Photometric investigation and orbital period analyses of the W UMa binaries FP Lyn,FV CVn and V354 UMa     

Raul Michel  Qi-Qi Xia  Jesus Higuera 《天文和天体物理学研究(英文版)》2019,(7)

New light curves and photometric solutions of FP Lyn, FV CVn and V354 UMa are presented.We found that these three systems are W-subtype shallow contact binaries. In addition, it is obvious that the light curves of FP Lyn and V354 UMa are asymmetric. Therefore, a hot spot was added on the primary star of FP Lyn and a dark spot was added on the secondary star of V354 UMa. At the same time, we added a third light to the photometric solution of FP Lyn for the final result. The obtained mass ratios and fill-out factors are q = 1.153 and f = 13.4% for FP Lyn, q = 1.075 and f = 4.6% for FV CVn, and q = 3.623 and f = 10.7% for V354 UMa respectively. The investigations of orbital period for these three systems indicate that the periods are variable. FP Lyn and V354 UMa were discovered to have secularly increasing components with rates of dp/dt = 4.19 × 10~(-7) d yr~(-1) and dp/dt = 7.70 × 10~(-7) d yr~(-1) respectively,which are feasibly caused by conservative mass transfer from the less massive component to the more massive component. In addition, some variable components were discovered for FV CVn, including a rate of dp/dt =~(-1).13 × 10~(-6) d yr~(-1) accompanied by a cyclic oscillation with amplitude and period of 0.0069 d and 10.65 yr respectively. The most likely explanation for the long-term decrease is angular momentum loss.The existence of an additional star is the most plausible explanation for the periodic variation.  相似文献   

Air–sea carbon dioxide fluxes in the coastal southeastern tropical Pacific     

Gernot E. Friederich  Jesus Ledesma  Osvaldo Ulloa  Francisco P. Chavez 《Progress in Oceanography》2008,79(2-4):156

Comprehensive sea surface surveys of the partial pressure of carbon dioxide (pCO₂) have been made in the upwelling system of the coastal (0–200 km from shore) southeastern tropical Pacific since 2004. The shipboard data have been supplemented by mooring and drifter based observations. Air–sea flux estimates were made by combining satellite derived wind fields with the direct sea surface pCO₂ measurements. While there was considerable spatial heterogeneity, there was a significant flux of CO₂ from the ocean to the atmosphere during all survey periods in the region between 4° and 20° south latitude. During periods of strong upwelling the average flux out of the ocean exceeded 10 moles of CO₂ per square meter per year. During periods of weaker upwelling and high productivity the CO₂ evasion rate was near 2.5 mol/m²/yr. The average annual fluxes exceed 5 mol/m²/yr. These findings are in sharp contrast to results obtained in mid-latitude upwelling systems along the west coast of North America where the average air–sea CO₂ flux is low and can often be from the atmosphere into the ocean. In the Peruvian upwelling system there are several likely factors that contribute to sea surface pCO₂ levels that are well above those of the atmosphere in spite of elevated primary productivity: (1) the upwelling source waters contain little pre-formed nitrate and are affected by denitrification, (2) iron limitation of primary production enhanced by offshore upwelling driven by the curl of the wind stress and (3) rapid sea surface warming. The combined carbon, nutrient and oxygen dynamics of this region make it a candidate site for studies of global change.  相似文献   

Paleolimnologically inferred eutrophication of a shallow, tropical, urban reservoir in southeast Brazil     

Sandra Costa-B?ddeker  Helen Bennion  Tatiane Araújo de Jesus  Ana Luiza S. Albuquerque  Rubens C. L. Figueira  Denise de C. Bicudo 《Journal of Paleolimnology》2012,48(4):751-766

We studied the eutrophication history of a tropical shallow reservoir in the S?o Paulo metropolitan region, southeast Brazil. We analyzed grain size, geochemistry, diatom assemblages, and land-use records in a sediment core from the reservoir to infer its trophic state history during the last ~110?years (1894?C2005). Eighty diatom species were observed in the core and shifts in the relative abundances of planktonic and benthic taxa indicate major limnological changes associated with complex interactions between hydrologic factors and eutrophication. Discostella stelligera was associated with deforestation and water physical changes whereas Aulacoseira granulata, a species abundant throughout the core, was mostly associated with high flux conditions and erosion events, regardless of trophic state. Eutrophication was triggered by construction of the city zoo (1958) and installation of the S?o Paulo State Department of Agriculture (1975) within the Gar?as watershed, and increasing loads of untreated sewage from these institutions. The data suggest that deterioration in water quality began after ~1975 and markedly accelerated after ~1990. The reservoir has been hypereutrophic since 1999. Steady increases in geochemical proxies for trophic state, along with a decrease in C/N ratios, indicated higher nutrient concentrations and the prevalence of autochthonous production towards the core top. Appearance of Achnanthidium catenatum ~1993 highlighted the onset of a marked eutrophication phase. The subsequent dominance of Planothidium rostratum and Cyclotella meneghiniana suggested a sharp shift to a hypereutrophic state since 1999. Land-use history proved valuable for validating the chronology and interpreting anthropogenic impacts. Multi-proxy analysis of the sediment record provided an effective tool for tracking ecological shifts in the reservoir ecosystem. This study provides the first reconstruction of lake eutrophication history in Brazil and highlights the importance of hydrological/physical changes as drivers of diatom assemblage shifts in reservoirs, which may confound trophic state inferences based on shifts in the planktonic/benthic diatom ratio.  相似文献   

