differences in projections of RCM nested within the same GCM, as well as with the same RCM nested within different GCMs, on the future. Models nested within MPI project wetter conditions over the eastern parts of Limpopo, while the other two projected drier conditions in the same area. REMO2009 forced on MPI uniquely projected drying of Western Cape throughout the seasons on both RCPs and futures. Simulations conducted with the RCP8.5 scenario forcing are generally found to be associated with either a larger increase in temperature, or an increase in area associated with higher temperature increases. CCLM4-8-17 forced on HadGEM2 projected below average temperatures over the northwest parts of the country under the RCP8.5 scenarios. MPI driving model projected a general reduction of evaporation values, with lowest over northeast, northwest parts and south coastal parts of South Africa, in contrary to adjacent oceans. In this study, we have sought to identify the sources of uncertainties amongst model simulations between either the RCMs or the driving GCMs. / NRF

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In first part of the study we discuss impact of dynamical core in simulation of tropical rainfall. Over years many new dynamical cores have been developed for atmospheric models to increase efficiency and reduce numerical errors. CAM3.1 gives an opportunity to study the impact of the dynamical core on simulations with its three dynamical cores namely Eulerian spectral(EUL) , Semilagrangian dynamics(SLD) and Finite volume(FV) coupled to a single parametrization package. A past study has compared dynamical cores of CAM3 in terms on tracer transport and has showed advantages using FV in terms of tracer transport. In this study we compare the dynamical cores in climate simulations and at their optimal configuration, which is the intended use of the model. The model is forced with AMIP type SST and rainfall over seasonal, interannual scales is compared. The significant differences in simulation of seasonal mean exist over tropics and over monsoon regions with observations and among dynamical cores. The differences among EUL and SLD, which use spectral transform methods are lesser compared that of with FV clearly indicating role of numerics in differences. There exist major errors in simulation of seasonal cycle in all dynamical cores and errors in simulation of seasonal means over many regions are associated with errors in simulation of seasonal cycle such as over south china sea. Seasonal cycle in FV is weaker compared to SLD and EUL. The dynamical cores exhibit different interannual variability of rainfall over Indian monsoon region, the period of maximum power corresponding to a dynamical core differs substantially with another. From this study there seems no superiority associated with FV dynamical core over all climate scales as seen in tracer transport. The next part of the study deals with impact of diurnal ocean atmosphere coupling in an AGCM,CAM3.1. Due to relatively low magnitude of diurnal cycle of SST and lack of SST observations over diurnal scales current atmospheric models are forced with SSTs of periods grater than a day. CAM 3.1 standalone model is forced with monthly SSTs but the interpolation is linear to every time step between any two months and this linear interpolation implies a linear diurnal and intraseasonal variation of SST which is not true in nature. To test the sensitivity of CAM3.1 to coupling of SST on diurnal scales, we prescribed over tropics(20S20N) a diurnal cycle of SST over daily mean interpolated SST of different magnitudes and phase comparable to observations. This idea of using a diurnal cycle of SST retaining seasonal mean SST in an atmospheric model is novel and provides an interesting frame work to test sensitivity of model to interpolations used in coupling of boundary conditions. Our analysis shows a high impact of using diurnal cycle of SST on simulation of mean rainfall over tropics. The impact in a case where diurnal cycle of SST is fixed and retained to daily mean SST implies that changes associated with a coupled model are to some extent due to change in representation of diurnal cycle of SST. A decrease of excess rainfall over western coast of Bay of Bengal and an increase of rainfall over northern bay of Bengal in such case is similar to the improvement due to coupling atmospheric model to a slab ocean model. This also implies that problems with current AMIP models in simulation of seasonal mean Indian monsoon rainfall