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111.
dos Santos Janaína Cassiano Lyra Gustavo Bastos Abreu Marcel Carvalho de Oliveira-Júnior José Francisco Bohn Leonardo Cunha-Zeri Gisleine Zeri Marcelo 《Natural Hazards》2022,111(3):2531-2558
Natural Hazards - Desertification is a land degradation phenomenon with dire and irreversible consequences, affecting different regions of the world. Assessment of spatial climate susceptibility to... 相似文献
112.
Maurício Dambros Melati Fernando Mainardi Fan Gustavo Barbosa Athayde Pedro Antônio Roehe Reginato Walter Collischonn Camila de Vasconcelos Muller Athayde 《水文研究》2021,35(10):e14388
The anomalous entrance of water into groundwater systems can affect storage throughout long periods and normally relies on infrequent and irregular pulses of groundwater recharge defined by the term episodic recharge. Recently there was a groundwater recharge of large magnitude with unknown circumstances in the Caiuá aquifer. This unique event was explored in detail here and allowed to better understand the occurrence of such events in humid subtropical climates in South America. For this study, groundwater monitoring daily data from the Integrated Groundwater Monitoring Network was used combined with a specific yield obtained from geophysical wireline logging to obtain groundwater recharge rates. To improve the investigation, we also used a baseflow separation method to obtain the groundwater contribution into local rivers. The groundwater storage variations were also assessed by remote sensing with the GRACE data. Results showed the importance of high soil moisture storage on the occurrence of large episodic recharge events. We estimated that the groundwater recharger volumes derived from 1 year that included the unique episodic recharge observed (total of 866 mm for April 2015–March 2016) were comparable with the sum of 7 years of groundwater recharge (total of 867 mm). Atypical rainfall in winter periods were responsible for the increase in soil moisture that explained that unique event. GRACE-based GWS showed concordance detecting the occurrence of the unique episodic recharge. However, the variation in terms of volumes obtained by GRACE does not represent the behaviour observed in the aquifer by the WTF method. The results also indicated that changes in aquifer storage caused by episodic recharge events directly affect low flows in rivers over long periods. The main knowledge gap addressed here relates to exploring a unique episodic recharge event quite rare to observe with its long-term impacts on hydroclimatic variability over a humid subtropical portion of the Caiuá aquifer. 相似文献
113.
John J. Lyons Gregory P. Waite William I. Rose Gustavo Chigna 《Bulletin of Volcanology》2010,72(1):1-15
Fuego volcano, Guatemala is a high (3,800 m) composite volcano that erupts gas-rich, high-Al basalt, often explosively. It
spends many years in an essentially open vent condition, but this activity has not been extensively observed or recorded until
now. The volcano towers above a region with several tens of thousands of people, so that patterns in its activity might have
hazard mitigation applications. We conducted 2 years of continuous observations at Fuego (2005–2007) during which time the
activity consisted of minor explosions, persistent degassing, paroxysmal eruptions, and lava flows. Radiant heat output from
MODIS correlates well with observed changes in eruptive behavior, particularly during abrupt changes from passive lava effusion
to paroxysmal eruptions. A short-period seismometer and two low-frequency microphones installed during the final 6 months
of the study period recorded persistent volcanic tremor (1–3 Hz) and a variety of explosive eruptions. The remarkable correlation
between seismic tremor, thermal output, and daily observational data defines a pattern of repeating eruptive behavior: 1)
passive lava effusion and subordinate strombolian explosions, followed by 2) paroxysmal eruptions that produced sustained
eruptive columns, long, rapidly emplaced lava flows, and block and ash flows, and finally 3) periods of discrete degassing
explosions with no lava effusion. This study demonstrates the utility of low-cost observations and ground-based and satellite-based
remote sensing for identifying changes in volcanic activity in remote regions of underdeveloped countries. 相似文献
114.
115.
Gustavo E. Romero † Diego F. Torres I. Andruchow Luis A. Anchordoqui Bennett Link † 《Monthly notices of the Royal Astronomical Society》1999,308(3):799-806
Based on Link & Epstein's study of temporal asymmetry of 631 gamma-ray bursts from the BATSE 3B catalogue, we identify the population of bursts with rising times that are longer than their decays, thus showing atypical profiles. We analyse their sky distribution, morphology, time–space clustering and other average properties and compare them with those associated with the bulk of the bursts. We show how most of the peculiar bursts analysed are consistent with recent fireball models, but a fraction of bursts (∼4 per cent of the total sample) appear to be inconsistent. 相似文献
116.
