Forcing mechanisms of a heavy precipitation event in the southeastern Adriatic area     

Branka Ivančan-Picek  Kristian Horvath  Nataša Strelec Mahović  Marjana Gajić-Čapka 《Natural Hazards》2014,72(2):1231-1252

The aim of this study was to identify the main mesoscale features and mechanisms responsible for the generation of an extreme precipitation event as a contribution to improving the modelling of processes that produce HPEs. The event occurred during the morning hours on 22 November 2010 over the Dubrovnik coast in Croatia and the hinterland mountain range of the southern Dinaric Alps and caused severe flash floods and landslides and consequent interruption of traffic and electricity supply as well as other infrastructural damage. The analysis is geographically focused on the southern portion of the eastern Adriatic region, which is prone to relatively frequent heavy precipitation events that occur mostly in autumn. This area is one of the rainiest in Europe with expected annual amounts of precipitation greater than 5,000 mm in the mountainous hinterland. The mechanisms responsible for the formation of convection were analysed using synop measurements, satellite data and numerical experiments performed with the WRF model, which was set up at the convection-permitting resolution in the innermost domain. Satellite data were used to identify the precipitation systems and to estimate the intensity of the precipitation during the period of interest. The development of the precipitation system was connected to a strong large-scale ascent over the southern Italy and southern Adriatic due to the advection of warm air and cyclonic vorticity advection, which increases with height. The numerical simulations highlighted the essential role of a southerly low-level jet stream in the transport of warm and moist air towards the affected area. The convergence of two branches of low-level marine air favoured convection triggered over the coast and sea. Furthermore, numerical sensitivity experiments suggested that the orography of the Dinaric Alps plays an essential role in the precipitation maximum over the mountainous hinterland, but also that the orography was not the crucial factor in the heavy precipitation near Dubrovnik. This study highlights the need for a dense network of observations, especially radar measurements, to validate the simulated mechanisms and improve numerical forecasts via data assimilation.  相似文献   

Preservation of diagenetic products of β-carotene in sedimentary rocks from the Lopare Basin (Bosnia and Herzegovina)     

Nenad Grba  Aleksandra Šajnović  Ksenija Stojanović  Vladimir Simić  Branimir Jovančićević  Goran Roglić  Vladisav Erić 《Chemie der Erde / Geochemistry》2014

Sedimentary rocks from the saline formation of the Lopare Basin were investigated. Sediments contain a moderate amount of immature to marginally mature algal organic matter deposited under slightly reducing to anoxic and slightly saline to hypersaline conditions. Almost all of the samples contain β-carotane in a relatively high quantity, and in some, it represents the most abundant compound in the total distribution of hydrocarbons. The objective of the study was to determine the conditions that are favourable to precursors of β-carotene and/or the preservation of the carotenoid hydrocarbon skeleton. Moreover, the dominant transformation pathways of β-carotene under different redox and salinity conditions, which lead to the formation of aromatic carotenoids were defined.  相似文献   

The crystal structure of bøgvadite (Na2SrBa2Al4F20)     

Tonči Balić-Žunić 《Mineralogy and Petrology》2014,108(4):479-486

The crystal structure of bøgvadite, Na₂SrBa₂Al₄F₂₀, has been solved and refined to a R₁ factor of 4.4 % from single-crystal data (MoKα X-ray diffraction, CCD area detector) on a sample from the cryolite deposit at Ivittuut, SW Greenland. Bøgvadite is monoclinic, P2₁/n space group, with unit cell parameters a?=?7.134(1), b?=?19.996(3) and c?=?5.3440(8) Å, β?=?90.02(1)^o. A close proximity of the crystal structure to an orthorhombic symmetry and the presence of the two twin components in a nearly 1:1 ratio suggest that the investigated bøgvadite crystal has originally formed as a high-temperature orthorhombic polymorph which on cooling transformed to the stable low temperature monoclinic structure. The bøgvadite crystal structure has groupings of cation-fluoride coordination polyhedra similar to those found in the crystal structures of the genetically closely associated minerals jarlite and jørgensenite. However, its structure type is different from the latter two. The fluoridoaluminate framework of bøgvadite consists of infinite zig-zag chains of cis-connected AlF₆ coordination octahedra. The ¹ _∞[AlF₅] chains are interconnected by infinite chains of Na-F coordination polyhedra which extend in the same direction. Na is coordinated by nine F atoms if its full surrounding is taken in consideration, but makes significant chemical bonds only to closest five. The chains of AlF₆ and NaF₉ coordination polyhedra form double layers. In the centre of layers, relatively large voids in the form of pentagonal antiprisms are occupied by Sr atoms which make chemical bonds with the closest six F atoms. Between the SrF₁₀ coordinations in the centre of layers run empty channels. The double layers are interconnected by Ba atoms which are coordinated by eight F atoms and fill the spaces between the layers. Bøgvadite belongs to the group of fluoridoaluminates with infinite chains of cis-connected AlF₆ coordination octahedra, alike those found in the crystal structures of Ba-fluoridoaluminates.  相似文献   