could be due to erroneous representation of diurnal cycle of SST in models over this region where the diurnal cycle of SST is high in observations. The high spatial variability of the impact in various cases over tropics implies that a similar spatial variation of diurnal cycle could be important for accurate simulation of rainfall over tropics. Preliminary analysis shows that impact on rainfall was due to changes in moisture convergence. We also hypothesized that diurnal cycle of SST could trigger convection over regions such as northern Bay of Bengal and rainfall convergence feedback sustains it. The impact was also found on simulation of internal interannual variability of rainfall

Weather radars are increasingly used for the study of clouds, understanding the precipitation systems and also for forecasting very short range weather (one hour to a few hours). Now, Doppler Weather Radar (DWR) data are available in India and it is possible to study cloud properties at fine temporal and spatial scales. Radar is a complex system and calibration of a radar is not an easy job. But derived cloud properties strongly depend on the absolute magnitude of the reflectivity. Therefore, there is a need to check how data from two or more radars compare if they measure a common volume. Chennai and SHAR radars are within 66 km from each other, and the data collected during their calibration and intercomparison experiment in 2006 enables the comparison of their reflectivity(Z) values. Individual reflectivity are compared after plotting SHAR versus Chennai in a scatter plot. Fitting a least square linear best fit line shows that the intercept has a value around 6 dBZ and the slope of the line is 1.06. Thus, there is a trend as well, and the difference between the two radars increase with Z, and for Z around 40 dBZ (for SHAR DWR), the difference between the two is around 8.5 dBZ. Visual intercomparison also validated the results. Data from the two radars are compared with Precipitation Radar (PR) data on board TRMM satellite. TRMM radar slightly overestimates compared to Chennai radar above the range of 30 dBZ. After standardized, SHAR data is used for understanding the evolution and propagation of cloud systems. The diurnal variation in convection is strong in the study region, with increase around local evening and morning and weakening around midnight except in December. Average liquid water content in the clouds is about 0.5 gm/m3. There is some seasonal dependence but no clear dependence on cloud size. Smaller systems of May have more liquid water content compared to larger ones. For nowcasting vertically projected maximum reflectivity is taken. A threshold of 30 dBZ is set to identify the cloud systems. Both center of gravity tracking (CG) and cross-correlation (CC) methods are used to track them. Frequent merging and splitting is common in the clouds which makes storm tracking difficult. Tracking by CC is giving better result than that by the CG method in the case of large systems (i.e., clusters). For smaller systems (individual cloud systems), CC method gives better result than CG method but not as good as cluster.

From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / A study was made to determine how the evaporation rate from a bare Adelanto loam soil in Phoenix changes with season and with time since the last irrigation. The evaporation rates were determined by precision lysimeters in a bare field, with measurements being taken in every month of the year for at least a week after irrigation. The data exhibited a cosine-shaped curve, with a maximum evaporation rate of about 5 mm/day in summer and a minimum rate of about 2 mm/day in winter. By the seventh day, seasonal effects virtually disappear, and the evaporation rate is the same in both summer and winter, being about 2 mm/day after the 7th day and about 0.75 mm/day after the 21st day. It is generally accepted that soil dries in 3 stages, and the transition between the 1st and 2nd stages occurs when atmospheric conditions are no longer critical. In previous laboratory studies of soil drying, with constant atmospheric conditions, stage 1 was easily distinguished from stage II, and these results correlated closely with the equations of Gardner and Hillel. The individual drying curves of this field study were qualitatively different from the laboratory studies and did not confirm the predictions of the equations, suggesting that diurnal variations in temperature and other meteorological parameters have caused the difference.

