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81.
Xiaolan L. Wang Hui Wan Francis W. Zwiers Val R. Swail Gilbert P. Compo Robert J. Allan Russell S. Vose Sylvie Jourdain Xungang Yin 《Climate Dynamics》2011,37(11-12):2355-2371
This study analyzes extremes of geostrophic wind speeds derived from sub-daily surface pressure observations at 13 sites in the European region from the Iberian peninsula to Scandinavia for the period from 1878 or later to 2007. It extends previous studies on storminess conditions in the Northeast (NE) Atlantic-European region. It also briefly discusses the relationship between storminess and the North Atlantic Oscillation (NAO). The results show that storminess conditions in the region from the Northeast Atlantic to western Europe have undergone substantial decadal or longer time scale fluctuations, with considerable seasonal and regional differences (especially between winter and summer, and between the British Isles-North Sea area and other parts of the region). In the North Sea and the Alps areas, there has been a notable increase in the occurrence frequency of strong geostrophic winds from the mid to the late twentieth century. The results also show that, in the cold season (December–March), the NAO-storminess relationship is significantly positive in the north-central part of this region, but negative in the south-southeastern part. 相似文献
82.
83.
Eddy resolving modelling of the Gulf of Lions and Catalan Sea 总被引:1,自引:1,他引:0
The generation process of strong long-lived eddies flowing southwestwards along the Catalan slope was revealed through numerical
modelling and in situ observations. Careful analyses of a particular event in autumn 2007 demonstrated a link between a “LATEX”
eddy, which remained in the southwestern corner of the Gulf of Lions and a “CATALAN” eddy, which moved along the Catalan Shelf,
since the death of the former gave birth to the latter. The origin of such eddies was found to be an accumulation of potential
energy in the southwestern corner of the Gulf of Lions: under the influence of the negative wind stress curl associated with
the Tramontane, a warm and less dense water body can be isolated and fed by a coastal current carrying warm water from the
Catalan Sea. In summer, this structure can grow and intensify to generate a strong anticyclonic eddy. After a long period
of Tramontane, a burst of southeasterlies and northerlies appeared to detach the “LATEX” eddy, which flowed out of the Gulf
of Lions, migrating along the Catalan continental slope and continued into the Balearic Sea as the “CATALAN” eddy. 相似文献
84.
Rémi Valois Christian Camerlynck Amine Dhemaied Roger Guerin Gaghik Hovhannissian Valérie Plagnes Faycal Rejiba Henri Robain 《地球表面变化过程与地形》2011,36(9):1183-1192
In the protection of karstic aquifers, the role played by dolines is of interest as these shallow structures can be preferential infiltration pathways for groundwater recharge. In this study, three depressions in South France (Orniac, Lot) were identified and characterized using combined geophysical methods. Apparent conductivity mapping allows precise definition of dolines corresponding to topographic depressions. It also reveals other dolines that are hidden by soil cover. Electrical resistivity and seismic refraction tomography provide detailed cross‐sections. Even though the dolines studied are close one to another, they exhibit great variability in shape and content. Moreover, time‐lapse data show that the most saturated regions are on the edges of the first doline. Such information helps to evaluate human impacts and forecast potential groundwater contamination. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
85.
I. D. Litovchenko A. V. Alakoz I. E. Val’tts G. M. Larionov 《Astronomy Reports》2011,55(12):1086-1095
Observations of various types of objects in the northern sky were obtained at 44 GHz in the 70-61
A
+ methanol line on the 20-m Onsala radio telescope (Sweden), in order to search for Class I methanol maser emission in the
interstellar medium: regions of formation of high-mass stars, dust rings around HII regions, and protostellar candidates associated
with powerful molecular outflows and Galactic HII regions. Seven new Class Imethanolmasers have been discovered toward regions
of formation of highmass stars, and the existence of two previously observed masers confirmed. The following conclusions are
drawn: (1) neither the association of a bipolar outflow manifest in the wings of CO lines with a highmass protostellar object
(HMPO) nor the presence of thermal emission in lines of complex molecules are sufficient conditions for the detection of Class
I methanol emission; no association with HMPOs radiating at 44 GHz was found for EGOs (a new class of object tracing bipolar
outflows); (2) the existence of H2O masers and Class II methanol masers in the region of aHMPOenhances the probability of detecting Class I methanol emission
toward the HMPO; Class II methanol masers with stronger line fluxes are associated with Class I methanol masers. 相似文献
86.
