Estimation of daytime downward longwave radiation under clear and cloudy skies conditions over a sub-humid region

Downward longwave radiation (LW _↓ ) is a relevant variable for meteorological and climatic studies. Good estimates of this term are vitally important in correct determining of the net radiation, which, in turn, modulates the magnitude of the terms in the surface energy budget (e.g., evaporation). In remote sensing applications, the determination of daytime LW_↓ is required for estimation of the net radiation using satellite data. LW_↓ is not directly measured in weather stations and then is estimated using models with surface air temperature and humidity as input. In this paper, we identify the best models to estimate daytime downward longwave radiation from meteorological data in the sub-humid Pampean region. Several well-known models to estimate LW_↓ under clear and cloudy skies were tested. We use downward radiation components and meteorological data registered at Tandil (Argentina) from 2006 to 2010 (840 days). In addition, we propose two multiple linear regression models (MLRM-1 and MLRM-2) to estimate LW_↓ at the surface for all sky conditions. The new equations show better performance than the others models tested with root mean square errors between 12 and 16 W m^?2, bias close to zero and best agreements with measured data (r ²?≥?0.85).     

The great sulfur depletion of Earth’s mantle is not a signature of mantle–core equilibration

The extreme depletion of the Earth’s mantle in sulfur is commonly seen as a signature of metal segregation from Earth’s mantle to Earth’s core. However, in addition to S, the mantle contains other elements as volatile as S that are hardly depleted relative to the lithophile volatility trend although they are potentially as siderophile as sulfur. We report experiments in metal-sulfide–silicate systems to show that the CI normalized abundances of S, Pb, and Sn in Earth’s mantle cannot be reproduced by element partitioning in Fe ± S–silicate systems, neither at low nor at high pressure. Much of the volatile inventory of the Earth’s mantle must have been added late in the accretion history, when metal melt segregation to the core had become largely inactive. The great depletion in S is attributed to the selective segregation of a late sulfide matte from an oxidized and largely crystalline mantle. Apparently, the volatile abundances of Earth’s mantle are not in redox equilibrium with Earth’s core.     

An attenuation study using earthquakes from the 1997 Umbria-Marche sequence

We studied spatial and temporal characteristics of seismic attenuation inCentral Italy using S- and coda- waves recorded by the MarchesanSeismograph Network from earthquakes located in the epicentral area ofthe 1997 Umbria-Marche sequence. The amplitude decay of the S waveswith distance was defined calculating empirical attenuation functions at 15frequencies between 1 and 25 Hz. We analyzed separately foreshocks andaftershocks and we found the same attenuation functions, suggesting thatthe possible temporal variations could be confined in a small area. Thefrequency dependence of Q _S was approximated by the equation Q _S=18 · f ^2.0between 1 and 10 Hz. At higher frequencies (10–25 Hz), the frequencydependence of Q _s weakens, having an average value of Q _S=990. We also estimated Q from coda waves (Q _C) using the single-scattering models of Aki andChouet (1975) and Sato (1977). We found that Q _C=77 · f ^0.6, (between 2 and 20Hz) at the western side of the mountain chain, using either foreshocks oraftershocks. This relation is consistent with previous estimates of Q _Creported for the Central Apennines. For a volume sampling the Colfioritobasin, the Apennines and the Marche region we found that Q _C=55 · f ^0.8,indicating highattenuation below the mountain belt. To detect small temporal changes ofQ, we calculated spectral ratios of 5 temporal doublets located in theepicentral area and recorded at the closest station. We found temporalchanges of Q that vary from 27% to 56%, depending on the locationof the doublets. This variability suggests that the temporal change ofattenuation may depend on the spatial variation of Q and perhaps on thespatial distribution of tectonic stress in the epicentral area.     

Late Cretaceous eclogite in the Eastern Rhodopes (Bulgaria): evidence for subduction under the Sredna Gora magmatic arc

International Journal of Earth Sciences - The Rhodopes in Bulgaria and Greece represent a nappe stack of high-grade units with polymetamorphic history. Constraining the time of metamorphism in...     

The Early Palaeozoic high-grade metamorphism at the active continental margin of West Gondwana in the Andes (NW Argentina/N Chile)

The evolution of the Early Palaeozoic orogen of West Gondwana in the Cambrian to Ordovician basement of the Andes between ~18° and 32° S is investigated for pressure and temperature conditions and age of metamorphism. It is characterized by mid-crust temperatures commonly above the wet granite solidus (~650°C). Widespread felsic migmatite and rare granulite formed at pressures of ca 0.5?C0.7?GPa, locally 1.0?GPa. These rocks represent the deepest exhumed sections of the Early Palaeozoic crust. High pressure?Clow temperature rocks are absent. The crystallization ages, compiled from the literature in combination with new data, for near peak metamorphic conditions of these high-grade metamorphic rocks in NW Argentina and N Chile are ~530?C500?Ma and ~470?C420?Ma. Both age groups are spatially overlapping. Radiogenic isotope signatures (Sr, Nd, Pb) are used to characterize the Early Palaeozoic basement. The Pb and Sr isotope compositions of the Early Palaeozoic basement indicate mixing arrays between pre-Palaeozoic unradiogenic and radiogenic crust. Crustal residence ages (Sm?CNd T_DM) indicate a prominent event of crust formation around ~2?Ga, which is known continent-wide. This material was recycled during Midproterozoic and Early Palaeozoic orogenies without prominent additions of new crust present in the isotope record, i.e. accretion of compositional exotic material is absent.     