From the Proceedings of the 1977 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 15-16, 1977, Las Vegas, Nevada / Relative water content (RWC), water potential (P), and gas exchange were measured on saltcedar at the Bernardo, New Mexico, lysimeter site. RWC and s were closely correlated; but, water potential measurements, taken with a pressure bomb, were more convenient and reliable. RWC and r decreased sharply from sunup until about 0900, when minimum values of about -26 bars T or 80% RWC were reached. Water status then remained constant or improved slightly through late afternoon. Transpiration rates typically remained high until about noon and then began a steady, gradual decrease that continued throughout the afternoon. The data suggest that water stress may be a factor in initiating stomatal closure; however, transpiration continued to decline despite a constant or improved leaf water status. Maximum net photosynthetic rates occurred by 0900, and depressions throughout the remainder of the day were largely accounted for by increased leaf temperatures. Afternoon depressions in transpiration and photosynthesis occurred in twigs held at constant temperature and relative humidity, suggesting that a diurnal rhythm may be involved in control of gas exchange. Water status of plants growing on the lysimeters was comparable to that of plants in adjacent natural stands; gas exchange rates were slightly higher for the lysimeter-grown plants.

With a surface area of about 10,000 km², the Salar de Uyuni is the largest salt flat in the world. It is located at an altitude of 3,653 m on the Altiplano, a high plateau in the south of the Bolivian Andes. The Salar de Uyuni consists of an alternating sequence of highly porous salt layers (mainly composed of halite) and lacustrine clay sediments. The pore volume of the uppermost salt layer which has a thickness of up to 11 m is filled by brine. The brine contains high amounts of Mg, K, Li and B. The element lithium is an especially important raw material for the production of batteries. Thus, it plays an important role for the development of the electric mobility. With this background, extensive hydrogeological exploration activities were carried out at the Salar de Uyuni in the context of this dissertation. The hydraulic properties of the uppermost salt crust and the physical properties (density and viscosity) of the brine must be characterized. In order to do this, several core drillings were made, observation wells were installed, brine samples were taken and pumping tests were conducted between 2009 and 2012. The stratigraphic documentation of the obtained sediment cores provided insights about the deposit structure and the upper salt layer thickness. The determination of the salt core porosity was carried out by three different methods: (a) by using X-ray computed tomography, (b) gravimetrically by saturation with 2-octanol and (c) by completion of the core volume with plasticine and calculation of the porosity under consideration of the particle density of the salt. The laboratory investigations showed a depth-dependent porosity distribution in the upper salt layer. The uppermost 2 m were characterized by very high porosity values between 30 and 39%. However at greater depth, the total porosity decreases on average to 13.5%. Geochemical analyses of brine samples confirmed the general spatial distribution of the lithium concentrations as already published by previous studies. On the basis of the lithium distribution in the brine, the thickness of the upper salt layer and the depth-dependent porosity distribution, the total lithium deposit in the Salar de Uyuni was calculated to be about 7 million tons. The evaluation of the pumping tests under consideration of the density and viscosity of the pumped brine showed that the salt has a very high permeability in the horizontal direction. In contrast, flow-through experiments on drill cores indicated a clear vertical anisotropy of the permeability. This is caused by the inhomogeneous sediment stratification for instance by interbedded fine gypsum or clay lamina. Thus, horizontal brine movements are possible, but a deep vertical flow component can hardly