A theoretical interpretation of ion composition measured on board the ‘Active’ satellite in the European sector during April 10-12, 1990 geomagnetic storm

Ion composition measurements on board the ACTIVE satellite during the recovery phase of a strong geomagnetic storm of 10–12 April 1990 revealed extremely high concentrations (up to 10³ cm⁻³) of the NO⁺, O⁺₂, N⁺₂ molecular ions in the topside F2-region of the European high-latitude zone. Concentrations of O⁺, N⁺, He⁺, H⁺ light ions were slightly decreased relative to prestorm quite conditions. Theoretical calculations were used to analyze the observed variations in ion concentration. Increased neutral temperature and [O₂], [N₂] are shown to be the main reasons for the observed ion concentration variations.     

Macroseismic effects related to strong ground motion: a study of the South Iceland earthquakes in June 2000

The impact of the June 2000 South Iceland earthquakes has been assessed applying data collected in field surveys and strong-motion recordings from the Icelandic Strong-Motion Network. The areas within approximately 20 km of the causative faults suffered considerable damage, including transportation and utility systems as well as buildings, both with regard to structure and inventories. Ground subsidence and dislocations were significant in the near-fault zone. Aftershocks and permanent displacements of building foundations resulted in progressive structural damage. By introducing holistic measures derived from the acceleration data, a fair correlation was achieved between the obtained earthquake intensities and the recorded accelerations. The measures adopted were square root of the sum of the squares (SRSS) values of peak ground acceleration (PGA) and the trace of the Arias intensity tensor. It was found that the overall attenuation tended to be more rapid than reflected by common strong-motion models reported in the literature. There is no simple explanation for this behaviour but it is reasonable to suggest that it can be partly attributed to the heterogeneous and fractured crust that is characteristic of Icelandic geology.     

Efficiency of reduced-order, time-dependent adjoint data assimilation approaches

Applications of adjoint data assimilation, which is designed to bring an ocean circulation model into consistency with ocean observations, are computationally demanding. To improve the convergence rate of an optimization, reduced-order optimization methods that reduce the size of the control vector by projecting it onto a limited number of basis functions were suggested. In this paper, we show that such order reduction can indeed speed up the initial convergence rate of an assimilation effort in the eastern subtropical North Atlantic using in situ and satellite data as constraints. However, an improved performance of the optimization was only obtained with a hybrid approach where the optimization is started in a reduced subspace but is continued subsequently using the full control space. In such an experiment about 50% of the computational cost can be saved as compared to the optimization in the full control space. Although several order-reduction approaches seem feasible, the best result was obtained by projecting the control vector onto Empirical Orthogonal Functions (EOFs) computed from a set of adjusted control vectors estimated previously from an optimization using the same model configuration.     

The quantitative IR spectroscopic determination of structural OH groups in kyanites

Summary Kyanites from different occurrences show in the near IR two relatively strong absorption bands at 3 380 and 3 270 cm^–1 due to OH stretching frequencies. The integral molar extinction coefficient is 3201 · Mol^–1 · cm^–2. A quantitative IR spectroscopic microtechnique based on Beer's law allows to determine small amounts of structural OH groups in (100) cleavage plates of a few tenths mm in size proved to be free of inclusions and hydrous alteration products. There exists an obvious relation between the occurrence of the kyanites studied and their equivalent H₂O⁺ content ranging from < 0.005 to 0.180 wt.%.

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Die quantitative IR-spektroskopische Bestimmung von strukturell gebundenen OH Gruppen in Kyaniten

Zusammenfassung Kyanite verschiedener Vorkommen zeigen im nahen IR bei 3 380 und 3 270 cm^–1 zwei relativ starke Absorptionsbanden, die von OH-Streckfrequenzen herrühren. Der integrale molare Extinktionskoeffizient beträgt 320 1 · Mol^–1 · cm^–2. Eine auf dem Beerschen Gesetz beruhende quantitative IR-spektroskopische Mikromethode erlaubt kleine Mengen strukturell gebundener OH-Gruppen in (100) Spaltplättchen einiger Zehntelmillimeter Größe, die einschlußfrei und frei von Umwandlungsprodukten sind, zu bestimmen. Es besteht offensichtlich eine Beziehung zwischen dem Vorkommen der untersuchten Kyanite und ihrem äquivalenten H₂O⁺-Gehalt, der sich von < 0.005 bis 0.180 Gew.-% erstreckt.

     

Towards a multi-scale approach for an Earth observation-based assessment of natural resource exploitation in conflict regions

The exploitation of resources, if not properly managed, can lead to spoiling natural habitats as well as to threatening people’s health, livelihoods and security. The paper discusses a multi-scale Earth observation-based approach to provide independent information related to exploitation activities of natural resources for countries which are experiencing armed conflict. The analyses are based on medium to very high spatial resolution optical satellite data. Object-based image analysis is used for information extraction at these different scales. On a subnational level, conflict-related land cover changes as an indication of potential hot spots for exploitation activities are classified. The regional assessment provides information about potential activity areas of resource exploitation, whereas on a local scale, a site-specific assessment of exploitation areas is performed. The study demonstrates the potential of remote sensing for supporting the monitoring and documentation of natural resource exploitation in conflict regions.     

