A Mediterranean derecho: Catalonia (Spain), 17th August 2003     

J. Manuel Lpez 《Atmospheric Research》2007,83(2-4):272-283

At approximately 6:10 UTC in the morning of 17th August 2003, a squall line developed over south Catalonia (the northeast region of Spain). During the next 9 h, the squall moved rapidly northeast and crossed Catalonia and the French regions of Languedoc–Roussillon and Province, damaging and uprooting hundreds of trees and blocking trains in the region. Wind gusts reached were recoded up to 52 m/s with evidence of F2 intensity damage. This case study shows the characteristics of a derecho (widespread convectively induced windstorm).Radar observations of the evolving squall line show signatures often correlated with damaging surface winds, including:

a. Bow echoes,

b. Rear inflow notches,

c. Rear inflow jets,

d. Medium altitude radial convergence,

e. Narrow gradient of very marked reflectivity,

f. Development of isolated cells ahead of the convective line,

g. A band of convection off the northern end of the line known as a “warm advection wing”.

When examining the different surface observations, satellite, radar imagery and cloud-to-ground lightning data, this case shows many similarities to those investigated in the United States. The derecho is a hybrid case, but has many characteristics of warm season derechoes. This emanates from a mesoscale convective complex (MCC) moving along a quasi-stationary, low-level thermal boundary in an environment characterized by high potential instability and relatively strong mid-tropospheric winds.  相似文献   

Aftershock tectonics of the 1978 Tabas-e-Golshan (Iran) earthquake sequence: a documented active 'thin-and thick-skinned tectonic' case     

Manuel Berberian 《Geophysical Journal International》1982,68(2):499-530

Summary. In this study a locally recorded aftershock sequence of the 1978 Tabas-e-Golshan earthquake ( M_s = 7.4) was accurately located. Out of 1560 located events, 329 best-located aftershocks passed a strict quality criterion. These well-located aftershocks, which have uncertainties in epicentre and in focal depth of about 1 and 2 km respectively, together with the well-constrained focal mechanisms, provided a detailed picture of active continental deformation during an aftershock sequence.
Almost all aftershocks follow very closely the pattern of the earthquake faults at the surface and lie in the hanging-wall block of the active fault. The hypocentres occurred mainly at depths less than 23 km with a high concentration of seismic activity between 8–14 km depth. The aftershocks clearly demonstrate an active imbricate listric thrust system with fault planes flattening into a basement decollement zone, and the reactivation of different basement reverse faults in response to a considerable amount of shortening of the top sedimentary cover. The sense of motion was almost universally thrusting and the aftershocks shared the same tectonic causes as the main shock.
The study indicates that the development of the young fold-thrust mountain belts necessarily involves basement shortening (thin-and thick-skinned tectonics) and that the 'frontal reverse faults' in young active fold-thrust mountain belts are the most seismically active faults. Geological and seismic data propose that the active frontal reverse fault systems are possibly reactivated old normal faults and may add support to the contention of reversal of fault motion during re thickening of continental crust. The active 'thin-and thick-skinned tectonics' documented in this study may prevail in other young and active fold-thrust mountain belts which are characterized by a thick sequence of telescoped top sedimentary cover over a decollement detachment zone.  相似文献   

NOBLE GAS ANOMALIES AND SYNTHESIS OF THE CHEMICAL ELEMENTS     

D.D. Sabu  O.K. Manuel 《Meteoritics & planetary science》1980,15(2):117-138

There are two types of planetary noble gases: One, containing isotopically “anomalous” argon, krypton and xenon but isotopically “normal” helium and neon, was derived from outer stellar regions. The other, consisting almost entirely of isotopically “normal” argon, krypton and xenon, with little or no helium or neon, was derived from inner stellar regions. Mixing of nucleosynthesis products from different regions of a supernova is responsible for the observed correlations between elemental and isotopic ratios of planetary noble gases in different classes of meteorites. The solar system condensed directly from the chemically and isotopically heterogeneous debris of a single supernova. There is no convincing evidence, however, of separate nucleogenetic components in neon. Fractionation and spallation can account for all previously identified components of trapped meteoritic neon, Ne-A, Ne-B, Ne-C, Ne-D, Ne-E, Ne-Al, Ne-A2, Ne-E(L), Ne-E(H) and Ne-O, and this same mechanism also explains differences between the isotopic compositions of meteoritic, atmospheric, and solar wind neon. Variations in the abundance pattern of planetary noble gases are primarily the result of stellar fusion reactions and physical adsorption, rather than gas solubility.  相似文献   

