Greenhouse gas induced changes in the fire risk in Brazil in ECHAM5/MPI-OM coupled climate model     

Flavio Justino  A. S. de Mélo  A. Setzer  R. Sismanoglu  G. C. Sediyama  G. A. Ribeiro  J. P. Machado  A. Sterl 《Climatic change》2011,106(2):285-302

Vegetation fires are the second largest source of greenhouse gas emissions to the atmosphere. The reduction of the climatic impact of these emissions is related to the vegetation susceptibility to fire (fire risk), as well as to the understanding of possible implications of changes in atmospheric circulation on fire risk in the near-future. This study evaluates the environmental susceptibility to fire occurrence based on a Potential Fire Index (PFI). Two climate simulations from the ECHAM5/MPI-OM climate model have been used to calculate the PFI: present day (1980–2000) and an experiment for the end of the twenty-first century (2080–2100). The results indicate that the proposed PFI methodology could properly reproduce the areas with the highest fire incidence under present conditions. Moreover, it was found that under greenhouse warming conditions the PFI foresees an increase in the fire risk area, particularly for the Amazon region. We concluded, furthermore, that changes of vegetation predicted to occur in the future lead to substantial modifications in the magnitude of the PFI, and may potentially extend the length of the fire season due to induced longer drought periods as compared to current conditions.  相似文献   

Trends and variability of cloud fraction cover in the Arctic, 1982–2009     

Mauro?BoccolariEmail authorView author&#;s OrcID profile  Flavio?Parmiggiani 《Theoretical and Applied Climatology》2018,132(3-4):739-749

Climatology, trends and variability of cloud fraction cover (CFC) data over the Arctic (north of 70°N), were analysed over the 1982–2009 period. Data, available from the Climate Monitoring Satellite Application Facility (CM SAF), are derived from satellite measurements by AVHRR. Climatological means confirm permanent high CFC values over the Atlantic sector during all the year and during summer over the eastern Arctic Ocean. Lower values are found in the rest of the analysed area especially over Greenland and the Canadian Archipelago, nearly continuously during all the months. These results are confirmed by CFC trends and variability. Statistically significant trends were found during all the months over the Greenland Sea, particularly during the winter season (negative, less than ?5?%?dec ^?1) and over the Beaufort Sea in spring (positive, more than +5?%?dec ^?1). CFC variability, investigated by the Empirical Orthogonal Functions, shows a substantial “non-variability” in the Northern Atlantic Ocean. Statistically significant correlations between CFC principal components elements and both the Pacific Decadal Oscillation index and Pacific North America patterns are found.  相似文献   

Stability of biomass-derived black carbon in soils   总被引：16，自引：0，他引：16  

Biqing Liang  Dawit Solomon  Janice E. Thies  Flavio J. Luizão  Eduardo G. Neves 《Geochimica et cosmochimica acta》2008,72(24):6069-6078

Black carbon (BC) may play an important role in the global C budget, due to its potential to act as a significant sink of atmospheric CO₂. In order to fully evaluate the influence of BC on the global C cycle, an understanding of the stability of BC is required. The biochemical stability of BC was assessed in a chronosequence of high-BC-containing Anthrosols from the central Amazon, Brazil, using a range of spectroscopic and biological methods. Results revealed that the Anthrosols had 61-80% lower (P < 0.05) CO₂ evolution per unit C over 532 days compared to their respective adjacent soils with low BC contents. No significant (P > 0.05) difference in CO₂ respiration per unit C was observed between Anthrosols with contrasting ages of BC (600-8700 years BP) and soil textures (0.3-36% clay). Similarly, the molecular composition of the core regions of micrometer-sized BC particles quantified by synchrotron-based Near-Edge X-ray Fine Structure (NEXAFS) spectroscopy coupled to Scanning Transmission X-ray Microscopy (STXM) remained similar regardless of their ages and closely resembled the spectral characteristics of fresh BC. BC decomposed extremely slowly to an extent that it was not possible to detect chemical changes between youngest and oldest samples, as also confirmed by X-ray Photoelectron Spectroscopy (XPS). Deconvolution of NEXAFS spectra revealed greater oxidation on the surfaces of BC particles with little penetration into the core of the particles. The similar C mineralization between different BC-rich soils regardless of soil texture underpins the importance of chemical recalcitrance for the stability of BC, in contrast to adjacent soils which showed the highest mineralization in the sandiest soil. However, the BC-rich Anthrosols had higher proportions (72-90%) of C in the more stable organo-mineral fraction than BC-poor adjacent soils (2-70%), suggesting some degree of physical stabilization.  相似文献   