We present images of the star-forming regionG23.01–0.41 at 6.7GHz in the Class II methanol maser transition 51–60
A
+, produced from archival observations on the European VLBI Network. Our map of the source and its maser spots contains 24
maser components. The data for each spot—absolute coordinates, coordinates relative to the calibration feature, peak flux
and flux integrated over the spot, size, position angle, velocity along the line of sight, and line full width at half-maximum—are
collected in tabular form. The spatial region occupied by the maser spots is approximated by a 200×130 milliarcsec ellipse
in position angle PA = −0.40°, centered on the absolute coordinates α
0 = 18h34m40.282s, δ
0 = −09°00′38.27″ (J2000). If the source is a protoplanetary disk, then, for the distance estimate derived from trigonometric
parallax, its diameter is 1800 AU, and the mass of the central protostar is 23.5M
⊙. 相似文献
87.
Tidal dissipation is the main driver of orbital evolution of natural satellites and a key point to understand the exoplanetary system configurations. Despite its importance, its quantification from observations still remains difficult for most objects of our own Solar System. In this work, we overview the method that has been used to determine, directly from observations, the tidal parameters, with emphasis on the Love number \(k_2\) and the tidal quality factor Q. Up-to-date values of these tidal parameters are summarized. Last, an assessment on the possible determination of the tidal ratio \(k_2/Q\) of Uranus and Neptune is done. This may be particularly relevant for coming astrometric campaigns and future space missions focused on these systems. 相似文献
88.
Groundwater vulnerability is the likelihood of contaminants reaching the groundwater system after introduction at some location above the aquifer. The objective of this work was to investigate the relationship between total organic carbon concentration in groundwater and the intrinsic vulnerability of groundwater in karst areas at the regional scale. For this purpose hydrochemical data from 17 springs draining a Dinantian pure bedded Limestone rock unit were analysed to investigate their relationship with known parameters of groundwater vulnerability (e.g. degree of karstification, type of recharge). Statistical methods that could be useful to investigate such relationships are suggested. Principal components analysis showed the potential to visualise the relationships among hydrochemical data based on estimates of the median value. Multiple correspondence analysis was applied to visualise the relationship between total organic carbon and potential sources of organic carbon on the surface, a novel approach which has not been used in similar studies. Moreover, multiple regression analysis was used to determine the significance of these relationships. The results showed that, taking into consideration differences in background concentration, total organic carbon was significantly related to groundwater vulnerability. 相似文献
89.
Amaral Genilda Canuto Pezzopane José Eduardo Macedo de Souza Nóia Júnior Rogério Martínez Manuel Fernández Fonseca Mariana Duarte Silva Gibson Elbya Leão Toledo João Vitor Pezzopane José Ricardo Macedo Klippel Valéria Hollunder Xavier Talita Miranda Teixeira 《Theoretical and Applied Climatology》2022,147(1-2):347-361
Theoretical and Applied Climatology - The climate change endangers many species of the Amazon Forest. An example, in the endangered medicinal species Pilocarpus microphyllus (popularly known as... 相似文献
90.
Huu Hieu Ho Rudy Swennen Val��rie Cappuyns Elvira Vassilieva Tom Van Gerven Tan Van Tran 《Aquatic Geochemistry》2013,19(1):57-75
The speciation and mobility of some selected trace metals (As, Cu, Mn, Pb and Zn) in sediments with depth was investigated in the Cam River-mouth (Vietnam) by collecting sediment cores and analysing porewater and sediment composition, complemented with single (ammonium-EDTA) and sequential (BCR 3-step) extractions and mineralogical analysis (XRD). All trace metals show overall decreasing trends with depth in porewater as a result of anthropogenic input in upper sediment layers. High porewater concentrations of As, Mn and Pb in oxic and suboxic sediment layers may result in groundwater pollution. Sediment-bound Pb and Mn dominate in the reducible and the acid-soluble fraction, respectively, while Cu and Zn distribute rather evenly between four extracted fractions. The porewater metal speciation, as predicted by a geochemical model Visual MINTEQ version 3.0, indicates that the toxicity of Cu, Mn, Pb and Zn (presented by the proportions of free metal ions) decreases with depth, while the toxicity of As increases when As(III) becomes more abundant. The dissolved concentrations of trace metals are not only controlled by the precipitation/dissolution of discrete hydroxide/oxide, carbonate and phosphate minerals, but also by sorption processes on major sorbents (i.e. As on goethite, and Mn and Zn on calcite and dolomite). Sulphide minerals do not show any control even in the anoxic zone most likely because of the low concentration of sulphur. 相似文献