Paleolimnological investigations of anthropogenic environmental change in Lake Tanganyika: I. An introduction to the project     

Andrew S. Cohen  Manuel R. Palacios-Fest  James McGill  Peter W. Swarzenski  Dirk Verschuren  Robert Sinyinza  Tharcisse Songori  Bombi Kakagozo  Mutanga Syampila  Catherine M. O’Reilly  Simone R. Alin 《Journal of Paleolimnology》2005,34(1):1-18

We investigated paleolimnological records from a series of river deltas around the northeastern rim of Lake Tanganyika, East Africa (Tanzania and Burundi) in order to understand the history of anthropogenic activity in the lakes catchment over the last several centuries, and to determine the impact of these activities on the biodiversity of littoral and sublittoral lake communities. Sediment pollution caused by increased rates of soil erosion in deforested watersheds has caused significant changes in aquatic communities along much of the lakes shoreline. We analyzed the effects of sediment discharge on biodiversity around six deltas or delta complexes on the east coast of Lake Tanganyika: the Lubulungu River delta, Kabesi River delta, Nyasanga/Kahama River deltas, and Mwamgongo River delta in Tanzania; and the Nyamuseni River delta and Karonge/Kirasa River deltas in Burundi. Collectively, these deltas and their associated rivers were chosen to represent a spectrum of drainage-basin sizes and disturbance levels. By comparing deltas that are similar in watershed attributes (other than disturbance levels), our goal was to explore a series of historical experiments at the watershed scale, with which we could more clearly evaluate hypotheses of land use or other effects on nearshore ecosystems. Here we discuss these deltas, their geologic and physiographic characteristics, and the field procedures used for coring and sampling the deltas, and various indicators of anthropogenic impact.  相似文献   

Process‐based hydrological modelling: The potential of a bottom‐up approach for runoff predictions in ungauged catchments          下载免费PDF全文

Manuel Antonetti  Simon Scherrer  Peter Matthias Kienzler  Michael Margreth  Massimiliano Zappa 《水文研究》2017,31(16):2902-2920

Conceptual rainfall–runoff models are a valuable tool for predictions in ungauged catchments. However, most of them rely on calibration to determine parameter values. Improving the representation of runoff processes in models is an attractive alternative to calibration. Such an approach requires a straightforward, a priori parameter allocation procedure applicable on a wide range of spatial scales. However, such a procedure has not been developed yet. In this paper, we introduce a process‐based runoff generation module (RGM‐PRO) as a spin‐off of the traditional runoff generation module of the PREVAH hydrological modelling system. RGM‐PRO is able to exploit information from maps of runoff types, which are developed on the basis of field investigations and expert knowledge. It is grid based, and within each grid cell, the process heterogeneity is considered to avoid information loss due to grid resolution. The new module is event based, and initial conditions are assimilated and downscaled from continuous simulations of PREVAH, which are also available for real‐time applications. Four parameter allocation strategies were developed, on the basis of the results of sprinkling experiments on 60‐m² hillslope plots at several grassland locations in Switzerland, and were tested on five catchments on the Swiss Plateau and Prealps. For the same catchments, simulation results obtained with the best parameter allocation strategy were compared with those obtained with different configurations of the traditional runoff generation module of PREVAH, which was also applied as an event‐based module here. These configurations include a version that avoids calibration, one that transfers calibrated parameters, and one that uses regionalised parameter values. RGM‐PRO simulated heavy events in a more realistic way than the uncalibrated traditional runoff generation module of PREVAH, and, in some instances, it even exceeded the performance of the calibrated traditional one. The use of information on the spatial distribution of runoff types additionally proved to be valuable as a regionalisation technique and showed advantages over the other regionalisation approaches, also in terms of robustness and transferability.  相似文献   