Diego F. Torres Thomas M. Dame Gustavo E. Romero 《Astrophysics and Space Science》2005,297(1-4):393-398
In this paper we briefly comment on the observational status of the possible physical association between unidentified EGRET
sources and supernova remnants (SNRs) in our Galaxy. We draw upon recent results presented in the review by Torres et al.
(2003), concerning molecular gas in the vicinity of all 19 SNRs found to be positionally coincident with EGRET sources at
low Galactic latitudes. In addition, we present new results regarding the supernova remnant CTA 1. Our findings disfavor the
possibility of a physical connection with the nearby (in projection) EGRET source. There remains possible, however, that the
compact object produced in the supernova explosion be related with the observed γ-ray flux. 相似文献
117.
Jorge A. Combi Juan F. Albacete Colombo Gustavo E. Romero Paula Benaglia 《Astrophysics and Space Science》2007,309(1-4):395-399
We report hard X-ray emission of the non-thermal supernova remnant G337.2+0.1. The source presents centrally filled and diffuse
X-ray emission. A spectral study confirms that the column density of the central part of the object is about N
H∼5.9(±1.5)×1022 cm−2 and its X-ray spectrum is well represented by a single power-law with a photon index Γ=0.96±0.56. Detailed spectral analysis indicates that the outer region is highly absorbed and quite softer than the inner
region. Characteristics already observed in other well-known X-ray plerions. Based on the gathered information, we confirm
the SNR nature of G337.2+0.1, and suggest that the central region of the source is a pulsar wind nebula (PWN), originated
by an energetic though yet undetected pulsar. 相似文献
118.
A 2D depth‐averaged hydrodynamic, sediment transport and bed morphology model named STREMR HySeD is presented. The depth‐averaged sediment transport equations are derived from the 3D dilute, multiphase, flow equations and are incorporated into the hydrodynamic model STREMR. The hydrodynamic model includes a two‐equation turbulence model and a correction for the mean flow due to secondary flows. The suspended sediment load can be subdivided into different size classes using the continuum (two‐fluid) approach; however, only one bed sediment size is used herein. The validation of the model is presented by comparing the suspended sediment transport module against experimental measurements and analytical solutions for the case of equilibrium sediment‐laden in a transition from a rigid bed to a porous bed where re‐suspension of sediment is prevented. On the other hand, the bed‐load sediment transport and bed evolution numerical results are compared against bed equilibrium experimental results for the case of a meander bend. A sensitivity analysis based on the correction for secondary flow on the mean flow including the effect of secondary flow on bed shear stresses direction as well as the downward acceleration effect due to gravity on transverse bed slopes is performed and discussed. In general, acceptable agreement is found when comparing the numerical results obtained with STREMR HySeD against experimental measurements and analytical solutions. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
119.
Paula L. M. Gonzalez Lorenzo M. Polvani Richard Seager Gustavo J. P. Correa 《Climate Dynamics》2014,42(7-8):1775-1792
On a hemispheric scale, it is now well established that stratospheric ozone depletion has been the principal driver of externally forced atmospheric circulation changes south of the Equator in the last decades of the 20th Century. The impact of ozone depletion has been felt over the entire hemisphere, as reflected in the poleward drift of the midlatitude jet, the southward expansion of the summertime Hadley cell and accompanying precipitation trends deep into the subtropics. On a regional scale, however, surface impacts directly attributable to ozone depletion have yet to be identified. In this paper we focus on South Eastern South America (SESA), a region that has exhibited one of the largest wetting trends during the 20th Century. We study the impact of ozone depletion on SESA precipitation using output from 6 different climate models, spanning a wide range of complexity. In all cases we contrast pairs of model integrations with and without ozone depletion, but with all other forcings identically specified. This allows for unambiguous attribution of the computed precipitation trends. All 6 climate models consistently reveal that stratospheric ozone depletion results in a significant wetting of SESA over the period 1960–1999. Taken as a whole, these model results strongly suggest that the impact of ozone depletion on SESA precipitation has been as large as, and quite possibly larger than, the one caused by increasing greenhouse gases over the same period. 相似文献