Planetary waves in the mesosphere lower thermosphere during stratospheric sudden warming: observations using a network of meteor radars from high to equatorial latitudes

Climate Dynamics - In the present communication, characteristics of mean winds and planetary waves in the mesosphere lower thermosphere (MLT) region during sudden stratospheric warming (SSW) events...     

Hydrostratigraphic framework and hydrogeological behaviour of the Mancha Oriental System (SE Spain)

The Mancha Oriental System (MOS) has a surface area of 7,260 km², making it one of the largest carbonate aquifer systems in Spain. The system sustains about 1,000 km² of irrigated crops and supplies groundwater to 275,000 inhabitants. The economic transformation brought about by the development of extensive irrigated cropland has led to a water-balance disequilibrium of about 75 million m³/year. This input–output deficit has negative consequences in the quantity and quality of the available resources, in the river–aquifer relationship, and in the associated ecosystems as well. To understand the hydrogeological behaviour of the system, it is necessary to design a conceptual model. Further, the conceptualisation of a groundwater flow system is a requirement of the European Water Framework Directive for the characterisation of groundwater bodies. The robustness of the conceptual model depends heavily on the user capability of representing the real system. In this work, a multidisciplinary approach has been used to represent the three-dimensional geological framework and the groundwater flow conceptualisation of the MOS. Data management and three-dimensional visualisation have been carried out by means of geographical information system (GIS) tools and software for contouring and three-dimensional surface mapping.     

A sociodemographic typology of middle-level regions in the USSR

"Oblast-level regions of the USSR are grouped and mapped in nine types and a number of subtypes to reflect a combination of demographic factors: level of urbanization, urban and rural population growth, and population density. The typology can be used to devise sets of spatially differentiated measures to carry out a demographic policy and to regulate the sociodemographic evolution of regions."     

Geological,fluid inclusion and stable isotope studies of Mo mineralization,Galway Granite,Ireland

Mo mineralization within the Galway Granite at Mace Head and Murvey, Connemara, western Ireland, has many features of classic porphyry Mo deposits including a chemically evolved I-type granite host, associated K- and Si-rich alteration, quartz vein(Mace Head) and granite-hosted (Murvey) molybdenite, chalcopyrite, pyrite and magnetite mineralization and a gangue assemblage which includes quartz, muscovite and K-feldspar. Most fluid inclusions in quartz veins homogenize in the range 100–350°C and have a salinity of 1–13 eq. wt.% NaCl. They display Th-salinity covariation consistent with a hypothesis of dilution of magmatic water by influx of meteoric water. CO₂-bearing inclusions in an intensely mineralized vein at Mace Head provide an estimated minimum trapping temperature and pressure for the mineralizing fluid of 355°C and 1.2 kb and are interpreted to represent a H₂O-CO₂ fluid, weakly enriched in Mo, produced in a magma chamber by decompression-activated unmixing from a dense Mo-bearing NaCl-H₂O-CO₂ fluid. ³⁴S values of most sulphides range from c. 0 at Murvey to 3–4 at Mace Head and are consistent with a magmatic origin. Most quartz vein samples have ¹⁸O of 9–10.3 and were precipitated from a hydrothermal fluid with ¹⁸O of 4.6–6.7. Some have ¹⁸O of 6–7 and reflect introduction of meteoric water along vein margins. Quartz-muscovite oxygen isotope geothermometry combined with fluid inclusion data indicate precipitation of mineralized veins in the temperature range 360–450°C and between 1 and 2 kb. Whole rock granite samples display a clear ¹⁸O-D trend towards the composition of Connemara meteoric waters. The mineralization is interpreted as having been produced by highlyfractionated granite magma; meteoric water interaction postdates the main mineralizing event. The differences between the Mace Head and Murvey mineralizations reflect trapping of migrating mineralizing fluid in structural traps at Mace Head and precipitation of mineralization in the granite itself at Murvey.     