Contribution of groundwater to the outflow from ungauged glacierized catchments: a multi‐site study in the tropical Cordillera Blanca,Peru          下载免费PDF全文

Michel Baraer  Jeffrey McKenzie  Bryan G. Mark  Ryan Gordon  Jeffrey Bury  Thomas Condom  Jesus Gomez  Sara Knox  Sarah K. Fortner 《水文研究》2015,29(11):2561-2581

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Geology of southeast Bohol,central Philippines: Accretion and sedimentation in a marginal basin     

D. V. Faustino  G. P. Yumul  J. V. De Jesus  C. B. Dimalanta  J. C. Aitchison  M-F. Zhou 《Australian Journal of Earth Sciences》2013,60(4):571-583

Recent field mapping has refined our understanding of the stratigraphy and geology of southeastern Bohol, which is composed of a Cretaceous basement complex subdivided into three distinct formations. The basal unit, a metamorphic complex named the Alicia Schist, is overthrust by the Cansiwang mélange, which is, in turn, structurally overlain by the Southeast Bohol Ophiolite Complex. The entire basement complex is overlain unconformably by a ～2000 m thick sequence of Lower Miocene to Pleistocene carbonate and clastic sedimentary rocks and igneous units. Newly identified lithostratigraphic units in the area include the Cansiwang mélange, a tectonic mélange interpreted as an accretionary prism, and the Lumbog Volcaniclastic Member of the Lower Miocene Carmen Formation. The Cansiwang mélange is sandwiched between the ophiolite and the metamorphic complex, suggesting that the Alicia Schist was not formed in response to emplacement of the Southeast Bohol Ophiolite Complex. The accretionary prism beneath the ophiolite complex and the presence of boninites suggest that the Southeast Bohol Ophiolite Complex was emplaced in a forearc setting. The Southeast Bohol Ophiolite Complex formed during the Early Cretaceous in a suprasubduction zone environment related to a southeast‐facing arc (using present‐day geographical references). The accretion of this ophiolite complex was followed by a period of erosion and then later by extensive clastic and carbonate rock deposition (Carmen Formation, Sierra Bullones Limestone and Maribojoc Limestone). The Lumbog Volcaniclastic Member and Jagna Andesite document intermittent Tertiary volcanism in southeastern Bohol.  相似文献   

Identifying strengths and limitations of pan-European forest cover maps through spatial comparison     

Lucia Maria Seebach  Peter Strobl  Jesus San Miguel-Ayanz  Annemarie Bastrup-Birk 《International journal of geographical information science》2013,27(11):1865-1884

Detailed and harmonized information on spatial forest distribution is an essential input for forest-related environmental assessments, in particular, for biomass and growing stock modeling. In the last years, several mapping approaches have been developed in order to provide such information for Europe in a harmonized way. Each of these maps exhibits particular properties and varies in accuracy. Yet, they are often used in parallel for different modeling purposes. A detailed spatial comparison seemed necessary in order to provide information on the advantages and limitations of each of these forest cover maps in order to facilitate their selection for modeling purposes.

This article confronts the high-resolution forest cover map recently developed by the Joint Research Centre for the year 2000 (FMAP2000) with previously existing maps for the same time period: the CORINE Land Cover 2000 (CLC2000) and the Calibrated European Forest Map 1996 (CEFM1996). The spatial comparison of these three maps was carried out based on forest proportion maps of 1 km derived from the original maps. To characterize differences according to biogeographic regions, two criteria were used: detail of thematic content within each map and local spatial agreement.

