Nocturnal Intermittent Coupling Between the Interior of a Pine Forest and the Air Above It     

Pablo E. S. Oliveira  Ot��vio C. Acevedo  Osvaldo L. L. Moraes  Hans R. Zimermann  Claudio Teichrieb 《Boundary-Layer Meteorology》2013,146(1):45-64

A 1-year set of measurements of CO₂ and energy turbulent fluxes above and within a 25-m pine forest in southern Brazil is analyzed. The study focuses on the coupling state between two levels and its impact on flux determination by the eddy-covariance method. The turbulent series are split in their typical temporal scales using the multiresolution decomposition, a method that allows proper identification of the time scales of the turbulent events. Initially, four case studies are presented: a continually turbulent, a continually calm, a calm then turbulent, and an intermittent night. During transitions from calm to turbulent, large scalar fluxes of opposing signs occur at both levels, suggesting the transference of air accumulated in the canopy during the stagnant period both upwards and downwards. Average fluxes are shown for the entire period as a function of turbulence intensity and a canopy Richardson number, used as an indicator of the canopy coupling state. Above the canopy, CO₂ and sensible heat fluxes decrease in magnitude both at the neutral and at the very stable limit, while below the canopy they increase monotonically with the canopy Richardson number. Latent heat fluxes decrease at both levels as the canopy air becomes more stable. The average temporal scales of the turbulent fluxes at both levels approach each other in neutral conditions, indicating that the levels are coupled in that case. Average CO₂ fluxes during turbulent periods that succeed very calm ones are appreciably larger than the overall average above the canopy and smaller than the average or negative within the canopy, indicating that the transfer of air accumulated during calm portions at later turbulent intervals affects the flux average. The implications of this process for mean flux determination are discussed.  相似文献   

Climate change in the Paraná state,Brazil: responses to increasing atmospheric CO 2 in reference evapotranspiration     

Lucas da Costa Santos  Jefferson Vieira Jos&#;  Fabiani Denise Bender  Daniel Soares Alves  Pablo Ricardo Nitsche  Elton Fialho dos Reis  Rubens Duarte Coelho 《Theoretical and Applied Climatology》2020,140(1):55-68

The hydrological variable evapotranspiration (ET) is challenging to estimate because it cannot be measured directly in natural environments (except in small plots). The uncertainties associated with the models used for its prediction have increased under climate change conditions. We studied the influence of stomatal resistance on ET estimates using the Penman-Monteith method as projected by three general circulation models in two emission scenarios (RCP4.5 and RCP8.5) for future climates throughout the twenty-first century (2010–2039, 2040–2069, and 2070–2099). We also investigated the probable ET rate changes in relation to the current (30 years average, 1980–2009) climate conditions for the Paraná state in the southern region of Brazil. The results were regionalized to help policymakers assess climate change impacts and design adaptation measures. ET increases of up to 15% were found in future climate conditions, which may lead to a significant increase in the water demand for agricultural crops. However, we believe that plant morphophysiological changes may occur under atmospheric CO2 enrichment conditions and that a possible reduction in stomatal conductance will result in lower ET increases than those obtained with the traditional Penman-Monteith method. When considering future climate scenarios, we propose the equation be adjusted to consider stomatal resistance as a function of CO2 concentrations.  相似文献   

Devonian F-rich peraluminous A-type magmatism in the proto-Andean foreland (Sierras Pampeanas,Argentina): geochemical constraints and petrogenesis from the western-central region of the Achala batholith     

Juan A. Dahlquist  Pablo H. Alasino  Carina Bello 《Mineralogy and Petrology》2014,108(3):391-417