Climate change in lowland Central America during the late deglacial and early Holocene     

Michael B. Hillesheim  David A. Hodell  Barbara W. Leyden  Mark Brenner  Jason H. Curtis  Flavio S. Anselmetti  Daniel Ariztegui  David G. Buck  Thomas P. Guilderson  Michael F. Rosenmeier  Douglas W. Schnurrenberger 《第四纪科学杂志》2005,20(4):363-376

The transition from arid glacial to moist early Holocene conditions represented a profound change in northern lowland Neotropical climate. Here we report a detailed record of changes in moisture availability during the latter part of this transition (～11 250 to 7500 cal. yr BP) inferred from sediment cores retrieved in Lake Petén Itzá, northern Guatemala. Pollen assemblages demonstrate that a mesic forest had been largely established by ～11 250 cal. yr BP, but sediment properties indicate that lake level was more than 35 m below modern stage. From 11 250 to 10 350 cal. yr BP, during the Preboreal period, lithologic changes in sediments from deep‐water cores (>50 m below modern water level) indicate several wet–dry cycles that suggest distinct changes in effective moisture. Four dry events (designated PBE1‐4) occurred centred at 11 200, 10 900, 10 700 and 10 400 cal. yr BP and correlate with similar variability observed in the Cariaco Basin titanium record and glacial meltwater pulses into the Gulf of Mexico. After 10 350 cal. yr BP, multiple sediment proxies suggest a shift to a more persistently moist early Holocene climate. Comparison of results from Lake Petén Itzá with other records from the circum‐Caribbean demonstrates a coherent climate response during the entire span of our record. Furthermore, lowland Neotropical climate during the late deglacial and early Holocene period appears to be tightly linked to climate change in the high‐latitude North Atlantic. We speculate that the observed changes in lowland Neotropical precipitation were related to the intensity of the annual cycle and associated displacements in the mean latitudinal position of the Intertropical Convergence Zone and Azores–Bermuda high‐pressure system. This mechanism operated on millennial‐to‐submillennial timescales and may have responded to changes in solar radiation, glacial meltwater, North Atlantic sea ice, and the Atlantic meridional overturning circulation (MOC). Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Mapping the earthquake-induced landslide hazard around the main oil pipeline network of the Agri Valley (Basilicata,southern Italy) by means of two GIS-based modelling approaches     

Flavio Borfecchia  Gerardo De Canio  Luigi De Cecco  Alessandro Giocoli  Sergio Grauso  Luigi La Porta  Sandro Martini  Maurizio Pollino  Ivan Roselli  Alessandro Zini 《Natural Hazards》2016,80(2):759-773

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Detection of HCO⁺ towards Cygnus OB2 No. 12     

Flavio Scappini  Cesare Cecchi-Pestellini  Claudio Codella  Alexander Dalgarno 《Monthly notices of the Royal Astronomical Society》2000,317(1):L6-L10

HCO⁺ has been detected for the first time towards the star Cygnus OB2 No. 12 through emission of the 1–0 rotational transition at 89 GHz. The CO( J =2−1) transition has also been observed. The observations are consistent with a model of dense regions embedded in a low-density clump gas. If actually present, the dense component would have an aggregate size L 1300 au, in agreement with estimates of small-scale density fluctuations observed along diffuse lines of sight.  相似文献   

Chemical characteristics of groundwater around two massive sulphide deposits in an area of previous mining contamination, Iberian Pyrite Belt, Spain   总被引：1，自引：0，他引：1  

