Analysis of daily rainfall processes in lower extremadura (Spain) and homogenization of the data

Summary In this paper we analyze, from the point of view of stochastic processes, daily rainfall data recorded at the Badajoz Observatory (Southwestern Spain) since the beginning of the century. We attempt to identify any periodicities or trends in the daily rainfall occurrences and their dependence structure, and attempt to select the appropriate point stochastic model for the daily rainfall series.Standard regression analysis, graphical methods and the Cramer statistic show a rise in the number of cases of light rain (between 0.1 and 5 mm/d) and a decline in the number of cases of moderate to heavy rain (> 5 mm/d) in the daily rainfall at least at the 5% significance level.That the homogenization process was satisfactory is shown by the mean interarrival time of the homogenized series and the test of the rate of homogenized daily rainfall occurrences. Our analysis also shows that the behavior of the spectra of the homogenized daily rainfall counts is completely different from that of a Poisson process, so that the hypothesis of a non-homogeneous Poisson process is rejected.With 7 Figures     

Nonlinear wave conversion in electron-positron plasmas

Wave conversion mechanisms causing large-frequency shifts are considered for an electron-positron plasma in a strong magnetic field. In particular, we discuss the effects of the nonlinear erenkov as well as the cyclotron resonances in order to associate pulsar radio-emissions with our present model for nonlinear conversion of high-frequency radiation into the low-frequency region.     

Stratiform and vein U,Mo and Cu mineralization in the Novoveská Huta area,CSFR

U-Mo and Cu mineralization occurs in horizons as well as in veins in the Permian formations near Novoveská Huta. Ore mineralization is represented by uraninite, U-Ti oxides, coffinite, molybdenite, chalcopyrite, tennantite and pyrite. The isotopic composition of S and C displays a larger variability in the stratiform ores (³⁴S from –32.7 to +2.7 and ¹³C from –27.1 to — 0.5) These data suggest mixing of meteoric solutions with fluids of volcanic origin and a complex history. There is a narrower range of ³⁴S from –18.8 to –4.6 and ¹³C from –6.3 to –2.5% in quartz-carbonate veins with Cu mineralization suggesting a deep source of ore-bearing solutions. The Permian volcanics were a significant source of ore elements.Their contents of U, Mo, Cu and Y are from two to eight times higher than in sedimentary rocks. Accumulations of ore elements in the horizons were formed by the reduction and adsorption processes 240 ± 30 Ma ago according to U-Pb isotopic dating. Due to Alpine tectonism, these low-grade ores (U<0.1 wt%) were remobilized and higher-grade U-Mo ores (U>0.1 wt%) were formed 130 ± 20 Ma ago at temperatures ranging from 110 to 120° C, according to fluid inclusions. Younger veins with Cu mineralization were formed 115 ± 10 Ma according to the model age of Pb at temperatures ranging from 95 to 190°C.     

Structure of the αFexAl1:xOOH solid solution

The three-dimensional local organisation around Fe atoms in a natural diaspore (Al_0.9955Fe_0.0045OOH) has been investigated by angular measurements of X-ray absorption spectra. It is demonstrated that in a single crystal of diaspore, the absorption cross-section exhibits the special case of trichroism where three independent measurements are needed to determine the absorption cross-section for any direction of polarization. Extended X-ray absorption fine structure (EXAFS) spectra were thus recorded at the following orientations of the polarization vector: , , and . The incoming white beam was monochromatized using two Si(331) crystals, which deliver at the Fe K-edge a completely linearly polarized X-ray beam. The reliability of our measurements was checked by comparing the isotropic EXAFS spectrum calculated from the three orthogonal measurements to the one of the diaspore powder recorded at the magic angle. It is shown that Fe³⁺ ions are not randomly distributed within the diaspore framework. Furthermore, only part of the Fe³⁺ ions substitutes Al, the others being located in the channels of the structure. The 3D local structure of the Fe domains has been modeled assuming hematite-like clusters of three Fe octahedra topotactically grafted to aluminous chains. These Fe clusters are thought to represent ancient multinuclear Fe surface complexes having formed at the time of the diaspore growth, and being sealed in its bulk structure. The whole crystal of diaspore is then thought to have kept the memory of the heterogeneous nucleation mechanism of these hematite nuclei. In addition to the well-known examples of atom segregations, ion vacancies, and intergrowths of discrete phases, this new type of crystal defect represents another evidence of non-equilibrium crystallization process under the thermodynamic and kinetic conditions that prevail at the earth's surface.     

Using δN values in algal tissue to map locations and potential sources of anthropogenic nutrient inputs on the island of Maui, Hawai‘i, USA

Macroalgal blooms of Hypnea musciformis and Ulvafasciata in coastal waters of Maui only occur in areas of substantial anthropogenic nutrient input, sources of which include wastewater effluent via injection wells, leaking cesspools and agricultural fertilizers. Algal δ¹⁵N signatures were used to map anthropogenic nitrogen through coastal surveys (island-wide and fine-scale) and algal deployments along nearshore and offshore gradients. Algal δ¹⁵N values of 9.8‰ and 2.0-3.5‰ in Waiehu and across the north-central coast, respectively, suggest that cesspool and agricultural nitrogen reached the respective adjacent coastlines. Effluent was detected in areas proximal to the Wastewater Reclamation Facilities (WWRF) operating Class V injection wells in Lahaina, Kihei and Kahului through elevated algal δ¹⁵N values (17.8-50.1‰). From 1997 to 2008, the three WWRFs injected an estimated total volume of 193 million cubic meters (51 billion gallons) of effluent with a nitrogen mass of 1.74 million kilograms (3.84 million pounds).     

Magnetometer Array Study in North-Northeast Brazil: Conductivity Image Building and Functional Induction Modes

—Magnetovariational fields recorded by an array of magnetometers in the equatorial region of north-northeast Brazil are analyzed to infer the configuration of internal induced currents in and around the extensive intracratonic Parnaíba basin. Only nighttime magnetovariational fields were used because of the prevailing uniform source field conditions. For periods exceeding 40 min. the vertical fields at all inland sites are dominated by the effects of electric currents originating in the northeast, in the deep Atlantic Ocean. Below this period, although best developed in the 12–15 min. period range, the anomalous signatures are principally controlled by two distinct continental current paths. The first is associated with a N60°E trending graben-like structure in the southeastern part of the basin (named the Parnaíba Basin Conductivity Anomaly—PBCA) and the second appears as a subsurface sedimentary channel, from the NW corner of the array to the central part of the basin. This is named the LINK anomaly, as it connects the northwestern Marajó basin with the Parnaíba basin. While the PBCA is shown to highlight the importance of basement tectonics in the geological evolution of the Parnaíba basin, the LINK anomaly provides strong geophysical evidence of the direction of the sea intrusion into the region of the basin and possibly indicates the connectivity of the Parnaíba basin to the adjoining Amazon basin through the Marajó basin. Frequency and polarization dependence suggest that the induction response of individual structures is not determined by the local conductivity alone but also by their interconnectivity as well as by their linkage to the continental shelf and deep oceanic region.