A new LA-ICP-MS crystallization age of 370?±?8 Ma is presented for monzogranite from the Achala batholith, the largest Devonian igneous body in the Sierras Pampeanas, confirming previous U-Pb zircon ages and indicating emplacement within a relatively short episode. Granitic rocks from the central area of the batholith display restricted high SiO₂ contents (69.8–74.5 wt.%). Major element plots show ferroan and alkaline-calcic to calc-alkaline compositions with an A-type signature. High concentrations of the high field-strength elements such as Y, Nb, Ga, Ta, U, Th, and flat REE patterns with significant negative Eu anomalies, are also typical of A-type granites. The aluminium saturation index (1.10–1.37) indicates aluminous parent magmas which are further characterised by high FeO/MgO ratios (2.6–3.3) and F contents of igneous biotites (0.9–1.5 wt%), as well as relatively high Al^IV (2.39–2.58 a.p.f.u.) in biotites and the occurrence of primary muscovite. Petrogenetic modelling supports a source enriched in plagioclase and progressive fractional crystallization of feldspar. The central area of the batholith displays small-scale bodies composed predominantly of biotite (80 %), muscovite (10 %) and apatite (10 %), yielding rock compositions with 2.3–5.4 wt. % P₂O₅, and 6–7 wt.% F, together with anomalous contents of U (88–1,866 ppm), Zr (1081–2,581 ppm), Nb (257–1,395 ppm) and ΣREE (1,443–4,492 ppm). Previous studies rule out an origin of these bodies as metasedimentary xenoliths and they have been interpreted as cumulates from the granitic magma. An alternative flow segregation process is discussed here.  相似文献   

Biomarkers in croakers Micropogonias furnieri (Teleostei: Sciaenidae) from polluted and non-polluted areas from the Patos Lagoon estuary (Southern Brazil): evidences of genotoxic and immunological effects     

Amado LL  da Rosa CE  Leite AM  Moraes L  Pires WV  Pinho GL  Martins CM  Robaldo RB  Nery LE  Monserrat JM  Bianchini A  Martinez PE  Geracitano LA 《Marine pollution bulletin》2006,52(2):199-206

Biomarkers of exposure and effect of pollutants were analyzed in croakers Micropogonias furnieri (Teleostei: Sciaenidae) captured in winter and summer in a polluted and in a non-polluted site at the Patos Lagoon estuary (Southern Brazil). Catalase and glutathione S-transferase activities (exposure biomarkers) and lipid peroxidation (effect biomarker) were analyzed in liver samples. Other two effect biomarkers were also studied: blood cells DNA damage (through comet assay and micronucleus test) and respiratory burst measurements. In a broad view, results point to an important seasonal variation of the biochemical biomarkers analyzed. However, data obtained clearly indicate that croakers collected in winter at the polluted site were subjected to a level of clastogenic agents sufficient to generate irreversible genetic damages (mutations) and impair the fish immune system.  相似文献   

Mapping inundation probability due to increasing sea level rise along El Puerto de Santa María (SW Spain)     

Pablo Fraile-Jurado  José I. Álvarez-Francoso  Emilia Guisado-Pintado  Noela Sánchez-Carnero  José Ojeda-Zújar  Stephen P. Leatherman 《Natural Hazards》2017,87(2):581-598

Global sea levels have risen through the twentieth and twenty-first centuries. This rise will almost certainly continue and probably accelerate during the rest of the twenty-first century, albeit there is strong disagreement about the range of future sea level rise due to uncertainties regarding scenarios and emission of greenhouse gasses. Although the impacts of sea level rise are diverse, inundation during high tides is one of the most obvious and immediate consequences. A probabilistic methodology for mapping the inundation hazard because of sea level rise has been applied to the coast of El Puerto de Santa María in the province of Cádiz in southwest Spain. This methodology involves a step forward since represents the full range of probabilities, associated with each scenario of sea level rise considered, and thus offers a more realistic view of the probability of inundation in each area. Results show large differences in the spatial distribution of probable inundation in urban areas and wetlands leading to different consequences for management actions.  相似文献   

Behaviour of a new type of Runge–Kutta methods when integrating satellite orbits     

Ana B. González  Pablo Martín  David J. López 《Celestial Mechanics and Dynamical Astronomy》1999,75(1):29-38

Recently, González, Martín and Farto have developed new numerical methods (RKGM methods) of Runge–Kutta type and fixed step size for the numerical integration of perturbed oscillators. Moreover, it seems natural to study the behaviour of these new methods for the accurate integration of orbital problems after the application of linearizing transformation, such us KS or BF due to the fact that in these variables, the structure of the problem is of the form of perturbed oscillators, for which the methods constructed are indicated. In this paper, we check the efficiency of these new methods when integrating the satellite problem. The RKGM methods show a very good behaviour when they compete with other, classical and special, methods. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Reaction of a polar gravel-spit system to atmospheric warming and glacier retreat as reflected by morphology and internal sediment geometries (South Shetland Islands,Antarctica)     

Pablo Heredia Barión  Sebastian Lindhorst  Ilona Schutter  Ulrike Falk  Gerhard Kuhn 《地球表面变化过程与地形》2019,44(5):1148-1162

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