Concerning thematic content, CLC2000 displayed a surfeit of non-forested areas at the cost of low forest proportions, while FMAP2000 showed a more balanced distribution likely to preserve more detail in forest spatial pattern. Good spatial agreement was found for CLC2000 and FMAP2000 within about 70% of the study area, while only 50% agreement was found when compared with CEFM1996. The largest spatial differences between all maps were found in the Alpine and Mediterranean regions. Reasons for these might be different input data and classification techniques and, in particular, the calibration of CEFM1996 to reported national statistics.  相似文献   

Mixing induced reactive transport in fractured crystalline rocks     

Lurdes Martinez-Landa  Jesus Carrera  Marco Dentz  Daniel Fernàndez-Garcia  Albert Nardí  Maarten W. Saaltink 《Applied Geochemistry》2012

In this paper the solute retention properties of crystalline fractured rocks due to mixing-induced geochemical reactions are studied. While fractured media exhibit paths of fast flow and transport and thus short residence times for conservative solutes, at the same time they promote mixing and dilution due to strong heterogeneity, which leads to sharp concentration contrasts. Enhanced mixing and dilution have a double effect that favors crystalline fractured media as a possible host medium for nuclear waste disposal. Firstly, peak radionuclide concentrations are attenuated and, secondly, mixing-induced precipitation reactions are enhanced significantly, which leads to radionuclide immobilization. An integrated framework is presented for the effective modeling of these flow, transport and reaction phenomena, and the interaction between them. In a simple case study, the enhanced dilution and precipitation potential of fractured crystalline rocks are systematically studied and quantified and contrasted it to retention and attenuation in an equivalent homogeneous formation.  相似文献   

Active Fire Detection for Fire Emergency Management: Potential and Limitations for the Operational Use of Remote Sensing     

Jesus?San-Miguel-AyanzEmail author  Nicolas?Ravail 《Natural Hazards》2005,35(3):361-376

The use of the mid-infrared and thermal bands of sensors on board airborne platforms and satellites permits the detection of active fires on the Earths surface. This application has been available to the fire-fighting community for many years. However, limitations in the fire detection capabilities of the sensors and/or the lack of adequate re-visit frequency have prevented the use of these systems for operational forest fire-fighting. In addition to mobile systems, remote sensors positioned on fixed fire-watch towers have also been used for active fire detection. These instruments are often positioned in strategic look-out places to provide continuous monitoring of the surrounding areas. They locate fires through the detection of either hot spots (areas of increased temperature in comparison to the background) or smoke plumes produced by the fires. This article evaluates the use of existing remote sensing systems for active fire detection, with emphasis on the applicability of these systems for fire emergency management and fire-fighting. Long-range remote sensing devices on board satellites are considered, airborne systems are assessed, and short-range fire detection instruments on fixed ground platforms are reviewed. A short introduction to forthcoming satellite systems, which will be based on the combined use of several small satellites, is presented. The advantages and drawbacks of the different systems are evaluated from a fire management perspective.  相似文献   

Climate change in the Iberian Upwelling System: a numerical study using GCM downscaling     

Ana Cordeiro Pires  Rita Nolasco  Alfredo Rocha  Alexandre M. Ramos  Jesus Dubert 《Climate Dynamics》2016,47(1-2):451-464

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Rare-earth elements in groundwaters from the Osamu Utsumi mine and Morro do Ferro analogue study sites, Poços de Caldas, Brazil     

N. Miekeley  H. Coutinho de Jesus  C.L. Porto da Silveira  P. Linsalata  R. Morse 《Journal of Geochemical Exploration》1992,45(1-3)

Data are presented on rare-earth elements (REE) in prefiltered (<450 nm) near-surface and deeper groundwaters and in corresponding particulate matter (>450 nm) from the Osamu Utsumi uranium mine and the Morro do Ferro thorium-REE-deposit. Groundwaters from both sites typically contain between 1–50 μg/l of total REE, but can reach values of up to 160 μg/l in the deepest borehole F4 (U-Mine: 150–415 m). Even higher REE concentrations of up to 29 mg/l were measured in acidic, sulfate-rich near-surface waters of the same site. The chondrite-normalized REE patterns in deeper, more reducing groundwaters and in their corresponding suspended particle fractions are similar to those observed in the bedrock (phonolites), indicating that bedrock leaching and secondary mineral sorption occurred without significant fractionation between these elements, in accordance with the only small variations in the stability constants of the expected REE-sulfate complexes in these waters. Groundwaters from the unsaturated zone of both sites show a very characteristic cerium depletion (less pronounced than that observed in the corresponding suspended particulate fractions), which is most probably related to the oxidation of Ce (III) under the prevailing E_h-conditions of these waters (600 to 800 mV), and to sorption/precipitation reactions of the much less soluble Ce(IV) species. Coarse particulate matter (>450 nm), composed mainly of amorphous ferric hydrous oxides, has a strong capacity for sorption of REE. This is shown by its very high REE concentrations, in some boreholes > 8,000 μg/g (total REE), and by the calculated association ratios R_a (ml/g), which are in the order of 10⁵ to 10⁶. The implications of these findings for the migration behavior of REE in both environments are discussed.  相似文献