A decade of Predictions in Ungauged Basins (PUB)—a review

Abstract

The Prediction in Ungauged Basins (PUB) initiative of the International Association of Hydrological Sciences (IAHS), launched in 2003 and concluded by the PUB Symposium 2012 held in Delft (23–25 October 2012), set out to shift the scientific culture of hydrology towards improved scientific understanding of hydrological processes, as well as associated uncertainties and the development of models with increasing realism and predictive power. This paper reviews the work that has been done under the six science themes of the PUB Decade and outlines the challenges ahead for the hydrological sciences community.

Editor D. Koutsoyiannis

Citation Hrachowitz, M., Savenije, H.H.G., Blöschl, G., McDonnell, J.J., Sivapalan, M., Pomeroy, J.W., Arheimer, B., Blume, T., Clark, M.P., Ehret, U., Fenicia, F., Freer, J.E., Gelfan, A., Gupta, H.V., Hughes, D.A., Hut, R.W., Montanari, A., Pande, S., Tetzlaff, D., Troch, P.A., Uhlenbrook, S., Wagener, T., Winsemius, H.C., Woods, R.A., Zehe, E., and Cudennec, C., 2013. A decade of Predictions in Ungauged Basins (PUB)—a review. Hydrological Sciences Journal, 58 (6), 1198–1255.     

Seismic Attenuation in Partially Saturated Dime-shaped Cracks

—We have examined the effect of surface contamination on the attenuation and stiffness of compressional seismic waves in artificial cylindrical glass cracks that are partially saturated with water. The compression of the gap perpendicularly to its plane reduces the gap volume and forces the water to redistribute within the gap (conservation of volume of an incompressible liquid). On clean surfaces, the water can flow without significant resistance across the glass. This leads to a very low and almost constant attenuation over a wide frequency range (approx. 3 mHz to 10 Hz), while the sample stiffness is constant. In the case of propanol contaminated surfaces, both the attenuation and the stiffness are considerably higher than in the clean case, and display a considerable frequency dependence. Both effects can be explained with the Restricted Meniscus Motion Model. In this model, the redistribution of the liquid in the gap first leads to a change (increase) of the contact angle. The change of the meniscus curvature results in an increase of the pressure in the liquid and thus to a stiffening of the sample. When the resistive force, that prevents the contact line from sliding along the surface, is finally overcome, the contact line starts moving across the contaminated surface. The motion against the resistive force dissipates energy and increases the attenuation. The calculated data are in good agreement for both the clean and the contaminated case; the model parameters fall in the range that was established by independent experiments (e.g. ).     

Kamarizaite,Fe<Stack><Subscript>3</Subscript><Superscript>3+</Superscript></Stack>(AsO<Subscript>4</Subscript>)<Subscript>2</Subscript>(OH)<Subscript>3</Subscript> · 3H<Subscript>2</Subscript>O,a new mineral species,arsenate analogue of tinticite

Kamarizaite, a new mineral species, has been identified in the dump of the Kamariza Mine, Lavrion mining district, Attica Region, Greece, in association with goethite, scorodite, and jarosite. It was named after type locality. Kamarizaite occurs as fine-grained monomineralic aggregates (up to 3 cm across) composed of platy crystals up to 1 μm in size and submicron kidney-shaped segregations. The new mineral is yellow to beige, with light yellow streak. The Mohs hardness is about 3. No cleavage is observed. The density measured by hydrostatic weighing is 3.16(1) g/cm³, and the calculated density is 3.12 g/cm³. The wavenumbers of absorption bands in the IR spectrum of kamarizaite are (cm^?1; s is strong band, w is weak band): 3552, 3315s, 3115, 1650w, 1620w, 1089, 911s, 888s, 870, 835s, 808s, 614w, 540, 500, 478, 429. According to TG and IR data, complete dehydration and dehydroxylation in vacuum (with a weight loss of 15.3(1)%) occurs in the temperature range 110–420°C. Mössbauer data indicate that all iron in kamarizaite is octahedrally coordinated Fe³⁺. Kamarizaite is optically biaxial, positive: n _min = 1.825, n _max = 1.835, n _mean = 1.83(1) (for a fine-grained aggregate). The chemical composition of kamarizaite (electron microprobe, average of four point analyses) is as follows, wt %: 0.35 CaO, 41.78 Fe₂O₃, 39.89 As₂O₅, 1.49 SO₃, 15.3 H₂O (from TG data); the total is 98.81. The empirical formula calculated on the basis of (AsO₄,SO₄)₂ is Ca_0.03Fe _2.86 ³⁺ (AsO₄)_1.90(SO₄)_0.10(OH)_2.74 · 3.27H₂O. The idealized formula is Fe ₃ ³⁺ (AsO₄)₂(OH)₃ · 3H₂O. Kamarizaite is an arsenate analogue of orthorhombic tinticite, space group Pccm, Pcc2, Pcmm, Pcm2₁, or Pc2m; a = 21.32(1), b = 13.666(6), c =15.80(1) Å, V= 4603.29(5) ų, Z= 16. The strongest reflections of the X-ray powder diffraction pattern [\(\bar d\), Å (I, %) (hkl)] are: 6.61 (37) (112, 120), 5.85 (52) (311), 3.947 (100) (004, 032, 511), 3.396 (37) (133, 431), 3.332 (60) (314), 3.085 (58) (621, 414, 324). The type material of kamarizaite is deposited in the Mineralogical Collection of Technische Universität Bergakademie Freiberg, Germany, inventory number 82199.