A contribution to the implementation of ICZM in the Mediterranean developing countries

The purpose of this paper is to assess the level of implementation of Integrated Coastal Zone Management (ICZM) principles in the Mediterranean developing countries at the moment of signing the protocol on ICZM for the Mediterranean, in the framework of the UNEP Mediterranean Action Plan of the Barcelona Convention. This assessment is based on the results of two advanced seminars on ICZM promoted by the Azahar programme of the Spanish Agency for International Cooperation for the Development (Ministry of Foreign Affairs and International Cooperation). The contribution of the participants of the seminar, who are representatives of national agencies related with ICZM in different Mediterranean countries, have been collected through a questionnaire including: (i) a ranking of the main coastal sectors and the main coastal issues of each country; (ii) significant initiatives for the sustainable development of the Mediterranean coastal zones; and (iii) the evaluation of the ICZM progress. The state of the coast, the level of implementation of ICZM and the main problems faced to apply it, have been detected for each country. None of the consulted countries have a full implemented integrated coastal zone management, the major problems being: (i) the lack of financial commitment for the implementation of ICZM; (ii) the lack of an assessment and monitoring system; (iii) the lack of knowledge regarding the coastal system; (iv) the lack of qualified human resources; and (v) the lack of public participation and administrative integration strategies based on information. From these conclusions, some recommendations to improve ICZM are also provided. The work presented in this paper is the starting point to assess the evolution and the reference from which ICZM will be improved through the protocol on ICZM for the Mediterranean.     

Middle Ordovician subduction of continental crust in the Scandinavian Caledonides: an example from Tjeliken,Seve Nappe Complex,Sweden

The Seve Nappe Complex of the Scandinavian Caledonides is thought to be derived from the distal passive margin of Baltica which collided with Laurentia in the Scandian Phase of the Caledonian Orogeny at 430–400 Ma. Parts of the Seve Nappe Complex were affected by pre-Scandian high- and ultrahigh-pressure metamorphism, in a tectonic framework that is still unclear, partly due to uncertainties about the exact timing. Previous age determinations yielded between ~ 505 and ~ 446 Ma, with a general trend of older ages in the North (Norrbotten) than in the South (Jämtland). New age determinations were performed on eclogite and garnet–phengite gneiss at Tjeliken in northern Jämtland. Thermodynamic modelling yielded peak metamorphic conditions of 25–27 kbar/680–760 °C for the garnet–phengite gneiss, similar to published peak metamorphic conditions of the eclogite (25–26 kbar/650–700 °C). Metamorphic rims of zircons from the garnet–phengite gneiss were dated using secondary ion mass spectrometry and yielded a concordia age of 458.9 ± 2.5 Ma. Lu–Hf garnet-whole rock dating yielded 458 ± 1.0 Ma for the eclogite. Garnet in the eclogite shows prograde major-element zoning and concentration of Lu in the cores, indicating that this age is related to garnet growth during pressure increase, i.e. subduction. The identical ages from both rock types, coinciding with published Sm–Nd ages from the eclogite, confirm subduction of the Seve Nappe Complex in Northern Jämtland during the Middle Ordovician in a fast subduction–exhumation cycle.     

Permanence of economic potential of cities based on sector development

The paper attempts to answer the following key question: how will a city′s world rank change in the face of crisis in its main economic sector? Crisis is defined here as a decline in financial performance in the given sector, which leads to the decline of its constituent firms and corporations on the world economic scene. The World Economic Center Index(WECI) has been created in order to rank cities based on the value of their resident corporations by sector and show their level of stability upon the removal of the most important sector. This provides information on the potential of each analyzed city as well as on its advanced features or area of specialization. Research has shown that nearly half the World Economic Centers are dominated by the financial and materials sectors of the economy. Different sectors dominate different regions of the world. For example, consumer staples and materials were dominant in North America, while information technology and financials were dominant in Europe. In Asia, several sectors tend to dominate the economy. Research has shown that the ability of a principal economic sector to resist economic crisis largely depends on the strength of the command and control function of a city. Finally, a high globalization level of a city is a key determinant of its susceptibility to economic crisis.