Joint effects of climate warming and exotic litter (Eucalyptus globulus Labill.) on stream detritivore fitness and litter breakdown     

Francisco Correa-Araneda  Luz Boyero  Ricardo Figueroa  Carolina Sánchez  Roberto Abdala  Antonio Ruiz-García  Manuel A. S. Graça 《Aquatic Sciences - Research Across Boundaries》2015,77(2):197-205

  相似文献   

Physically based shallow translational landslide susceptibility analysis in Tibo catchment,NW of Portugal     

Manuel Teixeira  Carlos Bateira  Fernando Marques  Bianca Vieira 《Landslides》2015,12(3):455-468

  相似文献   

Terrain data compression using wavelet-tiled pyramids for online 3D terrain visualization     

Ricardo Olanda  Mariano Pérez  Juan Manuel Orduña  Silvia Rueda 《International journal of geographical information science》2014,28(2):407-425

Last years have witnessed the widespread use of online terrain visualization applications. However, the significant improvements achieved in sensing technologies have allowed an increasing size of the terrain databases. These increasing sizes represent a serious drawback when terrain data must be transmitted and rendered at interactive rates. In this paper, we propose a novel wavelet-tiled pyramid for compressing terrain data that replaces the traditional multiresolution pyramid usually used in wavelet compression schemes. The new wavelet-tiled pyramid modifies the wavelet analysis and synthesis processes, allowing an efficient transmission and reconstruction of terrain data in those applications based on multiresolution tiled pyramids. A comparative performance evaluation with the currently existing techniques shows that the proposed scheme obtains a better compression ratio of the terrain data, reducing the storage space and transmission bandwidth required, and achieving a better visual quality of the virtual terrain reconstructed after data decompression.  相似文献   

Identification of genes expressed in juvenile Haliotis rufescens in response to different copper concentrations in the north of Chile under controlled conditions     

Silva-Aciares F  Zapata M  Tournois J  Moraga D  Riquelme C 《Marine pollution bulletin》2011,62(12):2671-2680

This study reports molecular markers potentially associated with resistance or sensitivity to the impact of copper in juvenile red abalone, Haliotis rufescens, in the north of Chile under experimental conditions. Genomic analysis was made applying subtractive hybridization libraries (SSH) to identify genes up-and down regulated during cooper exposure in abalone over periods of 12 and 168 h exposed to 2.5 and 10 μg/L of Cu⁺². Results obtained from the SSH library revealed 368 different sequences regulated by copper, that correspond to eight major physiological functions. The validation of these sequences obtained by SSH as well as their expression kinetics were made by PCR in real time on 14 potential genes regulated by metal stress. This study provides information for the characterization of potential genomic markers that may be used in future environmental monitoring and to investigate new mechanisms of stress to copper in this commercially important marine species.  相似文献   

Variability of water mass properties in the last two decades in the South Adriatic Sea with emphasis on the period 2006-2009     

Vanessa Cardin  Manuel BensiMassimo Pacciaroni 《Continental Shelf Research》2011,31(9):951-965

Spatially averaged temperature and salinity profiles from individual cruises between 1990 and 2009 were analysed to outline the temporal evolution of water mass properties in the deep convection site in the South Adriatic Pit (SAP). The long-term variability in thermohaline conditions has been explained and related to a close feedback mechanism between the Ionian and the Adriatic Sea. Prominent influences of the Eastern Mediterranean Transient are manifested in changes in the vertical temperature and salinity patterns in the South Adriatic, and the whole studied period was divided into three stages according to the main thermohaline characteristics: 1990-1995, 1995-2004 and the last period from 2005 onwards.Particular attention was given to data collected during 2006-2009, which permitted us to situate the actual thermohaline properties in the context of the decadal variability. This last period was characterised by a very low production of dense water in the northern basin during 2007, while from winter 2008 high production of North Adriatic Deep Water (NAdDW) and Adriatic Deep Water (AdDW) in the northern and southern basins, respectively, was observed. Finally, we used the Optimum Multiparameter Analysis (OMP) to identify the percentages of the different water masses contained in the SAP, and this highlighted some differences between two recent periods studied (2007 and 2008) and the production of dense waters.  相似文献