be expected. This assumption is confirmed by radiocarbon dating the brine samples from different salt depths. The influence of annual floods during the rainy season could be observed by long-term brine level measurements. Throughout the time-series analysis, distinct periodic brine fluctuations of a few centimeters per day could be identified during the dry season. These daily fluctuations indicated an impermeable crust probably formed by the evaporation of near-surface brine and subsequent crystallization of salts in the pore volume. Thus, daily temperature and atmospheric pressure changes could directly affect the brine level. Due to the extensive hydrogeological investigations, this dissertation contributes to the essential understanding of the hydraulic conditions in the Salar de Uyuni. / Mit einer Fläche von rund 10.000 km² ist der Salar de Uyuni die größte Salz-Ton-Ebene der Welt. Er befindet sich in einer Höhe von 3653 m NN im Altiplano, einer Hochebene im Süden der bolivianischen Anden. Der Salar de Uyuni besteht aus einer Wechsellagerung von hochporösen Salzschichten (überwiegend aus Halit bestehend) und lakustrinen Tonsedimenten. Die Porenräume der obersten bis zu 11 m mächtigen Salzschicht sind mit einer Sole gefüllt, die hohe Gehalte an Mg, K, Li und B aufweist. Insbesondere das Element Lithium ist ein wichtiger Rohstoff u.a. für die Herstellung von Batterien und spielt damit eine bedeutende Rolle bei der Entwicklung der Elektromobilität. Vor diesem Hintergrund wurden im Rahmen der vorliegenden Dissertation umfassende hydrogeologische Erkundungsarbeiten am Salar de Uyuni durchgeführt, um die hydraulischen Eigenschaften der obersten Salzkruste sowie die physikalischen Eigenschaften (Dichte und Viskosität) der Sole zu charakterisieren. Dazu wurden zwischen 2009 und 2012 zahlreiche Kernbohrungen abgeteuft, Beobachtungsbrunnen installiert, Soleproben entnommen und Pumpversuche durchgeführt. Die stratigraphische Dokumentation der gewonnenen Bohrkerne lieferte Erkenntnisse zur Ablagerungsstruktur und zur Mächtigkeitsverteilung der obersten Salzschicht. Die Bestimmung der Porosität der Salzkerne erfolgte mit drei verschiedenen Methoden: (a) mittels Computertomographie, (b) gravimetrisch durch Aufsättigung mit 2-Oktanol und (c) durch Volumenergänzung der Kernproben mit Plastilin und Berechnung der Porosität unter Einbeziehung der Reindichte des Salzes. Die Laboruntersuchungen zeigten eine tiefenabhängige Porositätsverteilung in der obersten Salzschicht. Während die obersten 2 m durch sehr hohe Porositäten zwischen 30 und 39% gekennzeichnet sind, nimmt die Gesamtporosität in größerer Tiefe auf durchschnittlich 13.5% ab. Geochemische Analysen von Soleproben bestätigten die grundsätzliche räumliche Verteilung der Lithium-Konzentrationen, wie sie bereits durch frühere Studien veröffentlicht wurde. Auf Basis der Lithium-Verteilung in der Sole, der Mächtigkeit der oberen Salzschicht sowie der tiefenabhängigen Porositätsverteilung wurde ein Lithium-Vorkommen im Salar de Uyuni von rund 7 Millionen Tonnen berechnet. Die Auswertung der Pumpversuche unter Berücksichtigung der Dichte und Viskosität der geförderten Sole zeigte, dass das Salz eine sehr hohe Permeabilität in horizontaler Richtung aufweist. Allerdings zeigten Durchströmungsversuche an Bohrkernen eine deutliche vertikale Anisotropie der Permeabilität, was auf die inhomogene Sedimentschichtung durch z.B. eingeschaltete feine Gips- oder Tonschichten zurückzuführen ist. Somit sind zwar horizontale Solebewegungen möglich, jedoch ist kaum mit einer tiefgreifenden vertikalen Strömungskomponente in der Salzschicht zu rechnen. Diese Vermutung wird durch 14C-Altersdatierungen von Soleproben aus unterschiedlichen Tiefen des Salzes bestätigt. Der Einfluss der jährlichen Überschwemmungen während der Regenzeit konnte anhand von Langzeitmessungen des Solespiegels beobachtet werden. Im Zuge der Zeitreihen-Analyse zeigten sich zudem ausgeprägte periodische Tageschwankungen von einigen Zentimetern während der Trockenzeit. Diese deuten darauf hin, dass durch Verdunstung oberflächennaher Sole und damit einhergehender Kristallisation von Salzen im Porenraum eine undurchlässige Kruste entsteht. Dadurch