Vulnerability to natural disasters in Serbia: spatial and temporal comparison     

Jelena Kovačević-Majkić  Milena Panić  Dragana Miljanović  Radmila Miletić 《Natural Hazards》2014,72(2):945-968

The frequency of natural disasters and the extent of their consequences at a global level are constantly increasing. This trend is partially caused by increased population vulnerability, which implies the degree of population vulnerability due to high-magnitude natural processes. This paper presents an analysis of vulnerability to natural disaster in Serbia in the second half of the twentieth and the early twenty-first century. Vulnerability changes were traced on the basis of demographic–economic indicators derived from statistical data for local government units (municipalities) provided by the Statistical Office of the Republic of Serbia. Calculations were performed in the geographical information system environment. The results of the study show that spatial and temporal vulnerability variations are causally correlated with changes in the selected components. Significant rise of vulnerability is related to urban areas, while lower values are characteristic for other areas of Serbia; this is primarily a consequence of different population density.  相似文献   

Photometric and spectrophotometric observations of Nova Delphini 1967     

A. Woszczyk  J. Smoliński  N. Maron  A. Strobel  J. Krempeć 《Astrophysics and Space Science》1968,1(2):264-272

Photographic, photovisual and photoelectric (V) observations of Nova Delphini 1967 were made from August 8 to October 31 (Table I, Figure 1). Simultaneously spectrophotometric measurements of the continuum were made on objective prism exposures extending to November 26, and spectrophotometric gradients derived (Tables II and III; Figures 3, 4, and 5). The continuum of Nova near its flat maximum is close to that of an early-type star in contrast to late-type absorptionline spectrum.  相似文献   

A note on the thermal component of the equation of state in solids     

Vladan čelebonović 《Earth, Moon, and Planets》1991,54(2):145-149

A simple method for determining the thermal component of the EOS of solids under high pressure is proposed. Application to the interior of the Earth gives results in agreement with recent geophysical data.  相似文献   

Automatic grid azimuth by hour angle of the sun,a star or a planet using an electronic theodolite Kern E2     

Nikola Solarić 《Astrophysics and Space Science》1991,177(1-2):175-179

The paper deals with the automatic grid azimuth determination of an object on the earth using the electronic theodolite Kern E2 by observing the sun, a star, or a planet. The observation time and the readings of horizontal and vertical circles of the electronic theodolite enter automatically the electronic calculator Hewlett-Packard HP41CX. The calculator computes the grid azimuth of the terrestrial object and directs the observer what to do. Therefore, even a personnel without specific high education can make observations. For the solar observations it is not necessary to have an astronomical almanac, because the program computes the solar coordinates. The general input data, together with the measured ones, can be stored on a magnetic cassette and later on, if necessary, one can correct the general data and recalculate the azimuth. The method proved to be very practical in the field work.  相似文献   

Historical torrential flood events in the Kolubara river basin   总被引：1，自引：0，他引：1  

Ana M. Petrović  Slavoljub S. Dragićević  Boris P. Radić  Ana Z. Milanović Pešić 《Natural Hazards》2015,79(1):537-547

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An example of karst catchment delineation for prioritizing the protection of an intact natural area     

Vesna Ristić Vakanjac  Zoran Stevanović  Aleksandra Maran Stevanović  Boris Vakanjac  Marina Čokorilo Ilić 《Environmental Earth Sciences》2015,74(12):7643-7653

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A model of neptune according to the Savić-Kašanin theory     

Vladan Čelebonović 《Earth, Moon, and Planets》1983,29(2):185-189

A model of the internal structure of Neptune has been calculated according to the Savi?-Ka?anin theory of behaviour of materials under high pressure.  相似文献