Hlne Pauwels  Marie-Lou Tercier-Waeber  Miguel Arenas  Ricardo Castroviejo  Yves Deschamps  Arnault Lassin  Flavio Graziottin  Francisco-Javier Elorza 《Journal of Geochemical Exploration》2002,75(1-3)

A detailed chemical study of groundwater was carried out to elucidate the processes controlling the oxidation and dissolution of sulphide minerals at two massive sulphide deposits in the Iberian Pyrite Belt (IPB), i.e. the mined La Zarza deposit and the unmined Masa Valverde deposit. It was found that major-element compositions varied according to the hydrological regime, La Zarza being in a relatively high area with groundwater recharge (and disturbance due to the human factor) and Masa Valverde being in a relatively low area with groundwater discharge. The variations mainly concern pH, Eh, SO₄ and Na concentrations. Metal concentrations were determined (a) by ICP-MS after filtration, and (b) in some cases by voltammetric measurement of Cu, Pb, Zn, Cd and Mn using the Voltammetric In situ Profiling (VIP) System, which allows detection of only the mobile fractions of trace elements (i.e., free metal ions and small labile complexes a few nanometers in size). If one compares the results obtained by each of the two methods, it would appear that the groundwater shows significant enhancement of metal solubility through complexing with organic matter and/or adsorption onto colloids and/or small particles. In areas of sulphide oxidation, however, this solubility enhancement decreases according to Cu>Zn>Cd>Pb. Under very low redox conditions, the attained metal concentrations can be several orders of magnitude (up to 10⁸–10⁹ for Cu and 10²–10³ for Pb) larger than those expected from equilibrium with respect to sulphide minerals as calculated with the EQ3NR geochemical code; Zn concentrations, however, are close to equilibrium with respect to sphalerite. The implication of these results is discussed with respect both to mineral exploration and to environmental issues.  相似文献   

CCD photometry of the Galactic globular cluster M13     

Barbara Paltrinieri  Francesco R. Ferraro  Flavio Fusi Pecci  & Eugenio Carretta 《Monthly notices of the Royal Astronomical Society》1998,293(4):434-442

In this paper, we present a B − V CCD colour–magnitude diagram (CMD) of the globular cluster M13 (NGC 6205), reaching down about 2 mag below the main sequence turn-off, based on a new, independent photometric calibration.
The most notable features of the CMD, including about 5500 stars, are (i) the long extension of the blue tail of the horizontal branch (HB), which can be traced down to V ∼19 and (moreover) shows the presence of two gaps; and (ii) the so-called bump on the red giant branch which is well-detected at V =14.75±0.05, using both the differential and integral luminosity functions.
No similar features have ever been detected in any previous ground-based photometry of this cluster.
A direct comparison between the CMD of M13 and M3, calibrated during the same run with the same apparatus, sets an upper limit of about 1.5 Gyr on their age difference, too small to explain the striking differences between their HB morphologies.  相似文献   

Lake sediments deposited on the Flims rockslide mass: the key to date the largest mass movement of the Alps     

Gaudenz Deplazes  Flavio S. Anselmetti  Irka Hajdas 《地学学报》2007,19(4):252-258

Long piston cores taken from the subsurface of two mountain lakes of the eastern Swiss Alps recovered sediments, which overlie the Flims rockslide deposits. These sediments provide new information on the chronology of the largest known Alpine rockslide and can be used to reconstruct the post landslide environmental evolution. The oldest ¹⁴C date of the lake sediments yields a minimum age of the rockslide at 9660–9430 cal. yr BP. In addition, the dating of a wood fragment contained in the rockslide deposits directly below the lake sediments shows a maximum age of 9480–9120 cal. yr BP. The overlap of the maximum and minimum ages, 9480–9430 cal. yr BP, approximates the age of the Flims rockslide. This early Holocene range coincides with a period of higher frequency of large mass movements observed in the Alps, which could be related to climatic changes.  相似文献   

Local geodetic and seismic energy balance for shallow earthquake prediction     

Flavio Cannavó  Alessandra Arena  Carmelo Monaco 《Journal of Seismology》2015,19(1):1-8

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