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   

Keeping the forest for the climate's sake: avoiding deforestation in developing countries under the UNFCCC     

Claudio Forneri  Jürgen Blaser  Frank Jotzo  Carmenza Robledo 《Climate Policy》2013,13(3):275-294

Abstract

A process for reducing emissions from deforestation in developing countries has been initiated under the UNFCCC. Efforts to agree on a legally binding instrument to halt deforestation have previously failed in other international fora. The magnitude of the social, economic, technical and political complexities underlying deforestation have led to negotiations being challenging. What policy instruments could provide incentives to reduce deforestation, and how could these instruments be framed, under the UNFCCC? This article analyses the advantages and disadvantages of the available alternatives within and outside of the Kyoto Protocol. Staying within the Kyoto framework means low institutional development costs, established but limited incentives for action, and low flexibility. Alternatives outside the Protocol provide higher institutional development costs, uncertainties with regard to the incentives, but greater flexibility. We argue that a separate protocol may be the most viable option, as it could offer the necessary flexibility and avoid some technical and political pitfalls that would be likely to beset new efforts under the Kyoto Protocol. The article also presents the concept of ‘committed forests’ as a means of defining geographically where the reduction of emissions from deforestation can take place.  相似文献   

Misattributed tsunami 3: the M_w 7.7 2013.9.24 SE Pakistan earthquake     

Claudio Vita-Finzi 《Proceedings of the Geologists' Association. Geologists' Association》2014

The M_w 7.7 earthquake that struck SE Pakistan on 24 September 2013 at 11.29.48 UTC was a sinistral strike-slip event on a branch of the Ornach-Nal-Chaman fault system which hereabouts separates the Eurasian Plate from the Indian Plate. Although the focus was at a depth of 15 km and 400 km inland the earthquake was accompanied by the emergence of an island off the Makran coast and the generation of a tsunami with a peak amplitude of 27 cm at Muscat (Oman) and 20 cm at Chah Bahar (Iran). At DART marine buoy 23228 in the Indian Ocean 500 km to the south a series of seismic Rayleigh waves about 4 min after the main shock was followed 54 min later by a tsunami with a peak amplitude of 1 cm. The Rayleigh series is here attributed to seafloor vibration during accelerated subduction of the Arabian Plate beneath the Eurasian Plate, and the tsunami to the development or reactivation of one or more reverse faults on the seaward portion of the Makran imbricate fan. As in the 2010.2.27 M_w 8.8 Maule (Chile), the 2004.12.26 M_w 9.2 Sumatra–Andaman, the 2005.3.28 M_w 8.7 Nias (Indonesia) and the 2011.3.11 M_w 9.0 Tohoku (Japan) earthquakes, the link between tsunami generation and slip on the megathrust is thus very indirect, to the detriment of attempts to mitigate coastal hazards using teleseismic data when nearshore seafloor monitoring would probably prove more effective.  相似文献   

Relationships between seep-carbonates,mud volcanism and basin geometry in the Late Miocene of the northern Apennines of Italy: the Montardone mélange     

Stefano Conti  Daniela Fontana  Claudio Corrado Lucente  Gian Andrea Pini 《International Journal of Earth Sciences》2014,103(1):281-295

The Montardone mélange (Mm) is a chaotic, block-in-matrix unit outcropping in the Montebaranzone syncline in the northern Apennines. The Mm occurs in the uppermost part of the Termina Fm, the Middle–Late Miocene interval of a succession deposited in a wedge-top slope basin (Epiligurian succession). The Mm is closely associated with bodies of authigenic carbonates, characterized by negative values of δ¹³C (from ?18.22 to ?39.05 ‰ PDB) and chemosynthetic benthic fauna (lucinid and vesicomyid bivalves). In this paper, we propose that the Mm is a mud volcano originated by the post-depositional reactivation and rising of a stratigraphically lower mud-rich mass transport body (Canossa–Val Tiepido sedimentary mélange or olistostrome) triggered by fluid overpressure. We base our conclusion on (1) the Mm pierces the entire Termina Fm and older Epiligurian units and represents the direct continuation of the underlying Canossa–Val Tiepido mélange; (2) the geometry and facies distribution of the Montebaranzone sandstone body, which are compatible with a confined basin controlled by the rising of the Mm; (3) the systematic presence of large-scale (lateral extension 300–400 m) seep-carbonates associated with the mélange, suggesting a persistent gas-enriched fluid vent from the ascending overpressured mud; (4) blocks and clasts sourced from the Mm, hosted by the authigenic carbonates, conveyed by ascending mud and gas-enriched fluids. The Mm represents one of the few fossil examples of reactivation of a basin-scale sedimentary mélange (olistostrome); a three-stage model showing mechanisms of Mm raising is proposed.  相似文献   

Estimating the hydraulic properties of an aquitard from in situ pore pressure measurements     

Brian D. Smerdon  Laura A. Smith  Glenn A. Harrington  W. Payton Gardner  Claudio Delle Piane  Joel Sarout 《Hydrogeology Journal》2014,22(8):1875-1887

A workflow is described to estimate specific storage (S _s) and hydraulic conductivity (K) from a profile of vibrating wire piezometers embedded into a regional aquitard in Australia. The loading efficiency, compressibility and S _s were estimated from pore pressure response to atmospheric pressure changes, and K was estimated from the earliest part of the measurement record following grouting. Results indicate that S _s and K were, respectively, 8.8?×?10^?6 to 1.2?×?10^?5 m^?1 and 2?×?10^?12 m s^?1 for a claystone/siltstone, and 4.3?×?10^?6 to 9.6?×?10^?6 m^?1 and 1?×?10^?12 to 5?×?10^?12 m s^?1 for a thick mudstone. K estimates from the pore pressure response are within one order of magnitude when compared to direct measurement in a laboratory and inverse modelled flux rates determined from natural tracer profiles. Further analysis of the evolution and longevity of the properties of borehole grout (e.g. thermal and chemical effects) may help refine the estimation of formation hydraulic properties using this workflow. However, the convergence of K values illustrates the benefit of multiple lines of evidence to support aquitard characterization. An additional benefit of in situ pore pressure measurement is the generation of long-term data to constrain groundwater flow models, which provides a link between laboratory scale data and the formation scale.  相似文献   

Petrophysical and mechanical properties of Euganean trachyte and implications for dimension stone decay and durability performance     

Luigi Germinario  Siegfried Siegesmund  Lara Maritan  Claudio Mazzoli 《Environmental Earth Sciences》2017,76(21):739

Euganean trachyte is a subvolcanic porphyritic rock extracted in northern Italy with an age-old tradition of use as dimension stone, historically linked, in particular, to the fervent building activity brought by the Roman Empire and, later on, the Republic of Venice Serenissima. The results of a comprehensive petrophysical and mechanical characterization of Euganean trachyte from the most representative quarries are discussed here, involving the following properties: density, porosity, water absorption, capillary water uptake, hygroscopic water adsorption, hydric/hygric dilatation, water vapor diffusion, thermal expansion, and resistance to salt attack and abrasion. The different trachyte varieties, although belonging to the same quarry basin, exhibit a relatively wide array of technical performances, which are strongly dependent on pore volume, size, size distribution, shape, and degree of interconnection, controlling modes and rates of water transport and retention. Therefore, indications are provided for evaluating durability performance of the stone, with stress on water-driven weathering. Complementary information is finally given on the possible criteria followed in the antiquity for properly selecting the trachyte quarries to be exploited, and by a comparison with the properties of the most important trachytes extracted in Europe.  相似文献