Significance of orthopyroxene and major element constraints on the petrogenesis of Ferrar tholeiites from southern Prince Albert Mountains, Victoria Land, Antarctica

The least evolved Jurassic Ferrar tholeiites from southern Prince Albert Mountains (Antarctica) are characterized by the occurrence of orthopyroxene (opx), a mineralogical feature virtually absent in the tholeiites from the large igneous provinces of Karoo (South Africa) and Paraná (Brazil). Petrography suggests that opx is the early phase in the sequence of crystallization and mineral chemistry indicates that it is in equilibrium with the host rock. In general, MELTS modeling predicts that opx is the liquidus phase in the Ferrar tholeiites with MgO higher than ~7 wt% at P=1.5-5 kbar, H₂O=0-1 wt% and % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavTnhis1MBaeXatLxBI9gBae % bbnrfifHhDYfgasaacH8YjY-vipgYlH8Gipec8Eeeu0xXdbba9frFj % 0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9 % vr0-vr0-vqpWqaaeaabiGaaiaacaqabeaabaqaamaaaOqaaiabdAga % MTWaaSbaaeaacqqGpbWtaeqaaWWaaSbaaeaadaWgaaqaaiabikdaYa % qabaaabeaakiabg2da9iabbgfarjabbAeagjabb2eanjabgkHiTiab % igdaXiaaysW7cyGGSbaBcqGGVbWBcqGGNbWzaaa!381A! = QFM - 1 f_{\rm O} _{_2 } = {\rm QFM} - 1\;\log unit conditions. MELTS results also show that the early crystallization of opx is primarily controlled by high SiO₂ and high SiO₂/CaO, chemical characteristics typical of the Ferrar tholeiites, but not shown by the Karoo and Paraná analogs with similar MgO content. Major element geochemistry of the least evolved Ferrar tholeiite has been modeled through fractional crystallization and fractional crystallization coupled with crustal assimilation processes, starting from natural peridotite-derived experimental melts. Mass balance and MELTS modeling support the argument that theoretical magma compositions suitable to be primary to the least evolved Ferrar tholeiites are compatible with hydrous (H₂O=0.3-0.5 wt%) and anhydrous melts obtained at 10-15 kbar by high melting degrees (>25%) of fertile and depleted spinel lherzolites, respectively, and later contaminated by the high-grade metamorphic rocks from the Victoria Land crystalline basement. The genesis of primary Ferrar tholeiites does not necessarily reflect the generally assumed depleted source mantle being also compatible with a fertile one.     

Validation of the stochastic distorted-wave Born approximation model with broad bandwidth total target strength measurements of Antarctic krill

In the computations of SDWBA_TTS(f) in Figure 4, the scatteredvector was integrated over all orientations in the XY plane,where X is the main axis of the krill, but a factor of 2 was     

Observed and modelled tidal currents in the New Zealand region

Tidal currents derived from current meter measurements are compared with the output from a barotropic tidal model of the New Zealand region. For the semi‐diurnal constituents there was very good agreement for the M₂ tide and good agreement for the S₂ tide. For the diurnal constituents (K_l, O_l) it was found that as the amplitude of the constituents decreased so did both the model/observation agreement and the accuracy of the observed tidal ellipse parameters. Consequently it was not possible to decide whether differences arose through shortcomings in the model or in the data. However, the overall performance of the model as a prognostic tool for ocean tidal current simulation appears to be good.     

The Regional Ocean Modeling System (ROMS) 4-dimensional variational data assimilation systems: Part II - Performance and application to the California Current System

The Regional Ocean Modeling System (ROMS) 4-dimensional variational (4D-Var) data assimilation systems have been systematically applied to the mesoscale circulation environment of the California Current to demonstrate the performance and practical utility of the various components of ROMS 4D-Var. In particular, we present a comparison of three approaches to 4D-Var, namely: the primal formulation of the incremental strong constraint approach; the dual formulation “physical-space statistical analysis system”; and the dual formulation indirect representer approach. In agreement with theoretical considerations all three approaches converge to the same ocean circulation estimate when using the same observations and prior information. However, the rate of convergence of the dual formulation was found to be inferior to that of the primal formulation. Other aspects of the 4D-Var performance that relate to the use of multiple outer-loops, preconditioning, and the weak constraint are also explored. A systematic evaluation of the impact of the various components of the 4D-Var control vector (i.e. the initial conditions, surface forcing and open boundary conditions) is also presented. It is shown that correcting for uncertainties in the model initial conditions exerts the largest influence on the ability of the model to fit the available observations. Various important diagnostics of 4D-Var are also examined, including estimates of the posterior error, the information content of the observation array, and innovation-based consistency checks on the prior error assumptions. Using these diagnostic tools, we find that more than 90% of the observations assimilated into the model provide redundant information. This is a symptom of the large percentage of satellite data that are used and to some extent the nature of the data processing employed. This is the second in a series of three papers describing the ROMS 4D-Var systems.