haben tägliche Temperatur- und Luftdruckschwankungen direkten Einfluss auf den Solespiegel. Die vorliegende Dissertation trägt aufgrund der umfangreichen hydrogeologischen Untersuchungen wesentlich zum Verständnis der hydraulischen Verhältnisse im Salar de Uyuni bei. / Con una superficie de aproximadamente 10.000 kilómetros cuadrados el Salar de Uyuni es el mayor lago de sal en el mundo. Se encuentra a una altura de 3.653 m sobre el nivel del mar en el altiplano en el sur de los Andes bolivianos. El Salar de Uyuni consiste en una alternancia de capas de sal altamente porosa (que consiste predominantemente de halita) y lacustre sedimentos de arcilla. La capa superior de sal tiene un espesor de hasta 11 metros. Los espacios de poros del sal se llenan con una salmuera que contiene altos contenidos de Mg, K, Li y B. En particular, el elemento litio constituye una importante materia prima para la producción de baterías que son utilizadas en la construcción de vehículos eléctricos. Bajo estos antecedentes y en el contexto de la presente tesis, se han desarrollado extensas actividades de exploración hidrogeológica en el Salar de Uyuni. Las propiedades hidráulicas de la corteza de sal superior y las propiedades físicas (densidad y viscosidad) de la salmuera debían caracterizadas. Para ello, entre 2009 y 2012 se realizaron varios perforaciones con la finalidad de obtener muestras de núcleos, se instalaron pozos de supervisión, se realizaron pruebas de bombeo y se tomaron muestras de salmuera. La documentación estratigráfica de los núcleos de perforacíon proporciona conocimientos para la estructura de los depósitos y para el espesor del superior capa de sal. La porosidad de los núcleos de sal fue determinada por medio de tres métodos diferentes: (a) por tomografía computarizada (TC), (b) gravimétricamente mediante la saturación con 2-octanol y (c) mediante de compleción del volumen del núcleo con plastilina y computacíon de la porosidad en atención a la densidad real del sal. Las investigaciones de laboratorio demostraron una distribución de la porosidad dependiente de la profundidad en la capa superior de sal. Mientras que la parte superior 2 m se caracterizan por altas porosidades entre el 30 y 39%, la porosidad total decrese en una profundidad mayor a un promedio de 13,5%. Los análisis geoquímicos de muestras de salmuera confirmaron la distribución espacial fundamental de las concentraciones de litio, como ya se ha publicado por estudios anteriores. A base de la distribución de litio en la salmuera, el espesor de la capa superior de sal, y la porosidad dependiente de la profundidad determinaron que todos los recursos minerales de litio en el salar de Uyuni son alrededor de 7 millones de toneladas. La evaluación de las pruebas de bombeo en consideración de la densidad y la viscosidad de la salmuera transmitido mostró que la sal generalmente tiene una permeabilidad muy alta. Pero, las pruebas de flujo en muestras de núcleo mostró una anisotropía significativa de la permeabilidad con la profundidad, que se debe a una estratificación de sedimentos no homogénea debido las láminas finas de yeso o arcilla intercaladas. Por lo tanto, es correcto que los movimientos de salmuera horizontales son posibles, pero es poco probable que movimientos verticales de salmuera ocurran. Esta hipótesis se ve confirmada por la datación por radiocarbono de muestras de salmuera de diferentes profundidades de la sal. El impacto de las inundaciones anuales durante la estación lluviosa se puede observar a partir de las mediciones a largo plazo del nivel de salmuera. En el curso del análisis de series de tiempo también mostraron pronunciadas variaciones diarias periódicas de unos pocos centímetros en la estación seca. Esto sugiere que hay una corteza impermeable que se forma por evaporación de salmuera cerca de la superficie y la cristalización de sales en el espacio de los poros. En esta manera, las fluctuaciones diarias de temperatura y de preción de aire influyen directamente el nivel de salmuera. Gracias a las extensas investigaciones hidrogeológicas realizadas, la presente tesis contribuye significativamente a la comprensión de las condiciones hidráulicas en el Salar de Uyuni.